In video form:
Sunday, December 12, 2010
Alright, the long awaited update...
My apologies for not getting this out earlier, but here it is. First, let's take a look at the current radar trends:
As you can see, Lake Orion is just starting to get the prefrontal precipitation. It is falling as rain; however, forecast models support this changing over to snow by daybreak tomorrow morning. The next feature you will see is the massive hole of precipitation over Indiana & Illinois, and if you're like most people, you are probably freaking out thinking that you're going to miss out on a lot of the best snows. However, fear not. The low pressure system is forecast to move ESE over the next 12-18 hours, and as it does, the hole of precipitation, known scientifically as the "dry slot" of the storm, will also move ESE. Essentially, where it is right now is about as far north as I think it's going to get. I will say that if I have any viewers south of about I-696...you may have some trouble with the dry slot tomorrow, but I don't believe it will be for an extended period of time.
The main fun that's going to unfold for you guys tomorrow is from the band of heavy snow on the backside of the low pressure system that is currently falling in Wisconsin & Iowa. This is known as the "deformation band" or "trowal" in the meteorology world, and it is forecast to slide ESE into the Lake Orion area tomorrow. The further north you are, the more likely you are to catch the brunt of this band, so, for example, people in Saginaw are more likely to stay in this heavy snow axis for a longer period of time than people in Lake Orion, but people in Lake Orion will fare slightly better with this band of snow than people in, say, Canton (I think I have some readers in the Plymouth-Canton area ;).
So essentially, what I believe is going to happen is that in Lake Orion, precipitation will change over from rain to snow around daybreak as temperatures start to fall. In the early-mid morning hours, the snow may get a little lighter, and in areas to the south, the snow may stop falling completely for a few hours. However, around midday, I expect the snow to pick back up with a vengeance again, and to fall at a quick rate, until finally tapering off in the mid-late evening hours.
Snowfall Map:
At this time, I won't bother to post images of what all of the forecast models show, because they all show something similar. Essentially, all of the models show around .5-.8" of liquid equivalent falling in the Lake Orion area after the changeover to snow tomorrow. Using normal 10:1 snow-to-water ratios, this would equate to 5-8" of snow tomorrow. However, with the way that I believe temperatures will crash as this storm unfolds, I think the average ratios will be above 10:1, more like 12:1. This would equate to about 6-10" of snow for the Lake Orion area. However, the wettest model by far is the NAM, and it tends to overdo precipitation a little bit. As this is the only one that I feel would support 10" of snow falling, I'm going to try to trim accumulations to a range of 6-9". South of around I-696, I feel that the dry-slot will be a little more of an issue, and in addition to that, I feel that you make take a little longer to changeover from rain to snow. Due to this, I will cut accumulations down an inch there to 5-8". On the other hand, north of around I-69, I feel you'll have less trouble with the dryslot and a quicker changeover to snow, so I'll add an inch onto accumulations there, for a forecast of 7-10". The resulting map:
Impacts From This Storm:
I really don't have any other way to say it except to say that this storm will be an absolute nightmare for travel. Firstly, the rain you guys are currently getting will freeze under the snow on untreated roads such as dirt roads & subdivision streets. Obviously, the main roads will probably have more slush than anything on them because of salt & plows, but I still wouldn't advise anyone to travel anywhere unless absolutely necessary tomorrow, because the roads are going to be terrible. Secondly, the 6-9" of snow means it will be very difficult to get around after the storm is over on any unplowed roads. In addition, winds will gust to 30 mph near the end of the storm, and after the storm is over, causing very poor visibility as the freshly fallen snow is whipped up and blown all over the place. This will also cause drifts of over 1'. Finally, these winds combined with the temperature plunge will cause wind chills to drop well below zero on Sunday Night & Monday Morning.
Snow Day Chances:
In my opinion, if you guys want to throw any accomplishments my way on this storm (and really, you don't have to lol), it should be moreso for sniffing out the possibility of a storm in this timeframe over a week ago and then keeping you guys informed step-by-step as the storm became more and more likely to affect Lake Orion (of course, with many twists and turns in this case). I do not feel the actual snow day prediction will be very hard. Unless an absolute disaster happens w/ regards to accumulations, I feel you guys have a great shot at a snow day on Monday. Everything from the large amount of snow that will fall, to the sheet of ice on the back roads & subdivision roads due to the rain freezing over, to the poor visibility, to the extremely low wind chills all support a snow day. I will therefore give Monday a snow day grade of "A".
Once again, I'm very sorry I didn't get this up earlier. As always, feel free to leave questions/comments in the comment box below. The upside of this post getting posted later than expected is that I used the extra time to study more for my exams, meaning that I may put out an extra update tomorrow afternoon before my final snow day prediction which will be posted exactly at 7:30 p.m. Eastern Time (and that may be coming in video form if I feel that ambitious).
As you can see, Lake Orion is just starting to get the prefrontal precipitation. It is falling as rain; however, forecast models support this changing over to snow by daybreak tomorrow morning. The next feature you will see is the massive hole of precipitation over Indiana & Illinois, and if you're like most people, you are probably freaking out thinking that you're going to miss out on a lot of the best snows. However, fear not. The low pressure system is forecast to move ESE over the next 12-18 hours, and as it does, the hole of precipitation, known scientifically as the "dry slot" of the storm, will also move ESE. Essentially, where it is right now is about as far north as I think it's going to get. I will say that if I have any viewers south of about I-696...you may have some trouble with the dry slot tomorrow, but I don't believe it will be for an extended period of time.
The main fun that's going to unfold for you guys tomorrow is from the band of heavy snow on the backside of the low pressure system that is currently falling in Wisconsin & Iowa. This is known as the "deformation band" or "trowal" in the meteorology world, and it is forecast to slide ESE into the Lake Orion area tomorrow. The further north you are, the more likely you are to catch the brunt of this band, so, for example, people in Saginaw are more likely to stay in this heavy snow axis for a longer period of time than people in Lake Orion, but people in Lake Orion will fare slightly better with this band of snow than people in, say, Canton (I think I have some readers in the Plymouth-Canton area ;).
So essentially, what I believe is going to happen is that in Lake Orion, precipitation will change over from rain to snow around daybreak as temperatures start to fall. In the early-mid morning hours, the snow may get a little lighter, and in areas to the south, the snow may stop falling completely for a few hours. However, around midday, I expect the snow to pick back up with a vengeance again, and to fall at a quick rate, until finally tapering off in the mid-late evening hours.
Snowfall Map:
At this time, I won't bother to post images of what all of the forecast models show, because they all show something similar. Essentially, all of the models show around .5-.8" of liquid equivalent falling in the Lake Orion area after the changeover to snow tomorrow. Using normal 10:1 snow-to-water ratios, this would equate to 5-8" of snow tomorrow. However, with the way that I believe temperatures will crash as this storm unfolds, I think the average ratios will be above 10:1, more like 12:1. This would equate to about 6-10" of snow for the Lake Orion area. However, the wettest model by far is the NAM, and it tends to overdo precipitation a little bit. As this is the only one that I feel would support 10" of snow falling, I'm going to try to trim accumulations to a range of 6-9". South of around I-696, I feel that the dry-slot will be a little more of an issue, and in addition to that, I feel that you make take a little longer to changeover from rain to snow. Due to this, I will cut accumulations down an inch there to 5-8". On the other hand, north of around I-69, I feel you'll have less trouble with the dryslot and a quicker changeover to snow, so I'll add an inch onto accumulations there, for a forecast of 7-10". The resulting map:
Impacts From This Storm:
I really don't have any other way to say it except to say that this storm will be an absolute nightmare for travel. Firstly, the rain you guys are currently getting will freeze under the snow on untreated roads such as dirt roads & subdivision streets. Obviously, the main roads will probably have more slush than anything on them because of salt & plows, but I still wouldn't advise anyone to travel anywhere unless absolutely necessary tomorrow, because the roads are going to be terrible. Secondly, the 6-9" of snow means it will be very difficult to get around after the storm is over on any unplowed roads. In addition, winds will gust to 30 mph near the end of the storm, and after the storm is over, causing very poor visibility as the freshly fallen snow is whipped up and blown all over the place. This will also cause drifts of over 1'. Finally, these winds combined with the temperature plunge will cause wind chills to drop well below zero on Sunday Night & Monday Morning.
Snow Day Chances:
In my opinion, if you guys want to throw any accomplishments my way on this storm (and really, you don't have to lol), it should be moreso for sniffing out the possibility of a storm in this timeframe over a week ago and then keeping you guys informed step-by-step as the storm became more and more likely to affect Lake Orion (of course, with many twists and turns in this case). I do not feel the actual snow day prediction will be very hard. Unless an absolute disaster happens w/ regards to accumulations, I feel you guys have a great shot at a snow day on Monday. Everything from the large amount of snow that will fall, to the sheet of ice on the back roads & subdivision roads due to the rain freezing over, to the poor visibility, to the extremely low wind chills all support a snow day. I will therefore give Monday a snow day grade of "A".
Once again, I'm very sorry I didn't get this up earlier. As always, feel free to leave questions/comments in the comment box below. The upside of this post getting posted later than expected is that I used the extra time to study more for my exams, meaning that I may put out an extra update tomorrow afternoon before my final snow day prediction which will be posted exactly at 7:30 p.m. Eastern Time (and that may be coming in video form if I feel that ambitious).
Saturday, December 11, 2010
No big update but
after the latest set of forecast model runs, I am now highly confident that Lake Orion will see 5-9" of snow on Sunday & Sunday Night. Near blizzard conditions are also likely. Due to this I think there is a good chance of a snow day for you guys on Monday, although it is not a sure thing yet. I also believe you guys will be placed in a Winter Storm Watch later tonight.
My big update & final snowfall map for all of SE Michigan will come around 7:00 p.m. tomorrow. Final snow day prediction will come sometime Sunday Afternoon/Evening.
My big update & final snowfall map for all of SE Michigan will come around 7:00 p.m. tomorrow. Final snow day prediction will come sometime Sunday Afternoon/Evening.
Friday, December 10, 2010
Sunday's Storm Just Got Even More Complex
When all is said and done, no matter what happens, I don't think Sunday's storm will be one that I, or any other forecaster, will look back on and say: "Wow...I called that one correctly from a long way out." I know looking back on my posts, I was initially unconfident one way or the other. I then became more confident about a snowstorm for SE Michigan. From there, the confidence faded, reaching a low last night when I said that a lot of the precipitation would likely fall as rain, and SE Michigan would likely get only advisory level snowfall, if that. Being that at the time I wrote that post, we were only 60 hours out from the storm, I thought that would be the end of it. It looked like this storm would likely track too far north to give SE Michigan any significant snowfall.
But wait. This morning's model runs came in, and with them comes more hope that this storm will track far enough south to give SE Michigan the potentially significant snowfall that I thought you guys would be sure to see earlier in the stages of tracking this storm. I'm again less certain than I was last night. For being less than 48 hours out from the initial stages of this storm, I can say this might be the most uncertain storm I have ever followed. However, being that we are less than 48 hours out, it's really time to start leaning one way or another w/ regards to how much snow I think you guys are going to get. So, first let's take a look at some forecast models. From there, I will attempt to explain how I will make my forecast for this complex storm system. Finally, I will start to explain the chances for a snow day with this storm. With no further buildup, here we go:
GFS:
The latest run of the GFS has the low pressure system tracking from Chicago to Detroit. This is further south than what this model showed last night, when it had the low pressure system tracking from Milwaukee to Saginaw. This model was one of the more favorable ones for snow in SE Michigan in the first place, and it has only gotten more favorable since then, as it now shows almost all of SE Michigan getting predominantly snow for the entire event. In addition, this model now shows almost all of SE Michigan getting in on some good wraparound snow action, which would boost snow accumulations. As crazy as it sounds, I'm fairly certain that nearly all of SE Michigan would be in for a Winter Storm Warning criteria event if the GFS verified. It shows a long duration snow event from Sunday Morning continuing through early Monday Morning. Obviously this timeframe would be good for a snow day. The image below shows the wraparound band of snow hitting MI Sunday Evening. Note the strong pressure gradient (tightly packed black lines) which would result in strong winds.
ECMWF:
One of the most remarkable southward shifting models has been the ECMWF. The ECMWF has been locked into a northern solution for days, and last night showed a low pressure track from Milwaukee to Saginaw, with much of SE Michigan dealing with precipitation type issues. However, this morning's run of the ECMWF also shifted south, with the low pressure system moving from the Wisconsin/Illinois border to Detroit. I really can't believe I'm saying this, but looking at the data it also appears as though the ECMWF has a nice backside band of snow (the graphics haven't updated yet but the statistical data for the model has) which would result in borderline Winter Storm Warning criteria accumulations.
NAM:
I trust this model a lot in the short range, which is why I am still worried that it still has this low pressure system tracking from Milwaukee to Alpena, as it did last night. This is one of the main things that has me going against a big winter storm affecting SE Michigan this weekend. If the NAM's solution verified, most of SE Michigan would likely be looking at precipitation type issues and Winter Weather Advisory criteria snows at best, (a) because of increased precipitation type issues, and (b) because of the lack of good backside snows unlike what is shown on the GFS and ECMWF. In fact, in the image below, you can clearly see that the low pressure system and accompanying backside band of snow are well north of what is shown on the GFS. And, take my word for it, also north of what is shown on the ECMWF. When the NAM and ECMWF have a similar solution, as they did last night, it is difficult to forecast against them. However, now that they have different solutions, forecasting this system becomes very complex, as both models are usually deadly accurate at this range. In this case though, one of them will be very wrong. The question is, which one?
GGEM:
The GGEM is the furthest south of the models, with the low tracking from Gary, IN to Toledo, OH to Erie, PA. With this model, SE Michigan would likely stay all snow and get some good backside accumulations.
NMM:
The NMM is a High-Resolution model that I like to take a look at inside of 48 hours. This model also goes north, with a low pressure system tracking from Milwaukee to Saginaw, resulting in less snow for SE Michigan.
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This storm is truly a nightmare to forecast. There are two distinct camps of models at this time, the GFS/ECMWF/GGEM camp which has the low pressure system tracking south, and the NAM/Hi-Res model camp, which has the low pressuer system tracking north. Whichever one ends up being correct will affect the storm total accumulations in an extreme way. If the NAM/Hi-Res camp is correct, then much of the precipitation associated with this storm would come in a front end thump of rain/snow resulting in likely only 2-3" for SE Michigan. If the GFS/ECMWF/GGEM camp is correct, then not only would much of the front end thump of precipitation be snow, but SE Michigan would also likely get in the heavy snow on the backside of the low. Snow ratios would be high, allowing for efficient accumulation. In addition, winds would be very strong allowing the snow to blow & drift around. A lot more accumulation would fall, and there would be major blowing & drifting. Simply put, if the first solution happens, you guys would likely not get a snow day. If the second solution happens, you guys likely would get a snow day. It's extremely tough to favor one solution over the other at this time, but in the short range I'm a believer in trends, and I'm really starting to think this will end up tracking far enough to the south to give much of SE Michigan some good accumulations. Therefore, I will up my forecast accumulations for Lake Orion with this storm to 4-8", but also mention that there is a high bust potential with this storm. I will also upgrade the snow day grade to a C (50/50 chance, will increase or decrease as time gets closer). I really believe that the final snow day call will be fairly easy. If you guys get in on the backside snow bands, you'll probably get a snow day, and if you don't, you won't. But while I favor you guys getting in on the backside snow, I'm far from certain on it happening, so I will only upgrade the snow day grade to a "C" for now.
My next post will come tomorrow evening and this one will have a snowfall map, and in all likelihood, a lot more certainty on what will actualy happen. If I had to sum up my thoughts on this storm in one sentence right now, it would be: As opposed to last night, I am leaning towards SE Michigan getting a significant winter storm on Sunday, but it is far from certain.
One thing is for sure, this has been one of the craziest storms I have ever followed. As always, feel free to leave questions/comments in the comments section below.
But wait. This morning's model runs came in, and with them comes more hope that this storm will track far enough south to give SE Michigan the potentially significant snowfall that I thought you guys would be sure to see earlier in the stages of tracking this storm. I'm again less certain than I was last night. For being less than 48 hours out from the initial stages of this storm, I can say this might be the most uncertain storm I have ever followed. However, being that we are less than 48 hours out, it's really time to start leaning one way or another w/ regards to how much snow I think you guys are going to get. So, first let's take a look at some forecast models. From there, I will attempt to explain how I will make my forecast for this complex storm system. Finally, I will start to explain the chances for a snow day with this storm. With no further buildup, here we go:
GFS:
The latest run of the GFS has the low pressure system tracking from Chicago to Detroit. This is further south than what this model showed last night, when it had the low pressure system tracking from Milwaukee to Saginaw. This model was one of the more favorable ones for snow in SE Michigan in the first place, and it has only gotten more favorable since then, as it now shows almost all of SE Michigan getting predominantly snow for the entire event. In addition, this model now shows almost all of SE Michigan getting in on some good wraparound snow action, which would boost snow accumulations. As crazy as it sounds, I'm fairly certain that nearly all of SE Michigan would be in for a Winter Storm Warning criteria event if the GFS verified. It shows a long duration snow event from Sunday Morning continuing through early Monday Morning. Obviously this timeframe would be good for a snow day. The image below shows the wraparound band of snow hitting MI Sunday Evening. Note the strong pressure gradient (tightly packed black lines) which would result in strong winds.
ECMWF:
One of the most remarkable southward shifting models has been the ECMWF. The ECMWF has been locked into a northern solution for days, and last night showed a low pressure track from Milwaukee to Saginaw, with much of SE Michigan dealing with precipitation type issues. However, this morning's run of the ECMWF also shifted south, with the low pressure system moving from the Wisconsin/Illinois border to Detroit. I really can't believe I'm saying this, but looking at the data it also appears as though the ECMWF has a nice backside band of snow (the graphics haven't updated yet but the statistical data for the model has) which would result in borderline Winter Storm Warning criteria accumulations.
NAM:
I trust this model a lot in the short range, which is why I am still worried that it still has this low pressure system tracking from Milwaukee to Alpena, as it did last night. This is one of the main things that has me going against a big winter storm affecting SE Michigan this weekend. If the NAM's solution verified, most of SE Michigan would likely be looking at precipitation type issues and Winter Weather Advisory criteria snows at best, (a) because of increased precipitation type issues, and (b) because of the lack of good backside snows unlike what is shown on the GFS and ECMWF. In fact, in the image below, you can clearly see that the low pressure system and accompanying backside band of snow are well north of what is shown on the GFS. And, take my word for it, also north of what is shown on the ECMWF. When the NAM and ECMWF have a similar solution, as they did last night, it is difficult to forecast against them. However, now that they have different solutions, forecasting this system becomes very complex, as both models are usually deadly accurate at this range. In this case though, one of them will be very wrong. The question is, which one?
GGEM:
The GGEM is the furthest south of the models, with the low tracking from Gary, IN to Toledo, OH to Erie, PA. With this model, SE Michigan would likely stay all snow and get some good backside accumulations.
NMM:
The NMM is a High-Resolution model that I like to take a look at inside of 48 hours. This model also goes north, with a low pressure system tracking from Milwaukee to Saginaw, resulting in less snow for SE Michigan.
---
This storm is truly a nightmare to forecast. There are two distinct camps of models at this time, the GFS/ECMWF/GGEM camp which has the low pressure system tracking south, and the NAM/Hi-Res model camp, which has the low pressuer system tracking north. Whichever one ends up being correct will affect the storm total accumulations in an extreme way. If the NAM/Hi-Res camp is correct, then much of the precipitation associated with this storm would come in a front end thump of rain/snow resulting in likely only 2-3" for SE Michigan. If the GFS/ECMWF/GGEM camp is correct, then not only would much of the front end thump of precipitation be snow, but SE Michigan would also likely get in the heavy snow on the backside of the low. Snow ratios would be high, allowing for efficient accumulation. In addition, winds would be very strong allowing the snow to blow & drift around. A lot more accumulation would fall, and there would be major blowing & drifting. Simply put, if the first solution happens, you guys would likely not get a snow day. If the second solution happens, you guys likely would get a snow day. It's extremely tough to favor one solution over the other at this time, but in the short range I'm a believer in trends, and I'm really starting to think this will end up tracking far enough to the south to give much of SE Michigan some good accumulations. Therefore, I will up my forecast accumulations for Lake Orion with this storm to 4-8", but also mention that there is a high bust potential with this storm. I will also upgrade the snow day grade to a C (50/50 chance, will increase or decrease as time gets closer). I really believe that the final snow day call will be fairly easy. If you guys get in on the backside snow bands, you'll probably get a snow day, and if you don't, you won't. But while I favor you guys getting in on the backside snow, I'm far from certain on it happening, so I will only upgrade the snow day grade to a "C" for now.
My next post will come tomorrow evening and this one will have a snowfall map, and in all likelihood, a lot more certainty on what will actualy happen. If I had to sum up my thoughts on this storm in one sentence right now, it would be: As opposed to last night, I am leaning towards SE Michigan getting a significant winter storm on Sunday, but it is far from certain.
One thing is for sure, this has been one of the craziest storms I have ever followed. As always, feel free to leave questions/comments in the comments section below.
Just an extremely tough storm to forecast...
I'll be honest, storms like these really make me wish I hadn't brought back the blog for another year, because this is one of the most difficult storms I will ever attempt to forecast. It's 2 days out and there is still an extremely high bust potential for SE Michigan. However, it's not like I won't be forecasting difficult storms for the rest of my life, so I'll get to telling you guys my latest thoughts on this. If I'm right, it's a learning experience, and if I'm wrong, it's a learning experience. So let's go. This post tonight will be a quick one, but I will have 3 more posts out. I would do 2 a day but exam week is next week for me so I need to devote a lot of time to studying. The 3 remaining posts will be out around 5:00 p.m. tomorrow, around 8:00 p.m. Saturday, and my final prediction will come around 9:00 p.m. Saturday.
I do need to get to bed tonight, so there isn't much time for an in-depth look at the models. The conclusion I've come to, however, is that SE Michigan is most likely looking at precipitation starting as rain on Sunday Morning, before turning to snow. The precipitation will then end by Sunday Evening. In my opinion, it is looking fairly bleak for a snow day on Monday. First, I now expect only 2-6" of snow to fall due to rain likely mixing in for part of the storm. The track of this storm has trended well north, allowing for warmer temperatures and precipitation type issues. Therefore, the amount of snow that is going to fall will be marginal for a snow day. In addition this storm keeps trending faster, and I am now expecting the bulk of the precipitation to end by early Sunday evening, which may certainly be enough time to clear the roads. Therefore, I will tentatively set the snow day grade to a D (below average chance but not totally hopeless) for Monday.
I am slightly disappointed in this, as the models seemed to be really zoning in on a nice snowstorm for SE Michigan a couple of nights ago. Hindsight is 20/20 though, and looking back, they were way to inconsistent for me to say things were looking good. That has been the only thing I regret so far with forecasting this storm, as other than that post, I mentioned that the models were all over the place, which they have been. Truly a tough storm to forecast.
I apologize for such a short post but I have to get to bed. Leave your questions/comments below and I'll get to them tomorrow before my next post which will be up at around 5:00 p.m.
I do need to get to bed tonight, so there isn't much time for an in-depth look at the models. The conclusion I've come to, however, is that SE Michigan is most likely looking at precipitation starting as rain on Sunday Morning, before turning to snow. The precipitation will then end by Sunday Evening. In my opinion, it is looking fairly bleak for a snow day on Monday. First, I now expect only 2-6" of snow to fall due to rain likely mixing in for part of the storm. The track of this storm has trended well north, allowing for warmer temperatures and precipitation type issues. Therefore, the amount of snow that is going to fall will be marginal for a snow day. In addition this storm keeps trending faster, and I am now expecting the bulk of the precipitation to end by early Sunday evening, which may certainly be enough time to clear the roads. Therefore, I will tentatively set the snow day grade to a D (below average chance but not totally hopeless) for Monday.
I am slightly disappointed in this, as the models seemed to be really zoning in on a nice snowstorm for SE Michigan a couple of nights ago. Hindsight is 20/20 though, and looking back, they were way to inconsistent for me to say things were looking good. That has been the only thing I regret so far with forecasting this storm, as other than that post, I mentioned that the models were all over the place, which they have been. Truly a tough storm to forecast.
I apologize for such a short post but I have to get to bed. Leave your questions/comments below and I'll get to them tomorrow before my next post which will be up at around 5:00 p.m.
Thursday, December 9, 2010
Quick Update
If you're looking for an in-depth discussion of the storm, scroll down to the next post...this post is simply a quick update to say that my hunch about favoring the northern solution seems to be correct, as the GFS model has moved way north. In addition, the NAM model is coming into a useful range, and it is also similar to the GFS & ECMWF. So for now, the northern solution looks to be the way to go. In general, this is good for SE Michigan to see snow, but if this storm track is what ends up happening, we will certainly have to look out for rain to mix with the snow in some places and cut down on accumulations.
In addition, the strength of this system is still in question, as the GFS still has a weak disorganized system, while the NAM and ECMWF have a stronger, more organized system. This would likely lead to higher snowfall accumulations on the NAM & ECMWF, but since a stronger system brings up warmer air, also more potential for rain as opposed to snow. So, there are still certainly issues to figure out. But it looks as though the models are starting to lock in on a storm track that has a good shot of at least bringing a plowable snowstorm to SE Michigan on Sunday.
At this point, the main thing that you guys have to be concerned about is the potential for temperatures to be too warm for any significant snow to fall. This is starting to become a significant concern that will have to be addressed in tomorrow's post. Anyways I'll go in detail more tomorrow afternoon. And like I said, if you want a much more polished post (albeit with old model runs), scroll down below.
As always, feel free to leave questions/comments in the comment section below.
In addition, the strength of this system is still in question, as the GFS still has a weak disorganized system, while the NAM and ECMWF have a stronger, more organized system. This would likely lead to higher snowfall accumulations on the NAM & ECMWF, but since a stronger system brings up warmer air, also more potential for rain as opposed to snow. So, there are still certainly issues to figure out. But it looks as though the models are starting to lock in on a storm track that has a good shot of at least bringing a plowable snowstorm to SE Michigan on Sunday.
At this point, the main thing that you guys have to be concerned about is the potential for temperatures to be too warm for any significant snow to fall. This is starting to become a significant concern that will have to be addressed in tomorrow's post. Anyways I'll go in detail more tomorrow afternoon. And like I said, if you want a much more polished post (albeit with old model runs), scroll down below.
As always, feel free to leave questions/comments in the comment section below.
Wednesday, December 8, 2010
Well, just when everything seemed well...
Everything seemed to be coming into agreement last night, with most models showing SE Michigan getting a nice snowstorm on Sunday. I was one more set of similar forecast model runs from fully jumping on the snowstorm bandwagon, but then the latest run of the GFS model went way south of its previous run. In addition, the GGEM model went a little further south as well. Meanwhile, the ECMWF model is back to it's far northern solution. This storm is turning out to be one of the more interesting/challenging storms I've seen in the few years that I've been seriously following the weather. We're essentially 4 days out from this storm impacting SE Michigan, and there is still very little agreement among the models that I look at. Both solutions are perfectly plausible, yet one or both of them are going to be incorrect, which from a weather lover's standpoint, is fascinating. So, let's take a look at what the models show and what this could mean for SE Michigan...
Note that if you don't want to read the whole thing (because it's a book), the last two paragraphs adequately summarize everything.
The 12z GFS has the low pressure system tracking from Nashville, TN to Raleigh, NC to New York, NY. Although SE Michigan would still get a few inches of snow with this track, the best snowfall accumulations would be to your south. The image below shows the GFS's storm total precipitation, and as you can see, the highest amounts are to the south.
The 12z ECMWF is WAY further north, tracking the low pressure system from Des Moines, IA to Chicago, IL to Detroit, MI. SE Michigan would get a lot of precipitation from this track, but there would be the issue of rain mixing in with the snow, especially south of I-696. Areas that did mix with rain would obviously have their accumulations cut, but areas that avoided that would pick up a lot of snow. If this track happened, figuring out which areas would mix with rain would likely be a nowcasting situation, requiring the use of short-range models and observations once the storm started. The image below shows where the ECMWF has the low pressure system on Sunday Morning.
Finally, the 12z GGEM has the low tracking from around Paducah, KY to around Cincinnati, OH to around Pittsburgh, PA. This track would allow much of SE Michigan to get moderate-heavy snow, but Lake Orion would be cutting it very very close to being too far north to get significant accumulations. The image below shows where the GGEM has the low pressure system on Sunday Morning.
The fundamental difference that I see in all three models was the amount of time that it took each of them to close off the upper-level low. While the ECMWF closes off the upper-level low quickly (by the time it gets into Iowa), the GFS and GGEM keep the energy weak, allowing it to move further south, and don't close it off until it's well east of the Great Lakes states. The end result of this (the reasoning behind it is complicated to explain) is that the reason the ECMWF is much further north than the GGEM and the GFS is because it closes the low off so early relative to the other two models.
The images below show, in order, where the GFS, ECMWF, and GGEM close off the upper level low. Note the large difference in the areas where the low closes off.
The GFS closes it off in Canada.
The ECMWF closes it off all the way back in the Midwest.
The GGEM closes it off in the Mid Atlantic.
While all three solutions are fully believable at this point in time, I've been thinking about this lately, and I'm really starting to favor the stronger/further north solution of the ECMWF. As you know if you've been reading my posts on this storm, this is a fairly strong/dynamic system. With this in mind, I tend to believe that something closer to the ECMWF is likely to happen. In my experience following these storms, I just don't remember seeing these dynamic systems take as long to get their act together as this one has on the GFS and GGEM. It's entirely possible that something like what is shown on the GFS and GGEM could happen, but I just feel that the ECMWF/northern solution is more likely to happen.
To summarize, there is a large spread of solutions among the models I look at. The GFS has SE Michigan receiving little snow. The GGEM has SE Michigan receiving a decent amount of snow, but it would be a very close call (if it went even a little more south, Lake Orion would be largely left out of the best snow accumulations). The ECMWF has SE Michigan receiving a lot of precipitation, but mixing issues would be present, especially south of I-696. The reason why these models are showing such different solutions is that the GFS and GGEM take way longer to close off the upper level low than the ECMWF, resulting in a further south track. Due to reasons mentioned in the previous paragraph, I feel the ECMWF solution is the most likely, and that is the solution I am currently leaning towards. However, there is obviously still a lot of uncertainty.
If it all works out, SE Michigan could definitely see a great snowstorm with a high likelihood of a snow day on Monday. However, there is a higher than average bust potential with this system than there normally is at 3.5-4 days out. Issues such as the storm tracking too far south resulting in SE Michigan being north of the best snow accumulations, and on the other hand, the storm tracking too far north resulting in SE Michigan dealing with mixed precipitation could both greatly diminish the snow day possibilities. We can only hope that the models come to a better agreement soon so I can start discussing the likelihood of a snow day, but at this time I am still unsure as to what exactly will happen, and am in fact less confident than I was in my last post. This is an extremely interesting storm to follow, and I'll likely have my next post up by the time you leave for school tomorrow morning.
Until then, feel free to leave questions/comments in the comments section below.
Note that if you don't want to read the whole thing (because it's a book), the last two paragraphs adequately summarize everything.
The 12z GFS has the low pressure system tracking from Nashville, TN to Raleigh, NC to New York, NY. Although SE Michigan would still get a few inches of snow with this track, the best snowfall accumulations would be to your south. The image below shows the GFS's storm total precipitation, and as you can see, the highest amounts are to the south.
The 12z ECMWF is WAY further north, tracking the low pressure system from Des Moines, IA to Chicago, IL to Detroit, MI. SE Michigan would get a lot of precipitation from this track, but there would be the issue of rain mixing in with the snow, especially south of I-696. Areas that did mix with rain would obviously have their accumulations cut, but areas that avoided that would pick up a lot of snow. If this track happened, figuring out which areas would mix with rain would likely be a nowcasting situation, requiring the use of short-range models and observations once the storm started. The image below shows where the ECMWF has the low pressure system on Sunday Morning.
Finally, the 12z GGEM has the low tracking from around Paducah, KY to around Cincinnati, OH to around Pittsburgh, PA. This track would allow much of SE Michigan to get moderate-heavy snow, but Lake Orion would be cutting it very very close to being too far north to get significant accumulations. The image below shows where the GGEM has the low pressure system on Sunday Morning.
The fundamental difference that I see in all three models was the amount of time that it took each of them to close off the upper-level low. While the ECMWF closes off the upper-level low quickly (by the time it gets into Iowa), the GFS and GGEM keep the energy weak, allowing it to move further south, and don't close it off until it's well east of the Great Lakes states. The end result of this (the reasoning behind it is complicated to explain) is that the reason the ECMWF is much further north than the GGEM and the GFS is because it closes the low off so early relative to the other two models.
The images below show, in order, where the GFS, ECMWF, and GGEM close off the upper level low. Note the large difference in the areas where the low closes off.
The GFS closes it off in Canada.
The ECMWF closes it off all the way back in the Midwest.
The GGEM closes it off in the Mid Atlantic.
While all three solutions are fully believable at this point in time, I've been thinking about this lately, and I'm really starting to favor the stronger/further north solution of the ECMWF. As you know if you've been reading my posts on this storm, this is a fairly strong/dynamic system. With this in mind, I tend to believe that something closer to the ECMWF is likely to happen. In my experience following these storms, I just don't remember seeing these dynamic systems take as long to get their act together as this one has on the GFS and GGEM. It's entirely possible that something like what is shown on the GFS and GGEM could happen, but I just feel that the ECMWF/northern solution is more likely to happen.
To summarize, there is a large spread of solutions among the models I look at. The GFS has SE Michigan receiving little snow. The GGEM has SE Michigan receiving a decent amount of snow, but it would be a very close call (if it went even a little more south, Lake Orion would be largely left out of the best snow accumulations). The ECMWF has SE Michigan receiving a lot of precipitation, but mixing issues would be present, especially south of I-696. The reason why these models are showing such different solutions is that the GFS and GGEM take way longer to close off the upper level low than the ECMWF, resulting in a further south track. Due to reasons mentioned in the previous paragraph, I feel the ECMWF solution is the most likely, and that is the solution I am currently leaning towards. However, there is obviously still a lot of uncertainty.
If it all works out, SE Michigan could definitely see a great snowstorm with a high likelihood of a snow day on Monday. However, there is a higher than average bust potential with this system than there normally is at 3.5-4 days out. Issues such as the storm tracking too far south resulting in SE Michigan being north of the best snow accumulations, and on the other hand, the storm tracking too far north resulting in SE Michigan dealing with mixed precipitation could both greatly diminish the snow day possibilities. We can only hope that the models come to a better agreement soon so I can start discussing the likelihood of a snow day, but at this time I am still unsure as to what exactly will happen, and am in fact less confident than I was in my last post. This is an extremely interesting storm to follow, and I'll likely have my next post up by the time you leave for school tomorrow morning.
Until then, feel free to leave questions/comments in the comments section below.
Confidence Increasing On Sunday Storm
The two main forecast models that I look at, the GFS and ECMWF, have now largely come into agreement for the first time with regards to the track of the upcoming winter storm on Sunday. My confidence is increasing that this storm will have adverse impacts on SE Michigan, and here's why.
First, I'll look at the latest (00z) run of the GFS model. If you recall from my last post yesterday evening, this model was the one with the southernmost track. Since my last post, the GFS (and other models, as I'll get to shortly) no longer favors a transfer of energy from a primary low pressure system to a secondary low pressure system (if you want a more detailed explanation on this scroll down to my previous post). The latest run of the GFS now favor a single main low pressure system tracking from Paducah, Kentucky to Columbus, Ohio to Pittsburgh, Pennsylvania. This is usually a fairly ideal storm track for SE Michigan to receive good snowfall, and it looks like if that track happens for this storm, that will again be the case, as the GFS shows a period of Moderate/Heavy snow occuring from Sunday Morning through Sunday Evening. The image below shows the storm total precipitation from the latest run of the GFS. This is about 0.5" of liquid, which using the typical 10:1 snowfall ratio, would result in about 5" of snow. However, since temperatures would likely be fairly cold if this storm track took place, I am betting that snowfall ratios would be higher than normal, meaning more than 5" of snow would likely fall.
Next, I'll look at the latest (00z) run of the ECMWF model. As you may recall, as of my last blog post this model was the main outlier, showing a storm track from Chicago to Saginaw, which would result in a very sloppy rain/snow storm for SE Michigan, which would severely limit snow accumulations. I mentioned that I favored the GFS track over the ECMWF track, but that I was still unconfident. As it turns out, it appears that yesterdays GFS track will be closer to being correct than the ECMWF track (although neither of them will likely end up being perfectly correct). This is because, relative to yesterday, the ECMWF model has made a significant southward shift, and now also shows a significant snow storm for SE Michigan. The exact center of low pressure is fairly difficult to depict on the ECMWF, but I will say it likely tracks from Evansville, IN to Dayton, OH to Erie, PA. This is slightly north, but still fairly similar to, the track of the the latest GFS, and the ECMWF now also shows SE Michigan getting Moderate/Heavy snow all day Sunday. While I can't post images of precipitation from the ECMWF, I can say that it shows SE Michigan getting around 0.6" of liquid, which would translate to around 6" of snow using standard 10:1 snowfall ratios. While the ratios if the ECMWF track were to occur would be less than the ratios using the GFS track, they would still likely be above 10:1, meaning more than 6" of snow would likely fall.
Finally, I'd also like to mention two other models that I also take into consideration, the GGEM and UKMET. The GGEM model shows the storm tracking from Evansville, IN to Columbus, OH and also gives SE Michigan a significant snowstorm, as shown in the image below. The UKMET model is currently a large southern outlier, taking the system from Nashville, TN to Raleigh, NC...which is obviously significantly further south than the other three models I look at. For this reason, I doubt that track will happen, but it is something to keep in mind.
In summary, the forecast models seem to be coming into agreement on a potentially significant winter storm that could impact SE Michigan on Sunday. The main timeframe for snowfall would likely be from Early Sunday Morning through Early Sunday Evening. While this may not be the best timeframe to get a snow day on Monday, I do believe that IF this storm occurs as currently shown on most of the models (and that's still definitely not a sure thing), there would be a good chance of a snow day on Monday. This is because I believe that SE Michigan could possibly see totals well above 6", and also because I believe there will be a significant wind component with this storm system, which would lead to blowing and drifting of snow, and likely subzero wind chills. So, while a snow day is far from a sure thing at this point (and it never really is 5 days out), it's definitely something to keep an eye on. I still have some reservations w/ regards to this storm, but I am much more confident than I was in my last post.
I will likely have another post up tomorrow afternoon. Until then, feel free to leave questions/comments in the comments section below.
First, I'll look at the latest (00z) run of the GFS model. If you recall from my last post yesterday evening, this model was the one with the southernmost track. Since my last post, the GFS (and other models, as I'll get to shortly) no longer favors a transfer of energy from a primary low pressure system to a secondary low pressure system (if you want a more detailed explanation on this scroll down to my previous post). The latest run of the GFS now favor a single main low pressure system tracking from Paducah, Kentucky to Columbus, Ohio to Pittsburgh, Pennsylvania. This is usually a fairly ideal storm track for SE Michigan to receive good snowfall, and it looks like if that track happens for this storm, that will again be the case, as the GFS shows a period of Moderate/Heavy snow occuring from Sunday Morning through Sunday Evening. The image below shows the storm total precipitation from the latest run of the GFS. This is about 0.5" of liquid, which using the typical 10:1 snowfall ratio, would result in about 5" of snow. However, since temperatures would likely be fairly cold if this storm track took place, I am betting that snowfall ratios would be higher than normal, meaning more than 5" of snow would likely fall.
Next, I'll look at the latest (00z) run of the ECMWF model. As you may recall, as of my last blog post this model was the main outlier, showing a storm track from Chicago to Saginaw, which would result in a very sloppy rain/snow storm for SE Michigan, which would severely limit snow accumulations. I mentioned that I favored the GFS track over the ECMWF track, but that I was still unconfident. As it turns out, it appears that yesterdays GFS track will be closer to being correct than the ECMWF track (although neither of them will likely end up being perfectly correct). This is because, relative to yesterday, the ECMWF model has made a significant southward shift, and now also shows a significant snow storm for SE Michigan. The exact center of low pressure is fairly difficult to depict on the ECMWF, but I will say it likely tracks from Evansville, IN to Dayton, OH to Erie, PA. This is slightly north, but still fairly similar to, the track of the the latest GFS, and the ECMWF now also shows SE Michigan getting Moderate/Heavy snow all day Sunday. While I can't post images of precipitation from the ECMWF, I can say that it shows SE Michigan getting around 0.6" of liquid, which would translate to around 6" of snow using standard 10:1 snowfall ratios. While the ratios if the ECMWF track were to occur would be less than the ratios using the GFS track, they would still likely be above 10:1, meaning more than 6" of snow would likely fall.
Finally, I'd also like to mention two other models that I also take into consideration, the GGEM and UKMET. The GGEM model shows the storm tracking from Evansville, IN to Columbus, OH and also gives SE Michigan a significant snowstorm, as shown in the image below. The UKMET model is currently a large southern outlier, taking the system from Nashville, TN to Raleigh, NC...which is obviously significantly further south than the other three models I look at. For this reason, I doubt that track will happen, but it is something to keep in mind.
In summary, the forecast models seem to be coming into agreement on a potentially significant winter storm that could impact SE Michigan on Sunday. The main timeframe for snowfall would likely be from Early Sunday Morning through Early Sunday Evening. While this may not be the best timeframe to get a snow day on Monday, I do believe that IF this storm occurs as currently shown on most of the models (and that's still definitely not a sure thing), there would be a good chance of a snow day on Monday. This is because I believe that SE Michigan could possibly see totals well above 6", and also because I believe there will be a significant wind component with this storm system, which would lead to blowing and drifting of snow, and likely subzero wind chills. So, while a snow day is far from a sure thing at this point (and it never really is 5 days out), it's definitely something to keep an eye on. I still have some reservations w/ regards to this storm, but I am much more confident than I was in my last post.
I will likely have another post up tomorrow afternoon. Until then, feel free to leave questions/comments in the comments section below.
Monday, December 6, 2010
Small Storm Thursday Night. Bigger One Sunday?
Not much has changed since this time yesterday. SE Michigan is still looking at a weaker clipper system moving through the area Thursday Night, followed by a much stronger, but much more unpredictable storm on Sunday.
First I will mention the clipper. Earlier in the week, I was thinking that advisory level snows were possible with this storm system, but unfortunately for SE Michigan it has continued to trend further and further north on the forecast models, and it's just not looking like this will provide much more than 1-2" of snow on Thursday Night. To be honest, it's barely worth mentioning now, because although it's going to be the first snow SE Michigan will receive from an actual storm system as opposed to lake effect snow, it's not like it's going to give SE Michigan much more snow than some of the lake effect events you guys have received so far this year. I'll probably continue to update the forecast with this storm just for the heck of it, but really the main thing to focus on is a potentially significant storm on Sunday, which is what the next portion of this post will cover.
Again, over the past day the main medium-range forecast models (the GFS and ECMWF) have all continued to favor a strong low-pressure system affecting the Eastern U.S. around next Sunday. There is now enough consistency for me to fully believe that there will be a significant snow storm somewhere in the Eastern U.S. this Sunday. Obviously, the million-dollar question now becomes: Where will this storm track? The answer to this question will adversely affect what SE Michigan sees from this system.
As far as I see it, there are three main possibilities for where this storm will track. Option one has this storm bombing out near the East Coast, providing a nice snow storm for areas east of MI but leaving SE Michigan largely dry. Option two has the primary low pressure system moving to the east through Illinois, Indiana, Ohio, etc...with the primary low eventually occluding and transferring energy to a secondary low, which would move up through Central PA & NY. This is the scenario to hope for if you want a snow day. This scenario would likely give SE Michigan at least several inches of snow, with Winter Storm Warning criteria snowfalls entirely possible. In addition, as the secondary low rapidly intensifies, high wind & blowing/drifting snow would certainly become an issue. Option three has the primary low becoming stronger, which would result in a further west track with the likely result in SE Michigan being a sloppy mix of rain/snow.
At this time I believe it's prudent to look at some forecast models & at least try to get an idea of which track I might favor.
First, I'll start off by looking at the 12z GFS. The 12z GFS has some energy diving SE from the Dakotas. This energy eventually phases with the digging polar jet, with the result being a primary low pressure system that gets to around Cincinnati before transferring its energy to a secondary low pressure system which tracks from SE VA to Central NY. Yes, this is a rather complicated storm system with the transfer of energy...so I understand if it's tough to follow. The result is a very good storm system for the I-80 corridor of Northern IL, IN, and OH, with MI missing out on the best snows, but still getting several inches. In addition, winds would get very strong at the end of this storm and in the following days if this solution verified. Some images showing what happens are below:
1 a.m. Sunday
7 a.m. Sunday
1 p.m. Sunday
7 p.m. Sunday
The next model to look at is the 12z ECMWF. Although I do have access to images from this model I can't repost them, but I will describe what it shows. Essentially, the main difference between the ECMWF and GFS is that the ECMWF has the primary low pressure system moving much further north than the GFS, and it also does not feature an energy transfer. The result is a low pressure system that tracks from Iowa to Chicago to Central MI, and while SE Michigan would see a lot of precipitation from this track, a lot of it would fall as rain. I doubt there would be much accumulating snow, and what would accumulate would likely be washed away as precipitation changes over to rain.
So, obviously there is a significant amount of disagreement among the forecast models. At this time I would favor the GFS track as the GFS has been outperforming the ECMWF w/ regards to accuracy in recent weeks. However, this by no means is equal to me calling for a guaranteed snowstorm for SE Michigan on Sunday & Sunday Night. If things work out correctly, there could definitely be a big snowstorm for SE Michigan, with a snow day being possible next Monday, but there's still a lot of uncertainty. I will probably have another post up tomorrow night.
First I will mention the clipper. Earlier in the week, I was thinking that advisory level snows were possible with this storm system, but unfortunately for SE Michigan it has continued to trend further and further north on the forecast models, and it's just not looking like this will provide much more than 1-2" of snow on Thursday Night. To be honest, it's barely worth mentioning now, because although it's going to be the first snow SE Michigan will receive from an actual storm system as opposed to lake effect snow, it's not like it's going to give SE Michigan much more snow than some of the lake effect events you guys have received so far this year. I'll probably continue to update the forecast with this storm just for the heck of it, but really the main thing to focus on is a potentially significant storm on Sunday, which is what the next portion of this post will cover.
Again, over the past day the main medium-range forecast models (the GFS and ECMWF) have all continued to favor a strong low-pressure system affecting the Eastern U.S. around next Sunday. There is now enough consistency for me to fully believe that there will be a significant snow storm somewhere in the Eastern U.S. this Sunday. Obviously, the million-dollar question now becomes: Where will this storm track? The answer to this question will adversely affect what SE Michigan sees from this system.
As far as I see it, there are three main possibilities for where this storm will track. Option one has this storm bombing out near the East Coast, providing a nice snow storm for areas east of MI but leaving SE Michigan largely dry. Option two has the primary low pressure system moving to the east through Illinois, Indiana, Ohio, etc...with the primary low eventually occluding and transferring energy to a secondary low, which would move up through Central PA & NY. This is the scenario to hope for if you want a snow day. This scenario would likely give SE Michigan at least several inches of snow, with Winter Storm Warning criteria snowfalls entirely possible. In addition, as the secondary low rapidly intensifies, high wind & blowing/drifting snow would certainly become an issue. Option three has the primary low becoming stronger, which would result in a further west track with the likely result in SE Michigan being a sloppy mix of rain/snow.
At this time I believe it's prudent to look at some forecast models & at least try to get an idea of which track I might favor.
First, I'll start off by looking at the 12z GFS. The 12z GFS has some energy diving SE from the Dakotas. This energy eventually phases with the digging polar jet, with the result being a primary low pressure system that gets to around Cincinnati before transferring its energy to a secondary low pressure system which tracks from SE VA to Central NY. Yes, this is a rather complicated storm system with the transfer of energy...so I understand if it's tough to follow. The result is a very good storm system for the I-80 corridor of Northern IL, IN, and OH, with MI missing out on the best snows, but still getting several inches. In addition, winds would get very strong at the end of this storm and in the following days if this solution verified. Some images showing what happens are below:
1 a.m. Sunday
7 a.m. Sunday
1 p.m. Sunday
7 p.m. Sunday
The next model to look at is the 12z ECMWF. Although I do have access to images from this model I can't repost them, but I will describe what it shows. Essentially, the main difference between the ECMWF and GFS is that the ECMWF has the primary low pressure system moving much further north than the GFS, and it also does not feature an energy transfer. The result is a low pressure system that tracks from Iowa to Chicago to Central MI, and while SE Michigan would see a lot of precipitation from this track, a lot of it would fall as rain. I doubt there would be much accumulating snow, and what would accumulate would likely be washed away as precipitation changes over to rain.
So, obviously there is a significant amount of disagreement among the forecast models. At this time I would favor the GFS track as the GFS has been outperforming the ECMWF w/ regards to accuracy in recent weeks. However, this by no means is equal to me calling for a guaranteed snowstorm for SE Michigan on Sunday & Sunday Night. If things work out correctly, there could definitely be a big snowstorm for SE Michigan, with a snow day being possible next Monday, but there's still a lot of uncertainty. I will probably have another post up tomorrow night.
Sunday, December 5, 2010
Two Upcoming Systems...
For fans of snow in SE Michigan, you will likely finally get the snow you have been hoping for in the next week. Two systems will likely affect the area...
System one is going to be a clipper system that will come out of Canada and then track through ND, MN, WI, and Northern MI. However, SE Michigan will definitely see some snow out of this system on Thursday Night & Friday Morning. It is not going to be a particularly strong system, and at this time it looks as if it will not have access to moisture from the Gulf of Mexico, so I don't believe this will be a very high impact event for SE Michigan. Right now I think around 2-4" of snow are likely on Thursday Night & Friday Morning. This is not enough snow for a snow day, but will be enough to cause disruptions to the Friday Morning commute, so be prepared for that. For being 4.5 days out, I have fairly high confidence that SE Michigan will see snow from this system, but I do not believe it will be a high impact event.
System two is the system that you will have to keep your eyes on w/ regards to snow days. There is good support among the models for a strong low pressure system to affect the Eastern U.S. around next Sunday or Monday. Depending on what happens in the upper levels of the atmosphere (and I will likely explain this further in the next few days), this storm could affect a variety of different places. The only real agreement among the models at this time is that there will be a strong storm somewhere. Some of the models have the storm mostly affecting the NE and missing SE Michigan. Some of the models have the storm cutting into the Great Lakes, which is a good storm track for SE Michgian. Another possibility is that the storm track could be too far to the west for SE Michigan to receive any significant snow, with most of the precipitation falling as rain. I am not confident enough to favor any of these scenarios at this time. While I do believe it is likely that someone in the Eastern U.S. will see a good snow event around next Sunday or Monday, I am not willing to make a prediction as to which areas will be affected.
As always, feel free to ask me questions or leave comments in the comments section.
System one is going to be a clipper system that will come out of Canada and then track through ND, MN, WI, and Northern MI. However, SE Michigan will definitely see some snow out of this system on Thursday Night & Friday Morning. It is not going to be a particularly strong system, and at this time it looks as if it will not have access to moisture from the Gulf of Mexico, so I don't believe this will be a very high impact event for SE Michigan. Right now I think around 2-4" of snow are likely on Thursday Night & Friday Morning. This is not enough snow for a snow day, but will be enough to cause disruptions to the Friday Morning commute, so be prepared for that. For being 4.5 days out, I have fairly high confidence that SE Michigan will see snow from this system, but I do not believe it will be a high impact event.
System two is the system that you will have to keep your eyes on w/ regards to snow days. There is good support among the models for a strong low pressure system to affect the Eastern U.S. around next Sunday or Monday. Depending on what happens in the upper levels of the atmosphere (and I will likely explain this further in the next few days), this storm could affect a variety of different places. The only real agreement among the models at this time is that there will be a strong storm somewhere. Some of the models have the storm mostly affecting the NE and missing SE Michigan. Some of the models have the storm cutting into the Great Lakes, which is a good storm track for SE Michgian. Another possibility is that the storm track could be too far to the west for SE Michigan to receive any significant snow, with most of the precipitation falling as rain. I am not confident enough to favor any of these scenarios at this time. While I do believe it is likely that someone in the Eastern U.S. will see a good snow event around next Sunday or Monday, I am not willing to make a prediction as to which areas will be affected.
As always, feel free to ask me questions or leave comments in the comments section.
Saturday, December 4, 2010
Very Quiet Start To Snow Season In SE Michigan
I haven't posted on here in a while, so with not much else to do at the moment it may be time for a pretty wide-ranging post. It's been a very quiet start to snow season in SE Michigan; usually you guys would see at least one storm that brings accumulation, but if I'm keeping track correctly, I don't believe you guys have seen over 1" of snow at once so far this year. So, there hasn't really been much worth blogging about, and unfortunately for snowstorm lovers, that will likely continue in the near future.
First of all, there is a clipper system that is currently moving southeast through the Upper Midwest. This system will give cities such as Chicago, Indianapolis, and Cincinnati their first notable snowfall of the year, but will be too far south to give SE Michigan any notable weather. So, that's a no go.
After that, the next thing you guys have to look forward to snow-wise are occasional snow showers in the early part of the schoolweek (Monday-Wednesday). Conditions on these days will be very similar to what you guys experienced earlier this week, with occasional snow showers and very minor accumulations of up to an inch on any given day.
The most interesting thing to me in the medium range is another clipper system that will affect SE Michigan around Friday. There is some disagreement in the models with this system, with one main model (the GFS), calling for a fairly moisture starved system that would likely only give you guys 1-2" of snow, while another main model (the ECMWF) is showing a fairly decent snowfall occurring on Thursday Night & Friday Morning. If the ECMWF's wetter solution pans out, then I bet you guys would likely see a Winter Weather Advisory, but we are still 6 days away from that potential event, and there is significant model disagreement, so I am very hesitant to feel too good about decent accumulations with this system, but they are a possibility. I will likely have a more detailed post focusing on this system up on Sunday Night or Monday when there will hopefully be more of a consensus among the models.
Finally, there are hints of a bigger storm system occurring around the 12th or 13th, but that's obviously in the extended range, so I won't bother covering that for now. For now, the bigger threat for a storm in this timeframe appears to be focused east of the Great Lakes, but it's the extended range, so things could always change...
As always, feel free to leave questions/comments in the comments section.
First of all, there is a clipper system that is currently moving southeast through the Upper Midwest. This system will give cities such as Chicago, Indianapolis, and Cincinnati their first notable snowfall of the year, but will be too far south to give SE Michigan any notable weather. So, that's a no go.
After that, the next thing you guys have to look forward to snow-wise are occasional snow showers in the early part of the schoolweek (Monday-Wednesday). Conditions on these days will be very similar to what you guys experienced earlier this week, with occasional snow showers and very minor accumulations of up to an inch on any given day.
The most interesting thing to me in the medium range is another clipper system that will affect SE Michigan around Friday. There is some disagreement in the models with this system, with one main model (the GFS), calling for a fairly moisture starved system that would likely only give you guys 1-2" of snow, while another main model (the ECMWF) is showing a fairly decent snowfall occurring on Thursday Night & Friday Morning. If the ECMWF's wetter solution pans out, then I bet you guys would likely see a Winter Weather Advisory, but we are still 6 days away from that potential event, and there is significant model disagreement, so I am very hesitant to feel too good about decent accumulations with this system, but they are a possibility. I will likely have a more detailed post focusing on this system up on Sunday Night or Monday when there will hopefully be more of a consensus among the models.
Finally, there are hints of a bigger storm system occurring around the 12th or 13th, but that's obviously in the extended range, so I won't bother covering that for now. For now, the bigger threat for a storm in this timeframe appears to be focused east of the Great Lakes, but it's the extended range, so things could always change...
As always, feel free to leave questions/comments in the comments section.
Sunday, November 21, 2010
Snow Showers Likely Thursday & Friday
Just a quick post to mention that a low pressure system that will move over the area on Thursday will be dragging a fairly strong cold front through SE Michigan by Thanksgiving morning. Behind this front, snow showers are likely on Thursday and Friday. Accumulations will be very minor but you will likely see snow during this timeframe.
Thursday, October 28, 2010
Forecast Review
Obviously, the severe weather portion of my forecast did not pan out. The problem was there was absolutely no instability over SE Michigan to bring the stronger winds down to the surface with the area of showers that moved over you guys on Tuesday afternoon. Obviously, this led to the forecast busting, despite the fact that there was a tornado watch over the area. There were a few tornado warnings and damaging wind reports with the showers, so I can't say that the forecast completely failed, but it still wasn't very good. Overall I'd give myself a "D" grade on the severe weather forecast.
As for the winds, I believe I did much better on those. About the only thing that I screwed up on, as far as I can tell, is that perhaps the peak wind gusts on Tuesday did not quite reach the 50mph I had forecasted. At the very least, they were still in the upper 40's though. Overall, I would give myself an "A" grade on the wind forecast.
Anyways, there will most likely be a fairly long break before my next post, as I seriously doubt there will be another low pressure system of this magnitude affecting you guys for a while, and climatologically, you guys are probably still a few weeks away from a storm system that will bring accumulating snow.
As for the winds, I believe I did much better on those. About the only thing that I screwed up on, as far as I can tell, is that perhaps the peak wind gusts on Tuesday did not quite reach the 50mph I had forecasted. At the very least, they were still in the upper 40's though. Overall, I would give myself an "A" grade on the wind forecast.
Anyways, there will most likely be a fairly long break before my next post, as I seriously doubt there will be another low pressure system of this magnitude affecting you guys for a while, and climatologically, you guys are probably still a few weeks away from a storm system that will bring accumulating snow.
Tuesday, October 26, 2010
"Nowcast" Update
The "nowcast" is in quotes because I can't really do true nowcast updates due to having classes and other stuff going on throughout the day today, but it is certainly worth mentioning that it now looks like the line of storms may affect the Lake Orion area a little earlier than I previously expected; somewhere between 1-3 p.m. Other than that the forecast remains on track with a good chance of some damaging winds and a chance of an isolated tornado when the line hits.
Monday, October 25, 2010
Extremely Strong Fall Storm To Have Adverse Impacts
I know I don't usually blog about anything but snow storms, but considering the potential implications of this storm for SE Michigan, I have decided to post about it.
Essentially, good divergence in the jet stream has caused a low pressure system to form over Kansas. Over the next 24 hours this low will move NE into Northern Minnesota and strengthen rapidly before moving into Canada. In fact, this could be the strongest low pressure system ever in Minnesota, as seen below. This system will have adverse impacts on Michigan weather over the next two days.
There will be two main impacts with regards to the weather from this system: severe thunderstorms and non-thunderstorm wind gusts. I will explain each one separately, then explain the combined impacts to everyday life.
Thunderstorms: This system will send a strong cold front through SE Michigan tomorrow afternoon. Right along this cold front will be a line of showers and embedded thunderstorms. Although there will not be too much instability in the atmosphere, with such strong upper level dynamics, not much instability will be needed to form a long line of severe thunderstorms. With 100+ mph winds just above ground level tomorrow, it won't take too much to mix some very strong winds down to the surface, and the line of thunderstorms will do the trick. Therefore, 60+ mph wind gusts are extremely likely when the line of storms hit, with some areas potentially receiving 75+ mph wind gusts. A widespread damaging wind event seems quite likely with this line of storms. In addition, there will be some rotation in the atmosphere so I feel that there will likely be some isolated tornadoes reported as well. Please note that this most likely will not be a widespread tornado outbreak. The tornado threat is secondary to the damaging wind threat, but is worth mentioning. The threat of hail with this line of storms is essentially zero. At this time I feel that the most likely timeframe for this line of storms to impact Lake Orion is between 2-5 p.m. tomorrow afternoon.
Non-Thunderstorm Wind Gusts: Even besides the line of thunderstorms, the pressure gradient will be very large due to the extremely low pressure in Minnesota. A large pressure gradient means that winds will be strong, and I expect sustained winds of 30-40 mph after the cold front moves through tomorrow, with wind gusts from 50-60 mph. Winds will calm down tomorrow night, but will increase again on Wednesday, with the expected winds being similar to those on Tuesday.
Impacts:
- Power Outages
- Trees being blown over, shingles being torn off roofs, etc.
- Unsecured items being blown around
Essentially the impacts will be similar to those of most severe thunderstorms with damaging wind gusts that move through. I will say I believe there will be fairly widespread wind damage due to (a) the extremely strong wind gusts that will likely accompany the line of storms (b) the length of the high wind event of SE Michigan. There is a nonzero chance that you guys could have school called off on Wednesday due to a power outage; however, predicting power outages is futile. It's not a high chance, but it is worth mentioning.
That's all for now, thanks for reading.
Essentially, good divergence in the jet stream has caused a low pressure system to form over Kansas. Over the next 24 hours this low will move NE into Northern Minnesota and strengthen rapidly before moving into Canada. In fact, this could be the strongest low pressure system ever in Minnesota, as seen below. This system will have adverse impacts on Michigan weather over the next two days.
There will be two main impacts with regards to the weather from this system: severe thunderstorms and non-thunderstorm wind gusts. I will explain each one separately, then explain the combined impacts to everyday life.
Thunderstorms: This system will send a strong cold front through SE Michigan tomorrow afternoon. Right along this cold front will be a line of showers and embedded thunderstorms. Although there will not be too much instability in the atmosphere, with such strong upper level dynamics, not much instability will be needed to form a long line of severe thunderstorms. With 100+ mph winds just above ground level tomorrow, it won't take too much to mix some very strong winds down to the surface, and the line of thunderstorms will do the trick. Therefore, 60+ mph wind gusts are extremely likely when the line of storms hit, with some areas potentially receiving 75+ mph wind gusts. A widespread damaging wind event seems quite likely with this line of storms. In addition, there will be some rotation in the atmosphere so I feel that there will likely be some isolated tornadoes reported as well. Please note that this most likely will not be a widespread tornado outbreak. The tornado threat is secondary to the damaging wind threat, but is worth mentioning. The threat of hail with this line of storms is essentially zero. At this time I feel that the most likely timeframe for this line of storms to impact Lake Orion is between 2-5 p.m. tomorrow afternoon.
Non-Thunderstorm Wind Gusts: Even besides the line of thunderstorms, the pressure gradient will be very large due to the extremely low pressure in Minnesota. A large pressure gradient means that winds will be strong, and I expect sustained winds of 30-40 mph after the cold front moves through tomorrow, with wind gusts from 50-60 mph. Winds will calm down tomorrow night, but will increase again on Wednesday, with the expected winds being similar to those on Tuesday.
Impacts:
- Power Outages
- Trees being blown over, shingles being torn off roofs, etc.
- Unsecured items being blown around
Essentially the impacts will be similar to those of most severe thunderstorms with damaging wind gusts that move through. I will say I believe there will be fairly widespread wind damage due to (a) the extremely strong wind gusts that will likely accompany the line of storms (b) the length of the high wind event of SE Michigan. There is a nonzero chance that you guys could have school called off on Wednesday due to a power outage; however, predicting power outages is futile. It's not a high chance, but it is worth mentioning.
That's all for now, thanks for reading.
Sunday, October 24, 2010
First Post Of The Season
Since I'm sure people will be coming over here due to the insanely bad "commercial" I posted, I guess it's probably time to make a post discussing what I will be doing RE: the blog for the 2010-11 school year. As most of you know, I have graduated from LOHS and, as some of you know, I am now a freshman at the University of Oklahoma pursuing a degree in meteorology. However, I would like to continue to gain experience in meteorology this year, and since all I am taking this year in school are gen-ed and basic meteorology courses, I have decided that it would be a good idea to keep myself "sharp" in meteorology by continuing to forecast snow amounts and snow days for the Lake Orion area. In addition, I had a few people still at LOHS tell me they would really appreciate it if I continued to predict snow days this year. Therefore, like I said after last winter was over, I will continue the blog this year, although this will most likely be the last year of the blog, as at some point I will have to move on from being a Lake Orion SuperSenior (I know, I know, it's sad).
I have two goals for the blog this year, one for accuracy and one for popularity. RE: Accuracy, I got every prediction right last year, so I would like to do that this year. RE: Popularity, I got ~ 10,000 views during February last year. Since the blog will run approximately 5 months (November thru March), I would like to get 50,000 views this year.
The approximate posting guidelines will be as follows: I almost certainly will not bother with posting about possible storms that are still farther than 7 days out, due to the fact that details change so much in the long range timeframe. Between 4-7 days out, I will usually post a brief 1-3 paragraph summary about possible storms. This will just be a simple overview, not very in-depth, perhaps with a few graphics. Between 0-3 days out, I will usually post a more in-depth discussion about possible storms, almost always with graphics, and with a snow day grade on the scale of A, B, C, D, E. In addition, once we get within ~48 hours of the storm, I will start posting maps with my forecasted snow totals for SE Michigan. In my final post before a storm hits, I will make a Yes/No prediction as to whether Lake Orion will get a snow day.
In addition to what I discuss in my posts, readers of this blog are welcome to use the comments section to post questions/comments. I moderate all comments because spammers have found out about this blog, but I will eventually check your comments and answer your questions.
Finally, if you would like to make a recommendation for additional things that I could include in this blog, feel free to notify me in some way. I have already received a request to do video forecasts, and will likely do a few of those during the season.
As always, thanks for reading.
-John Schlenner
I have two goals for the blog this year, one for accuracy and one for popularity. RE: Accuracy, I got every prediction right last year, so I would like to do that this year. RE: Popularity, I got ~ 10,000 views during February last year. Since the blog will run approximately 5 months (November thru March), I would like to get 50,000 views this year.
The approximate posting guidelines will be as follows: I almost certainly will not bother with posting about possible storms that are still farther than 7 days out, due to the fact that details change so much in the long range timeframe. Between 4-7 days out, I will usually post a brief 1-3 paragraph summary about possible storms. This will just be a simple overview, not very in-depth, perhaps with a few graphics. Between 0-3 days out, I will usually post a more in-depth discussion about possible storms, almost always with graphics, and with a snow day grade on the scale of A, B, C, D, E. In addition, once we get within ~48 hours of the storm, I will start posting maps with my forecasted snow totals for SE Michigan. In my final post before a storm hits, I will make a Yes/No prediction as to whether Lake Orion will get a snow day.
In addition to what I discuss in my posts, readers of this blog are welcome to use the comments section to post questions/comments. I moderate all comments because spammers have found out about this blog, but I will eventually check your comments and answer your questions.
Finally, if you would like to make a recommendation for additional things that I could include in this blog, feel free to notify me in some way. I have already received a request to do video forecasts, and will likely do a few of those during the season.
As always, thanks for reading.
-John Schlenner
Friday, February 26, 2010
Decent Event Today
The huge storm system affecting New England today is large enough to have adverse effects even for us back in SE Michigan. We should receive about 2-4" of snow today, with another inch possible tonight. Combine that with some very gusty winds, and we have a recipe for some very bad road conditions at times today. I expect a slow commute to school as a heavy band of snow moves through (schools in the more rural areas to our NE closed today). Anyways I figured this was worth a token mention, at least, as it will negatively impact the morning commute for sure and maybe the afternoon commute as well.
Monday, February 22, 2010
Tomorrow = Not So Good
The storm ended at around 4 p.m. today, and the main roads are already pretty good. I would expect that tonight the road crews will get to plowing the dirt roads, and by tomorrow morning, almost all of those will be cleared as well. By tomorrow morning, pretty much the only thing I would expect to not be plowed are the subdivisions and dead end side streets. This usually happens after a big storm, and we almost never get 2 snow days for a storm. Therefore, I am predicting that we will not have a snow day tomorrow.
Storm Total Snowfall
7.5" , within my 6-8" range.
Overall again am happy with how I forecasted this storm, predicted a snow day and we got one, predicted the total snowfall correctly...
Later I'll have my snow day prediction for tomorrow, I will probably predict no snow day but we do have a chance...
Overall again am happy with how I forecasted this storm, predicted a snow day and we got one, predicted the total snowfall correctly...
Later I'll have my snow day prediction for tomorrow, I will probably predict no snow day but we do have a chance...
Sunday, February 21, 2010
Final Call: 6-8" of snow...school?
Forecast Models:
All of the forecast models are in good agreement, so I will simply show the NAM and GFS, as they have the most detailed images.
NAM:
This image of the NAM shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the NAM shows a simulated radar image of the snow that will be affecting us tomorrow morning.
This image of the NAM shows storm total precipitation. This would give us around 7" of snow.
GFS:
This image of the GFS shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the GFS shows storm total precipitation. This would give us around 7" of snow.
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Snowfall Map:
The forecast models have been very consistent in showing the most precipitation falling in far SE Michigan. However, it now appears likely that the snow will mix with sleet in the early morning tomorrow near the Ohio Border. This will offset the higher precipitation amounts. In addition, there will be a lower snow-to-water ratio, which will also cut down on accumulations. Due to this, I will go with 5-7" for areas near the Ohio Border.
The most snow will likely fall between the I-94 and I-69 corridors. Here, lots of precipitation will still fall, but the snow will not mix with sleet tomorrow morning. Due to this, I will go with 6-8" for this area.
To the north of the I-69 corridor, precipitation amounts will start to taper off. Due to this, I will go with 5-7", and in the far northern counties, 4-6".
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Impacts From This Storm:
As you can see from the above radar image, this storm is on our doorstep. Snow will begin falling around midnight tonight, and increase in intensity as the night goes on. I would expect around 2" of snow to be on the ground by 6 a.m. tomorrow. The snow will be at its heaviest during the rush hour tomorrow morning, making for a very messy, slow, and dangerous commute. In fact, there could be some isolated instances of thundersnow tomorrow, if any convective bands of snow could form. In the heaviest bands of snow, snow could fall at a 1"/hour rate. Another 4-6" of snow will fall during the day tomorrow. After noontime tomorrow, the snow will gradually diminish in intensity, before stopping completely during the late afternoon hours tomorrow. However, I would expect that the roads would still be in poor shape for the evening commute tomorrow. By Tuesday Morning, the roads will probably be in better shape, as temperatures will be warm enough for road salt to be effective.
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Snow Day Prediction:
Monday: A good analog to this storm would be the 12/19/08 storm from last winter. Snow did not start falling until 5 a.m. in that storm, but it got very heavy very quickly, resulting in dangerous morning and evening commutes. Our school closed then, and I would expect it to close now. Despite only minor accumulations by rush hour tomorrow morning, moderate-heavy snow will be falling, making for a treacherous commute. In addition, 4-6 more inches of snow will fall during the day, which will not get cleared off of many roads. This would result in long bus delays on the ride home from school. Due to these factors, I am predicting that we will not have school tomorrow.
Tuesday: I would expect the storm to more or less end at around 5 p.m. tomorrow, giving the road crews around 12 hours to clear the roads. As I mentioned above, road salt will be effective in this situation, and it's not going to be an extremely large amount of snow to deal with. Therefore, I expect many of the roads to be cleared by Tuesday Morning, and will therefore lower the snow day grade for Tuesday to a "D" (small chance of a snow day, but not completely impossible).
All of the forecast models are in good agreement, so I will simply show the NAM and GFS, as they have the most detailed images.
NAM:
This image of the NAM shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the NAM shows a simulated radar image of the snow that will be affecting us tomorrow morning.
This image of the NAM shows storm total precipitation. This would give us around 7" of snow.
GFS:
This image of the GFS shows moderate-heavy snowfall affecting SE Michigan between 7 a.m. and 1 p.m. tomorrow.
This image of the GFS shows storm total precipitation. This would give us around 7" of snow.
-----
Snowfall Map:
The forecast models have been very consistent in showing the most precipitation falling in far SE Michigan. However, it now appears likely that the snow will mix with sleet in the early morning tomorrow near the Ohio Border. This will offset the higher precipitation amounts. In addition, there will be a lower snow-to-water ratio, which will also cut down on accumulations. Due to this, I will go with 5-7" for areas near the Ohio Border.
The most snow will likely fall between the I-94 and I-69 corridors. Here, lots of precipitation will still fall, but the snow will not mix with sleet tomorrow morning. Due to this, I will go with 6-8" for this area.
To the north of the I-69 corridor, precipitation amounts will start to taper off. Due to this, I will go with 5-7", and in the far northern counties, 4-6".
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Impacts From This Storm:
As you can see from the above radar image, this storm is on our doorstep. Snow will begin falling around midnight tonight, and increase in intensity as the night goes on. I would expect around 2" of snow to be on the ground by 6 a.m. tomorrow. The snow will be at its heaviest during the rush hour tomorrow morning, making for a very messy, slow, and dangerous commute. In fact, there could be some isolated instances of thundersnow tomorrow, if any convective bands of snow could form. In the heaviest bands of snow, snow could fall at a 1"/hour rate. Another 4-6" of snow will fall during the day tomorrow. After noontime tomorrow, the snow will gradually diminish in intensity, before stopping completely during the late afternoon hours tomorrow. However, I would expect that the roads would still be in poor shape for the evening commute tomorrow. By Tuesday Morning, the roads will probably be in better shape, as temperatures will be warm enough for road salt to be effective.
-----
Snow Day Prediction:
Monday: A good analog to this storm would be the 12/19/08 storm from last winter. Snow did not start falling until 5 a.m. in that storm, but it got very heavy very quickly, resulting in dangerous morning and evening commutes. Our school closed then, and I would expect it to close now. Despite only minor accumulations by rush hour tomorrow morning, moderate-heavy snow will be falling, making for a treacherous commute. In addition, 4-6 more inches of snow will fall during the day, which will not get cleared off of many roads. This would result in long bus delays on the ride home from school. Due to these factors, I am predicting that we will not have school tomorrow.
Tuesday: I would expect the storm to more or less end at around 5 p.m. tomorrow, giving the road crews around 12 hours to clear the roads. As I mentioned above, road salt will be effective in this situation, and it's not going to be an extremely large amount of snow to deal with. Therefore, I expect many of the roads to be cleared by Tuesday Morning, and will therefore lower the snow day grade for Tuesday to a "D" (small chance of a snow day, but not completely impossible).
Saturday, February 20, 2010
Snow Day Likely Monday, Possibly Another One Tuesday
I am glad to say that we now have a good amount of consistency with the models for the storm that will affect us during the entire day on Monday. It is looking good for 5-9" of snow to fall on Monday, with a good chance of a snow day on Monday & another chance for a snow day on Tuesday.
Let's look at some forecast models...
12z NAM looks good for a general 5-9" of snow across SE Michigan, with no precipitation type issues.
12z GFS, similar to the NAM.
12z GGEM, similar to the NAM & GFS for precipitation amounts but we could have a mixing issue as temperatures get above freezing for a bit.
12z ECMWF still has a general 5-9" of snow across SE Michigan, but the heaviest falls to the west.
Considering all this, I am going to make the most boring snowfall map ever. When taking into consideration all of the 12z models, it appears that a little more precipitation may fall in the far SE part of the state, but that they may have a little bit of an issue with the snow turning into sleet in the middle of the event. I will split the difference and just paint a general 5-9" of snow across the entire forecast area.
Currently, the timeframe of the storm is speeding up. I would now expect snow to begin falling at around 2 a.m. Monday Morning, with the heaviest snow falling during the day on Monday, before ending late Monday Evening. Considering this, I think a snow day now looks likely on Monday, and as such, I will raise the snow day grade to a "B" (snow day likely, but not a lock yet). Depending on how much snow falls and how quickly the storm ends, I could see another snow day occuring on Tuesday. However, there is a large difference between a 5" snowstorm that ends late Monday Evening, and a 9" snowstorm that ends late Monday Evening. Due to this, I will keep the snow day grade for Tuesday at a "C" (50/50, could break either way). If we end up getting in the upper range of my accumulation prediction, I could definitely see us getting 2 snow days.
Either way, a snow day looks likely Monday, as moderate/heavy snow will likely be falling by the time we have to go to school. Then, 3-6" of snow will probably be on the ground by the time school gets out Monday Afternoon, making the commute home a nightmare either way. Based on past trends, there is no reason to believe our school will be hesitant to call a snow day on Monday simply because there won't be a lot of snow on the ground by Monday Morning.
Bottom Line: 5-9" of snow, snow day likely Monday, snow day possible Tuesday.
Let's look at some forecast models...
12z NAM looks good for a general 5-9" of snow across SE Michigan, with no precipitation type issues.
12z GFS, similar to the NAM.
12z GGEM, similar to the NAM & GFS for precipitation amounts but we could have a mixing issue as temperatures get above freezing for a bit.
12z ECMWF still has a general 5-9" of snow across SE Michigan, but the heaviest falls to the west.
Considering all this, I am going to make the most boring snowfall map ever. When taking into consideration all of the 12z models, it appears that a little more precipitation may fall in the far SE part of the state, but that they may have a little bit of an issue with the snow turning into sleet in the middle of the event. I will split the difference and just paint a general 5-9" of snow across the entire forecast area.
Currently, the timeframe of the storm is speeding up. I would now expect snow to begin falling at around 2 a.m. Monday Morning, with the heaviest snow falling during the day on Monday, before ending late Monday Evening. Considering this, I think a snow day now looks likely on Monday, and as such, I will raise the snow day grade to a "B" (snow day likely, but not a lock yet). Depending on how much snow falls and how quickly the storm ends, I could see another snow day occuring on Tuesday. However, there is a large difference between a 5" snowstorm that ends late Monday Evening, and a 9" snowstorm that ends late Monday Evening. Due to this, I will keep the snow day grade for Tuesday at a "C" (50/50, could break either way). If we end up getting in the upper range of my accumulation prediction, I could definitely see us getting 2 snow days.
Either way, a snow day looks likely Monday, as moderate/heavy snow will likely be falling by the time we have to go to school. Then, 3-6" of snow will probably be on the ground by the time school gets out Monday Afternoon, making the commute home a nightmare either way. Based on past trends, there is no reason to believe our school will be hesitant to call a snow day on Monday simply because there won't be a lot of snow on the ground by Monday Morning.
Bottom Line: 5-9" of snow, snow day likely Monday, snow day possible Tuesday.
Good model agreement for the storm
It's late, and I'm too tired to post images, so I'll save that for tomorrow afternoon's post, but I will say that we have good model agreement for this storm now.
The NAM, GFS, GGEM, and ECMWF models all give us significant precipitation with this storm. Even the lesser models are in decent agreement with this now. So, at this time, I would say that there is no chance that this storm will miss us to the south. The main thing I think we would have to worry about this point is for some ice, sleet, or rain to mix in with the snow, but so far, only the GGEM has shown the potential for this to happen.
However, all in all, I have a pretty high confidence in a Winter Storm Warning event for our area. To stay on the safe side for now (due to potential issues such as dry slotting or mixing), I will call for 5-9" of snow with this storm. However, if we do not have precipitation type issues, accumulations will likely have to be adjusted upwards.
The bottom line is that barring another major shift to the northwest in the storm track, I would expect at least 5" of snow with this storm, and in all likelihood, I would think more than that would fall.
With regards to snow day chances, it's kind of unclear at this point. This will likely be a long duration snowstorm (18-24 hours) so I believe it is likely that we will get at least one snow day with this storm. Earlier today, I stated it was more likely that we would get Tuesday off with this storm, if we got a snow day. However, the starting time for this storm has sped up. The storm is now expected to start early Monday Morning, and finish late Monday Evening. With this timing, I am really kind of unsure as to which day we would be more likely to get a snow day.
For now, to split the difference, I will make the snow day grade for both Monday and Tuesday a "C", but I do believe that if everything stays the same with this storm, we will get at least one snow day, with an outside shot at two.
Again, it should be a fun few days tracking this storm. The next post will be up sometime tomorrow afternoon...
The NAM, GFS, GGEM, and ECMWF models all give us significant precipitation with this storm. Even the lesser models are in decent agreement with this now. So, at this time, I would say that there is no chance that this storm will miss us to the south. The main thing I think we would have to worry about this point is for some ice, sleet, or rain to mix in with the snow, but so far, only the GGEM has shown the potential for this to happen.
However, all in all, I have a pretty high confidence in a Winter Storm Warning event for our area. To stay on the safe side for now (due to potential issues such as dry slotting or mixing), I will call for 5-9" of snow with this storm. However, if we do not have precipitation type issues, accumulations will likely have to be adjusted upwards.
The bottom line is that barring another major shift to the northwest in the storm track, I would expect at least 5" of snow with this storm, and in all likelihood, I would think more than that would fall.
With regards to snow day chances, it's kind of unclear at this point. This will likely be a long duration snowstorm (18-24 hours) so I believe it is likely that we will get at least one snow day with this storm. Earlier today, I stated it was more likely that we would get Tuesday off with this storm, if we got a snow day. However, the starting time for this storm has sped up. The storm is now expected to start early Monday Morning, and finish late Monday Evening. With this timing, I am really kind of unsure as to which day we would be more likely to get a snow day.
For now, to split the difference, I will make the snow day grade for both Monday and Tuesday a "C", but I do believe that if everything stays the same with this storm, we will get at least one snow day, with an outside shot at two.
Again, it should be a fun few days tracking this storm. The next post will be up sometime tomorrow afternoon...
Friday, February 19, 2010
Lookin' Goooood :)
I will post a full update by midnight tonight, but right now I'll just say that it's looking good for another nice snowstorm in SE Michigan. As of right now, it definitely seems like we're going to get affected by a storm, the main question is whether we will changeover to ice or rain rain at some point, which would obviously cut down on accumulations. Right now, it looks like that probably won't happen, and that accumulations of 5-9" look likely. If we can get into the heaviest bands, 10"+ is even possible. Obviously more will be known about this storm in the next couple of days, and I will have a lot more confidence in any one solution by tomorrow night. Tuesday looks decent for a snow day right now.
Thursday, February 18, 2010
Forecast Model Madness
To get an idea of the disagreement going on with this storm, take a look at the GFS (top image) versus the ECMWF (bottom image). The GFS is hundreds of miles south, and would result in nothing happening in SE Michigan, while the ECMWF's scenario has us getting a nice winter storm.
This disagreement likely will not be settled until this weekend...trust me when I say that I do not know what is going to happen with this storm yet. There's a chance for a storm, that's all I'll say for now.
Also FWIW I was busy tonight (Thursday Night) so no time for a new post. Basically, not much has changed, there is still large disagreement among the models. I'll have a longer post up by midnight tomorrow as long as there is still a chance that the storm will affect us.
This disagreement likely will not be settled until this weekend...trust me when I say that I do not know what is going to happen with this storm yet. There's a chance for a storm, that's all I'll say for now.
Also FWIW I was busy tonight (Thursday Night) so no time for a new post. Basically, not much has changed, there is still large disagreement among the models. I'll have a longer post up by midnight tomorrow as long as there is still a chance that the storm will affect us.
Wednesday, February 17, 2010
Next
Seems like there is a possibility for another storm around Monday...unlike the last storm, I am far from confident that this one will affect us, but it's still worth blogging about, so I'll look into it a little more tonight.
Tuesday, February 9, 2010
1st Snow Day of the Year :)
Obviously very satisfied with my forecasting leading up to this storm as I started mentioning this one as early as Friday, and gave it an above average snowfall grade as early as Saturday.
Otherwise, this will be my final update...radar still shows a swath of precipitation over SE Michigan, and we already have nearly 5" of snow, I have no fear that we reach 7" with this storm.
Tomorrow I may edit this with a map comparing actual totals to my forecasted totals.
Otherwise, this will be my final update...radar still shows a swath of precipitation over SE Michigan, and we already have nearly 5" of snow, I have no fear that we reach 7" with this storm.
Tomorrow I may edit this with a map comparing actual totals to my forecasted totals.
Update #2
Heaviest bands yet are about to move through here...in the next 6 hours I would think 4-5" fall...storm total of 7-9" seems pretty good to predict.
Update #1
Already almost 3" here at my house, and with hours of moderate/heavy snow coming up, don't see any way we end up with less than 7"...check out the radar below.
Obviously minimum of 7" is well more than enough for a snow day...it's now not a matter of if, but when, they call school. Looks like my forecast of 6-10" will verify quite well...and I still see some isolated jackpot totals over 1' south of us.
Obviously minimum of 7" is well more than enough for a snow day...it's now not a matter of if, but when, they call school. Looks like my forecast of 6-10" will verify quite well...and I still see some isolated jackpot totals over 1' south of us.
Final Snow Map and Prediction
I still like my map from last night, only change I will make is to increase high end accumulations between Bay City and I-69 from 7" to 8". This is because (a) forecast models last night came in a little wetter for some of that area (b) lake enhancement from Lake Huron could increase totals by 1-2" in the lakeshore counties from what they would otherwise be. Therefore I feel it's prudent to put in an area of 4-8". Other than that, everything seems to be on track with the storm. The National Weather Service moved an inch closer to my predictions, but one of us still has to be wrong, especially south of Detroit where they have 5-9" and I have 8-12". We'll see, I still think they're lowballing totals a little bit.
Here's my final map:
In addition, there's no point in waiting until tonight...so I'll just predict right now that we will get a snow day tomorrow. I can't possibly see how we wouldn't, even if the lower totals forecasted by the National Weather Service are correct.
I'll have one or two new posts up tonight, first one probably between 6:00 and 7:00 p.m.
Here's my final map:
In addition, there's no point in waiting until tonight...so I'll just predict right now that we will get a snow day tomorrow. I can't possibly see how we wouldn't, even if the lower totals forecasted by the National Weather Service are correct.
I'll have one or two new posts up tonight, first one probably between 6:00 and 7:00 p.m.
Monday, February 8, 2010
Yes, I am forecasting much higher than the NWS...hear me out
Needless to say, I was really surprised when I saw that the National Weather Service dropped our forecasted accumulations to 4-7"...and to be honest, I can't really find a good reason why they're doing that. I can agree with them that there will be some dry air to overcome at the onset of the storm, but since the heaviest snow is going to fall around 12 hours after the storm begins, I don't think the dry air will cut into accumulations much at all. They see a south trend with the precipitation shown by the forecast models, but I haven't seen any model move far enough south to knock us out of the 6-10" range. There has been a slight southward trend in the models over the last day or so, and seasonal trends support the storm moving a little further north than is currently depicted by the models (this last minute northward trend has happened to every storm this year that I can remember). Therefore, I'm really questioning why the National Weather Service dropped our totals, especially when the National Weather Service in Grand Rapids forecasts 6-10" to fall in the counties to the west of us, and 8-12" to fall in the counties to the southwest of us. I think that is a more realistic depiction of what will actually happen.
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Forecast Model Images:
NAM
This image of the NAM shows a heavy band of snow impacting the M-59 and I-94 corridors early Wednesday Morning:
This image of the NAM shows that band of snow affecting us in simulated radar form:
This image of the NAM shows storm total precipitation. It has moved south from yesterday, but if you read my discussion yesterday, you'll note that I was disregarding the NAM in the first place because it was too far north. It is simply moving into model consensus...
GFS
This image of the GFS shows moderate-to-heavy snowfall impacting all of SE Michigan early Wednesday morning. Note the tightly packed pressure gradient, which will result in very windy conditions which will blow the snow around, with the end result being huge snow drifts.
This image of the GFS shows storm total precipitation...note how similar it is to the NAM...
GGEM
This image of the GGEM shows moderate-to-heavy snowfall impacting all of SE Michgian early Wednesday morning.
This image of the GGEM show storm total precipitation...a bit drier than the NAM & GFS, but still has the dark blue over us, which equates to 6" minimum
ECMWF
Once again, no pics, but apparently it also is a bit drier than the NAM & GFS...still showing at least 6" of snow for us...
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Forecast Model Preference:
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Forecast Model Images:
NAM
This image of the NAM shows a heavy band of snow impacting the M-59 and I-94 corridors early Wednesday Morning:
This image of the NAM shows that band of snow affecting us in simulated radar form:
This image of the NAM shows storm total precipitation. It has moved south from yesterday, but if you read my discussion yesterday, you'll note that I was disregarding the NAM in the first place because it was too far north. It is simply moving into model consensus...
GFS
This image of the GFS shows moderate-to-heavy snowfall impacting all of SE Michigan early Wednesday morning. Note the tightly packed pressure gradient, which will result in very windy conditions which will blow the snow around, with the end result being huge snow drifts.
This image of the GFS shows storm total precipitation...note how similar it is to the NAM...
GGEM
This image of the GGEM shows moderate-to-heavy snowfall impacting all of SE Michgian early Wednesday morning.
This image of the GGEM show storm total precipitation...a bit drier than the NAM & GFS, but still has the dark blue over us, which equates to 6" minimum
ECMWF
Once again, no pics, but apparently it also is a bit drier than the NAM & GFS...still showing at least 6" of snow for us...
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Forecast Model Preference:
All models show a near-perfect storm track for SE Michigan to get heavy snows, there has been almost no change since yesterday. Models have basically stayed the same with precipitation (except for the NAM which went south to the model consensus). There is now a tight model consensus for where the heaviest precipitation will occur, which is south of I-696 and into NW Ohio. I have no preference on the track, for precipitation, I will use a blend of all four of the major models. Really, it's getting to the point in the storm where models become almost useless, and by tomorrow, we'll be nowcasting...
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Snow Map:
Once again, I am glad I used 15:1 snow-to-water ratios (for a further discussion on ratios, look at the discussions below), as it looks like these may not even be met. I always like to stay conservative on ratios, so for this map, I will stick to 13:1 ratios.
For Detroit south, I will assume they will get anywhere from 0.65-0.95" of water equivalent. With 13:1 ratios, this equates to anywhere from 8.45-12.35" of snow. I'll just round those down, for a forecast of 8-12". I still feel some areas with persistent heavier banding could get over a foot, so I will include the "Locally Higher" label.
From I-69 to Detroit, I will assume we get anywhere from 0.5-0.75" of water equivalent. With 13:1 ratios, this equates to anywhere from 6.5-9.75" of snow. To give myself some breathing room, I'll round the 6.5" down and the 9.75" up, for a forecast of 6-10". Come tomorrow morning, when I make my final prediction, I may shave an inch of the bottom or the top of the forecast, depending on nowcasting trends...
From I-69 up to Bay City, I will assume they will get anywhere from 0.3-0.5" of water equivalent. With 13:1 ratios, this equates to anywhere from 3.9-6.5" of snow. I'll round the 3.9" up to 4", and round the 6.5" up to 7" as I have a hard time believing amounts will diminish extremely quickly.
North of Bay City, I'll cut amounts just a little bit more due to the slight south trend, for 3-6". Due to enhancement from Lake Huron, I will not cut amounts in the Thumb, opting to keep them at 4-7".
This is reflected in the following snow map:
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Snow Day Chances:
My thinking still hasn't changed. It's early February, and we haven't had a snow day. Therefore, I feel anywhere from 5" on up gets us a snow day. In fact, due to the blowing and drifting of snow, 4" may do the trick. However, I still find the National Weather Service's forecast quite curious, and am still quite confident we end up with 6+" of snow.
Snow will start around noon tomorrow. This event will start slowly, but will pick up steam rapidly in the evening, with moderate-to-heavy snow falling after 8 p.m. tomorrow night and continuing on into the morning hours on Wednesday. Rush hour traffic will be severely impacted, as the road comission simply will not be able to keep up with the snow. Adding to the headache will be 20-30 mph winds that will cause near-whiteout conditions at times, and cause snow drifts up to 2' high, rendering some back roads nearly impassable. In fact, some weather outlets have hinted at gusts up to 40 mph as the storm departs. Considering all this, there is almost no doubt in my mind that we will have a snow day Wednesday. I have no reason not to raise the snow day grade to an "A" (near 100% chance of a snow day) for the first time this year. Everything looks set for our first snow day to occur on Wednesday. Hope everyone enjoys the storm.
Sunday, February 7, 2010
Tuesday/Wednesday Storm = Love
Another couple of model runs, and even more confidence that the storm that occurs Tuesday/Wednesday is going to be "the one" for the winter of 2009-10, at least so far. If you want to know what in the atmosphere is causing this storm to occur, scroll down to the last few posts...today I'm going to focus on what the different models are showing. Then, I'll use the current model guidance to make a preliminary snowfall map and state my thoughts on the chances of a snow day.
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Forecast Model Images:
NAM
This image of the NAM shows a very heavy band of snow affecting anyone from M-59 north in SE Michigan from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the NAM shows that band affecting us in simulated radar form, just another look at the band of snow:
Finally, this image of the NAM shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the M-59 and I-69 corridors:
GFS
This image of the GFS shows moderate-to-heavy snow affecting everyone in NW Ohio and SE Michigan. Note the tighly packed black lines. This represents a strong pressure gradient and the likely result would be near blizzard or even low end blizzard conditions from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the GFS shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the I-94 corridor down to NW Ohio:
GGEM
This image of the GGEM shows a band of heavy snow impact NW Ohio. Moderate snow is still falling in SE Michigan:
This image of the GGEM shows storm total snowfall. It paints the highest accumulations (likely 11-17") over NW Ohio:
ECMWF
No pictures with the ECMWF due to its horrible resolution, but it is similar to the GFS in its precipitation output.
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Forecast Model Preference:
The forecast models are tightly clustered with regards to track, generally tracking a low up Western Ohio passing just east of or over Detroit, before the energy transfers to a secondary low on the east coast. Due to the high confidence in the track, I will take the "middle of the road" models when it comes to precipitation. This means disregarding the further north NAM and further south GGEM as outliers when it comes to precipitation, and relying on the ECMWF and GFS.
Therefore, for my snow map, I will assume that the highest precipitation totals will be from the I-94 corridor south, with precipitation amounts gradually tapering off as you head to the north.
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Snow Map:
With my snow map, I will assume a general 15:1 snow-to-water ratio, just to be on the safe side. Ratios could definitely be higher, but ratios have fallen short of what has been expected too often for me to feel comfortable using anything higher than 15:1.
For Detroit south, I will assume they will get anywhere from 0.75 - 1.0" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 11.25-15" of snow. Due to the possibility that higher precipitation amounts could shift, I will give them a low end accumulation of 8". I also see any accumulations of over 14" being highly localized. They could happen, but to keep it safe 60 hours out, I will forecast 8-14" with a "Locally Higher" label from I-94 south.
Between Saginaw and Detroit, I will assume we will get anywhere from 0.5-0.7" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 7.5-10.5" of snow. Once again, due to the possibility that higher precipitation amounts could shift, I will give us a low end accumulation of 6". Considering it's still 60 hours out, I will round down the 10.5" to a high end of 10" of accumulation. Therefore, my forecast for this area will be 6-10" of snow.
North of Saginaw, I will assume they will get anywhere from 0.3-0.5" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 4.5-7.5" of snow. North of Saginaw, any shift to the north or south could have a fairly significant effect on accumulations. Therefore I'll round the low end down and the high end up for a forecast of 4-8" of snow.
This is reflected in the following snow map:
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Snow Day Chances:
The timeframe of this storm has moved back even a little further. Snow is now expected to start Tuesday Afternoon, continuing through Wednesday Afternoon, with the heaviest snow falling early Wednesday Morning. Obviously, this is pretty much perfect timing for a snow day, and if precipitation ends late enough on Wednesday, we could get two...but for now I will only talk about the snow day chances on Wednesday.
Considering it's early February, and we haven't had a snow day yet, I think anywhere from 5"+ could get us a snow day. Obviously, the low end of my snowfall forecast is for 6" of snow, so the amount of snow should also suffice.
Finally, one more thing in our favor is that at the height of the storm, near blizzard conditions are likely. I could easily see winds gusting up to 30-35 mph with a tight air pressure gradient over our region. This will result in whiteout conditions, and extensive blowing and drifting of snow. I would expect some drifts to be over 2'.
Obviously, the road commission is not going to be able to keep up with this mess. The only reason I won't move the snow day grade to an "A" is that we're still over 2 days out, but if everything looks the same at this time tomorrow, I will move it to an "A". For now though, I'll keep it at a "B" (good chance of a snow day, but not a lock yet). This is pretty much as confident as I'll ever be for a storm that's still 2 days away. I'd expect the National Weather Service to have Winter Storm Watches up either this afternoon or tomorrow morning. Should be a fun next few days tracking this one...
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Forecast Model Images:
NAM
This image of the NAM shows a very heavy band of snow affecting anyone from M-59 north in SE Michigan from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the NAM shows that band affecting us in simulated radar form, just another look at the band of snow:
Finally, this image of the NAM shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the M-59 and I-69 corridors:
GFS
This image of the GFS shows moderate-to-heavy snow affecting everyone in NW Ohio and SE Michigan. Note the tighly packed black lines. This represents a strong pressure gradient and the likely result would be near blizzard or even low end blizzard conditions from 1 a.m. - 7 a.m. Wednesday Morning:
This image of the GFS shows storm total snowfall. It paints the highest accumulations (likely 10-15") over the I-94 corridor down to NW Ohio:
GGEM
This image of the GGEM shows a band of heavy snow impact NW Ohio. Moderate snow is still falling in SE Michigan:
This image of the GGEM shows storm total snowfall. It paints the highest accumulations (likely 11-17") over NW Ohio:
ECMWF
No pictures with the ECMWF due to its horrible resolution, but it is similar to the GFS in its precipitation output.
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Forecast Model Preference:
The forecast models are tightly clustered with regards to track, generally tracking a low up Western Ohio passing just east of or over Detroit, before the energy transfers to a secondary low on the east coast. Due to the high confidence in the track, I will take the "middle of the road" models when it comes to precipitation. This means disregarding the further north NAM and further south GGEM as outliers when it comes to precipitation, and relying on the ECMWF and GFS.
Therefore, for my snow map, I will assume that the highest precipitation totals will be from the I-94 corridor south, with precipitation amounts gradually tapering off as you head to the north.
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Snow Map:
With my snow map, I will assume a general 15:1 snow-to-water ratio, just to be on the safe side. Ratios could definitely be higher, but ratios have fallen short of what has been expected too often for me to feel comfortable using anything higher than 15:1.
For Detroit south, I will assume they will get anywhere from 0.75 - 1.0" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 11.25-15" of snow. Due to the possibility that higher precipitation amounts could shift, I will give them a low end accumulation of 8". I also see any accumulations of over 14" being highly localized. They could happen, but to keep it safe 60 hours out, I will forecast 8-14" with a "Locally Higher" label from I-94 south.
Between Saginaw and Detroit, I will assume we will get anywhere from 0.5-0.7" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 7.5-10.5" of snow. Once again, due to the possibility that higher precipitation amounts could shift, I will give us a low end accumulation of 6". Considering it's still 60 hours out, I will round down the 10.5" to a high end of 10" of accumulation. Therefore, my forecast for this area will be 6-10" of snow.
North of Saginaw, I will assume they will get anywhere from 0.3-0.5" of water equivalent. With a 15:1 ratio, this is equivalent to anywhere from 4.5-7.5" of snow. North of Saginaw, any shift to the north or south could have a fairly significant effect on accumulations. Therefore I'll round the low end down and the high end up for a forecast of 4-8" of snow.
This is reflected in the following snow map:
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Snow Day Chances:
The timeframe of this storm has moved back even a little further. Snow is now expected to start Tuesday Afternoon, continuing through Wednesday Afternoon, with the heaviest snow falling early Wednesday Morning. Obviously, this is pretty much perfect timing for a snow day, and if precipitation ends late enough on Wednesday, we could get two...but for now I will only talk about the snow day chances on Wednesday.
Considering it's early February, and we haven't had a snow day yet, I think anywhere from 5"+ could get us a snow day. Obviously, the low end of my snowfall forecast is for 6" of snow, so the amount of snow should also suffice.
Finally, one more thing in our favor is that at the height of the storm, near blizzard conditions are likely. I could easily see winds gusting up to 30-35 mph with a tight air pressure gradient over our region. This will result in whiteout conditions, and extensive blowing and drifting of snow. I would expect some drifts to be over 2'.
Obviously, the road commission is not going to be able to keep up with this mess. The only reason I won't move the snow day grade to an "A" is that we're still over 2 days out, but if everything looks the same at this time tomorrow, I will move it to an "A". For now though, I'll keep it at a "B" (good chance of a snow day, but not a lock yet). This is pretty much as confident as I'll ever be for a storm that's still 2 days away. I'd expect the National Weather Service to have Winter Storm Watches up either this afternoon or tomorrow morning. Should be a fun next few days tracking this one...
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