Blame the low going north of what was forecasted and blame the dry air for causing what was supposed to be an awesome first band to dissipate, but the bottom line is that this storm will be yet another bust, with Lake Orion probably picking up 3-4" when all is said and done.
Someone will get 6-10" from this...unforunately, that someone is northern Michigan.
P.S. - I'm just about done with winter if all we're going to get is busts.
Saturday, February 21, 2009
Friday, February 20, 2009
Final Snow Map
The forecast models have trended the low pressure track even further north since yesterday, meaning less snow for us as snow ratios become lower (12:1 or so) and we get hit by a big time dry slot. Still expecting 5-7" of snow over 6 hours or so tomorrow. Not expecting a snow day ATTM though.
Thursday, February 19, 2009
Enhanced Alberta Clipper will dump snow on Southeast Michigan this weekend.
A low pressure system will drop out of Alberta tomorrow, then dive down to around St. Louis by tomorrow night. From there I expect this low pressure system to track approximately from St. Louis to Normal, Illinois to Toledo, Ohio and then off to the northeast into Canada. This low pressure system will likely produce a nice snowstorm for Southeast Michigan this weekend.
Now, Alberta Clippers usually give us only "nuisiance snowfalls" of around 3-6". Earlier this week, that was what this clipper was supposed to do, as it was originally forecasted to track well to our south (from Lincoln, Illinois to Indianapolis to Columbus). However, forecast models have moved the track to the north in the last day or so, and are now in strong agreement on a track similar to the one I mentioned in the first paragraph. This track will allow Southeast Michigan to get in on the main snow shield, and therefore get the highest accumulations out of this system. And since this is a stronger than normal Alberta Clipper, snow totals will be higher than the normal 3-6" expected from Alberta Clippers.
How high will snow totals be? Here's my snowfall map:
My accumulations are on the high end of the forecasts of professional meteorologists, and here's why:
First of all, some definitions will be necessary...
The GFS and the NAM are the two forecast models which I use to figure out approximately how much precipitation we will receive from a particular system.
QPF is an acronym for "Quantitative Precipitation Forecast". It's basically a fancy way of saying how much liquid precipitation will fall in a particular area based on forecast model guidance.
Finally, snow ratios are how many inches of snow you could receive from one inch of rain. For example, a 10:1 snow ratio (a normal snow ratio at 32 degrees) means that for every inch of rain that falls, you would get 10 inches of snow. Since we will have temperatures in the mid 20's on Saturday, we will get higher snow ratios (around 15:1 to 18:1). Multiply the QPF and the expected snow ratios to get the expected snowfall.
So, here goes nothing:
A blend of GFS and NAM QPF totals generally supports 0.30-0.55” of QPF falling in SE Michigan with this system, with the higher QPF over the southern portion of the forecast area, closer to the low pressure system. Assume 0.45-0.55” of QPF over the southern half of the forecast area, with snow ratios between 15:1 and 18:1. 0.45*15 = 6” of snow (lower limit) and 0.55*18 = 9.9” of snow (upper limit). Therefore, I have forecasted a general 6-10” of accumulation over the southern half of the forecast area. Then, assume 0.30-0.45” of QPF over the northern half of the forecast area, with snow ratios between 18:1 and 20:1. 0.30*18 = 5.4” of snow, and 0.45*20 = 9” of snow. However, I have bumped down accumulations about an inch for the northern half of the forecast area because clippers tend to have fairly sharp accumulation cutoffs.
I have also included a "locally 12 inches" mention over the southern half of the forecast area because a heavier band of snow (called a deformation band) will set up somewhere to the north of the low pressure system. Areas in this band will likely receive a foot of snow. The favored area for this band of snow will probably be somewhere between I-69 and I-94 (that's right, our area!).
So, what does this all mean for snow days? This would be a lock if this storm was occurring during the week, but unfortunately for us, the brunt of the snow will fall on Saturday. I would expect the snow to start Saturday morning, with the heaviest snow falling between noon and 4 p.m. Saturday afternoon. All snow will taper off by early Sunday Morning. However, all hope is not lost. First of all, you can't discount the fact that we have a road commission that is slow at best at clearing the roads. So, some back roads may still not be cleared off by Monday morning, which could result in a snow day.
Another nice possibility is that some model runs have shown that this system could stall out a little bit on Sunday morning because of a high pressure system in the Atlantic Ocean. If this happen, we could end up with even higher snow totals than currently expected and snowfall ending later than expected (late Sunday morning), which would likely mean a snow day for us on Monday. This could possibly be the reason why the National Weather Service in Detroit has bumped our forecasted snow totals up from 6-9" this afternoon to 7-13" currently.
All in all, this is an extremely promising storm system, and our best hope for a snow day in a while, despite the horrible timing.
Now, Alberta Clippers usually give us only "nuisiance snowfalls" of around 3-6". Earlier this week, that was what this clipper was supposed to do, as it was originally forecasted to track well to our south (from Lincoln, Illinois to Indianapolis to Columbus). However, forecast models have moved the track to the north in the last day or so, and are now in strong agreement on a track similar to the one I mentioned in the first paragraph. This track will allow Southeast Michigan to get in on the main snow shield, and therefore get the highest accumulations out of this system. And since this is a stronger than normal Alberta Clipper, snow totals will be higher than the normal 3-6" expected from Alberta Clippers.
How high will snow totals be? Here's my snowfall map:
My accumulations are on the high end of the forecasts of professional meteorologists, and here's why:
First of all, some definitions will be necessary...
The GFS and the NAM are the two forecast models which I use to figure out approximately how much precipitation we will receive from a particular system.
QPF is an acronym for "Quantitative Precipitation Forecast". It's basically a fancy way of saying how much liquid precipitation will fall in a particular area based on forecast model guidance.
Finally, snow ratios are how many inches of snow you could receive from one inch of rain. For example, a 10:1 snow ratio (a normal snow ratio at 32 degrees) means that for every inch of rain that falls, you would get 10 inches of snow. Since we will have temperatures in the mid 20's on Saturday, we will get higher snow ratios (around 15:1 to 18:1). Multiply the QPF and the expected snow ratios to get the expected snowfall.
So, here goes nothing:
A blend of GFS and NAM QPF totals generally supports 0.30-0.55” of QPF falling in SE Michigan with this system, with the higher QPF over the southern portion of the forecast area, closer to the low pressure system. Assume 0.45-0.55” of QPF over the southern half of the forecast area, with snow ratios between 15:1 and 18:1. 0.45*15 = 6” of snow (lower limit) and 0.55*18 = 9.9” of snow (upper limit). Therefore, I have forecasted a general 6-10” of accumulation over the southern half of the forecast area. Then, assume 0.30-0.45” of QPF over the northern half of the forecast area, with snow ratios between 18:1 and 20:1. 0.30*18 = 5.4” of snow, and 0.45*20 = 9” of snow. However, I have bumped down accumulations about an inch for the northern half of the forecast area because clippers tend to have fairly sharp accumulation cutoffs.
I have also included a "locally 12 inches" mention over the southern half of the forecast area because a heavier band of snow (called a deformation band) will set up somewhere to the north of the low pressure system. Areas in this band will likely receive a foot of snow. The favored area for this band of snow will probably be somewhere between I-69 and I-94 (that's right, our area!).
So, what does this all mean for snow days? This would be a lock if this storm was occurring during the week, but unfortunately for us, the brunt of the snow will fall on Saturday. I would expect the snow to start Saturday morning, with the heaviest snow falling between noon and 4 p.m. Saturday afternoon. All snow will taper off by early Sunday Morning. However, all hope is not lost. First of all, you can't discount the fact that we have a road commission that is slow at best at clearing the roads. So, some back roads may still not be cleared off by Monday morning, which could result in a snow day.
Another nice possibility is that some model runs have shown that this system could stall out a little bit on Sunday morning because of a high pressure system in the Atlantic Ocean. If this happen, we could end up with even higher snow totals than currently expected and snowfall ending later than expected (late Sunday morning), which would likely mean a snow day for us on Monday. This could possibly be the reason why the National Weather Service in Detroit has bumped our forecasted snow totals up from 6-9" this afternoon to 7-13" currently.
All in all, this is an extremely promising storm system, and our best hope for a snow day in a while, despite the horrible timing.
Wednesday, February 18, 2009
Obviously
Obviously, the heavy precipitation that fell today fell as rain, due to it being warmer than expected. Combine that with the fact that we only got about half an inch of snow this morning, and it's obvious that this storm was a bust, even if we get the upper end of the 1-3" expected by tomorrow afternoon.
Chances are, we'll have a favorable storm track and cold enough temperatures for some decent snow on Saturday. But that obviously won't help us too much as far as snow days go.
Beyond that, it is definitely possible that we won't have any more major snowstorms, as the weather looks to warm up towards the end of February and early March. The end of winter may soon be in sight.
Chances are, we'll have a favorable storm track and cold enough temperatures for some decent snow on Saturday. But that obviously won't help us too much as far as snow days go.
Beyond that, it is definitely possible that we won't have any more major snowstorms, as the weather looks to warm up towards the end of February and early March. The end of winter may soon be in sight.
Tuesday, February 17, 2009
Two Possibilities
There appear to be two possibilities of what could result from the complex storm system that will affect us from tomorrow morning until Thursday morning.
First of all, let's run down what is set in stone.
Firstly, a nice burst of snow should occur very early tomorrow morning, perhaps stretching into rush hour tomorrow. This burst of snow will likely produce 1-3" accumulations.
Then, a dry slot will cause this precipitation to cease. This is a good thing though, as temperatures will warm up above freezing during the day tomorrow.
A final round of snow will occur tomorrow night through Thursday morning, producing another 1-3" of snow.
One possibility has this as the only precipitation, with 2-6" of snow accumulating.
However, some forecast models show a nice, heavy band of precipitation could set up tomorrow afternoon. Wherever this band sets up, precipitation would likely fall as all snow despite surface temperatures being above freezing. The snow would likely fall hard enough to accumulate on the ground despite temperatures being above freezing. Despite low snow-to-water ratios, snowfall rates could easily reach 2" per hour where this band sets up. Accumulations of 3-5" are definitely possible wherever this band sets up, if it sets up. Therefore, if the band sets up over us, accumulations would have to be bumped up to 5-11".
My gut feel tells me that a band of snow will set up tomorrow, and we'll be in it somewhere. This seems like too dynamic of a storm for a band not to set up, and we seem to be in a decent spot to feel the effects of the band if it sets up.
Either way, we're not getting a snow day tomorrow from this storm. If the band sets up over us, we could get a snow day Thursday, but if the band doesn't set up over us or doesn't form at all, we almost certainly wouldn't get a snow day on Thursday.
First of all, let's run down what is set in stone.
Firstly, a nice burst of snow should occur very early tomorrow morning, perhaps stretching into rush hour tomorrow. This burst of snow will likely produce 1-3" accumulations.
Then, a dry slot will cause this precipitation to cease. This is a good thing though, as temperatures will warm up above freezing during the day tomorrow.
A final round of snow will occur tomorrow night through Thursday morning, producing another 1-3" of snow.
One possibility has this as the only precipitation, with 2-6" of snow accumulating.
However, some forecast models show a nice, heavy band of precipitation could set up tomorrow afternoon. Wherever this band sets up, precipitation would likely fall as all snow despite surface temperatures being above freezing. The snow would likely fall hard enough to accumulate on the ground despite temperatures being above freezing. Despite low snow-to-water ratios, snowfall rates could easily reach 2" per hour where this band sets up. Accumulations of 3-5" are definitely possible wherever this band sets up, if it sets up. Therefore, if the band sets up over us, accumulations would have to be bumped up to 5-11".
My gut feel tells me that a band of snow will set up tomorrow, and we'll be in it somewhere. This seems like too dynamic of a storm for a band not to set up, and we seem to be in a decent spot to feel the effects of the band if it sets up.
Either way, we're not getting a snow day tomorrow from this storm. If the band sets up over us, we could get a snow day Thursday, but if the band doesn't set up over us or doesn't form at all, we almost certainly wouldn't get a snow day on Thursday.
Monday, February 16, 2009
Update...
The general effects of this storm are still expected to be similar to what they were yesterday. The storm track has moved a little further south from yesterday; it is now expected to track from just south of Chicago to Detroit. However, temperatures are still expected to warm up enough for a changeover to rain on Wednesday.
The burst of heavy snow is still expected to occur out ahead of this storm, with anywhere between 2-6" of snow accumulating depending on how early this first wave of snow gets going. Once it starts to get going, snowfall rates of 1-2" per hour are expected. The most probable time for this snow to occur is between midnight and 6 a.m. Wednesday morning.
After that initial burst of snow, expect a dry slot to move in for much of the day on Wednesday. Although dry slots usually kill snow totals, in this case the dry slot will be our saving grace, as much of the precipitation that would fall on Wednesday would be rain anyways, as temperatures warm into the upper 30's. Do expect some rain to fall, but it will be light.
Then, as the low deepens and lifts to our northeast, it will pull in an arctic airmass. Winds will become strong out of the west as the cold front moves through, and temperatures will quickly drop below freezing Wednesday evening. Best of all, there will be a second burst of heavy snow behind this front. Right now, it looks like 2-4" of snow will fall, and this snow will be blown around by the gusty winds. Also, some forecast models are showing a nice band of heavy snowfall setting up somewhere in Southern Lower Michigan. If this band does develop, someone will be looking at 6+" of snow Wednesday Night.
As you can see, by adding up my totals you get a forecast of 4-10" of accumulation for our area. However, I must point out that only a few preferred spots (in the heaviest snow bands) will get 6+" of snow will the current forecasted storm track. Also, not all of the snow will accumulate on the ground, as temperatures will be close to freezing for much of the event. It is much more likely that we will see 4-5" of snow from this event.
However, the potential is still there for us to get a heavy band of snow sometime during this event. If we do, snow day chances greatly increase.
Finally, it is still possible that the surface low could track further south than is currently forecast. Once again, if this happens, snowfall totals and snow day chances will greatly increase.
The bottom line is that currently snow day chances look pretty unlikely for Wednesday and Thursday. However, it would only take a small change for snow day chances to increase.
The burst of heavy snow is still expected to occur out ahead of this storm, with anywhere between 2-6" of snow accumulating depending on how early this first wave of snow gets going. Once it starts to get going, snowfall rates of 1-2" per hour are expected. The most probable time for this snow to occur is between midnight and 6 a.m. Wednesday morning.
After that initial burst of snow, expect a dry slot to move in for much of the day on Wednesday. Although dry slots usually kill snow totals, in this case the dry slot will be our saving grace, as much of the precipitation that would fall on Wednesday would be rain anyways, as temperatures warm into the upper 30's. Do expect some rain to fall, but it will be light.
Then, as the low deepens and lifts to our northeast, it will pull in an arctic airmass. Winds will become strong out of the west as the cold front moves through, and temperatures will quickly drop below freezing Wednesday evening. Best of all, there will be a second burst of heavy snow behind this front. Right now, it looks like 2-4" of snow will fall, and this snow will be blown around by the gusty winds. Also, some forecast models are showing a nice band of heavy snowfall setting up somewhere in Southern Lower Michigan. If this band does develop, someone will be looking at 6+" of snow Wednesday Night.
As you can see, by adding up my totals you get a forecast of 4-10" of accumulation for our area. However, I must point out that only a few preferred spots (in the heaviest snow bands) will get 6+" of snow will the current forecasted storm track. Also, not all of the snow will accumulate on the ground, as temperatures will be close to freezing for much of the event. It is much more likely that we will see 4-5" of snow from this event.
However, the potential is still there for us to get a heavy band of snow sometime during this event. If we do, snow day chances greatly increase.
Finally, it is still possible that the surface low could track further south than is currently forecast. Once again, if this happens, snowfall totals and snow day chances will greatly increase.
The bottom line is that currently snow day chances look pretty unlikely for Wednesday and Thursday. However, it would only take a small change for snow day chances to increase.
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