Final Prediction

The all-important question that will determine snow accumulations in Lake Orion tonight is...will we be dry-slotted? Dry-slotting occurs when dry air moves in behind the low pressure system, resulting in a break in snowfall. We probably need 4+" to get a snow day tomorrow, and as long as we don't get dry-slotted for an extended period of time, that will probably happen. This is a heavy, wet snow that will make rush-hour traffic tomorrow morning terrible, especially as there is probably a layer of slush under the snow. What I will say is that it is a tough call as to whether or not we in Lake Orion will get a snow day tomorrow, as we will probably be right on the edge of the extended dry-slotting. However, I think we manage to pick up around 4.5" of snow tonight for a storm total of around 6", which is probably good enough for a snow day tomorrow.

Therefore, my prediction is YES, we will get a snow day tomorrow. A tough first prediction to make for sure though, and I'm not just saying that so I have an excuse if we have school tomorrow. If we have school tomorrow, I will freely admit that I was wrong.


Here is my snow day chances map. What is the 50% line? It is the general snow day line. Areas to the N of the line have a greater than 50% chance of a snow day, and areas to the S of the line have a less than 50% chance of a snow day.

EDITED MAP: Because I mixed up Lake Orion and Flint.

Update

The forecast seems to be on track. Although the low pressure system is tracking further west than expected, we somehow have managed to have all of our precipitation fall as snow. The National Weather Service therefore upgraded Oakland County to a Winter Storm Warning. Although we only have 1.4" of snow so far (at my house), 3-7" more of snow is expected tonight. Therefore, I will keep the snow day alert level at high

To the person from Carmen-Ainsworth High School: I will make a prediction for that high school and include in my prediction tonight a graphic showing the general "snow day" line. Areas to the north of this line will likely close school tomorrow, while areas to the south of this line will likely not close school tomorrow.

Update

One problem with this storm is that the area of precipitation is not as large as expected. This may lead to the precipitation ending early, and less snow falling. Another problem is that the surface low track may be further west than expected. If this occurs, the changeover from rain to snow could occur faster than expected. If these trends continue, I will put out a new snowfall map with lower snowfall totals in a few hours, and also downgrade our alert level to medium. For now though, I'll stick with the going forecast.

Everything on track; raised alert level to high

Snow Day Alert Level: [Low] [Medium] [High] [Very High]

Read my detailed discussion in the last post, and my snowfall map in the last post, as those are still valid. And as I said in that discussion, if they were still valid this morning, I would raise the alert level to high. Currently, the National Weather Service is forecasting Lake Orion to get 4-7" of snow. I'm forecasting 5-9", and I believe that the NWS will join me in forecasting that much this afternoon. This is because the snow is occurring further south than where the NWS forecast it to fall. Therefore, we will likely get a quicker changeover to snow than is currently forecast, and thusly more snow. Other National Weather Service offices have bumped up snow totals for this event, and I believe that our National Weather Service office will soon follow.

I will make a definitive "yes" or "no" prediction on whether or not we will have a snow day by 7:35 p.m. tonight.

Use the comment feature! Ask me a question about this storm and our snow day chances through the comment feature, and I will answer it. I'll be updating this blog several times throughout the day, and will answer your questions in the updates.

MEDIUM risk of a snow day Monday.

Lead Story: Temperatures likely cold enough for snow; alert level raised to medium.

Snow Day Alert Level: [Low] [Medium] [High] [Very High]

Discussion: A low pressure system currently located in Western Kentucky is going to move to the NNE tomorrow and bring an area of heavy snow to SE Michigan from the early afternoon on. The forecast models are likely initiating temperatures a little too warm, so most of the precipitation should fall as snow. Therefore, my snowfall map will bump totals up a little bit over what most people are saying, as the heaviest precipitation will fall at the start of this event, and therefore we could receive a good more snow than forecast if precipitation starts out as snow, or if precipitation turns over to snow more quickly than expected. I expect a quick period of rain at the start of this event, turning over to snow sooner than expected. Why? Well for one, temperatures tonight are already 1-2 degrees lower than what was forecasted. Now, I know, 1-2 degrees doesn't seem like a big difference, but it could make all the difference with this storm. See, the heaviest precipitation will fall at the start of this event, so even a changeover to snow an hour quicker than expected could result in an additional inch or two more than what was forecast. Another thing that points to possible heavier accumulations is that the precipitation is starting quicker than expected. The earlier precipitation starts tomorrow, the less time temperatures have to rebound. Therefore, I expect it to start snowing sooner than expected tomorrow, resulting in the higher accumulations than generally forecast in my snowfall map below.

So, expect precipitation to begin around noontime tomorrow. It will likely start as rain or a wintry mix, transitioning over to heavy snow sometime in the early afternoon. The snowflakes at the start of this event could be huge, and snowfall rates could easily exceed 1" per hour. Snow will then continue to fall into the evening and overnight, and this snow will continue to be heavy at times, especially if we can get some lake enhancement going overnight as winds shift to the Northeast. Wraparound snow showers will then occur on Monday as the low moves away from MI.

Now, to discuss snow day chances. Why didn't I move our alert level to high? One reason: the high bust potential with this system. Just as a quick changeover to snow will result in an additional inch or two with this system, a slow changeover will result in an inch or two less than forecasted. Therefore, I played it safe for now and kept it at medium. If the current forecast holds up tomorrow morning, I will raise our chances to high. There are a lot of things going for a snow day with this system. Firstly, this will be a long event, with snow potentially falling for 24 hours from Sunday Afternoon to Monday Afternoon. This means that the plows will have to focus on the main roads, not the back roads. Also, there will be a lot of blowing and drifting of snow, resulting in major snow drifts on the back roads that will simply be impossible for buses to move through.

The bottom line: Currently forecasted accumulations would be enough for a snow day, but I will hold off on raising our alert level to high until the bust potential minimizes for this event.

Snowfall Map:

New Snowfall Map

Why the changes in the map? Well, the main difference is that the rain/snow line is probably going to be over SE Michigan. This will severely cut down on snowfall accumulations at the start of this event. However, a quick burst of heavy snow is still likely at the end of this event. Due to the fact that I am forecasting Lake Orion to get only 2-4" of snow now, I have lowered the snow day alert level back down to LOW. This is subject to change though, as a little further east track of the low could increase snowfall totals.

NOTE: After this system moves through, I'll be keeping an eye on a strong cold front that will come through on Wednesday Night. There could be blizzard conditions for a few hours with this cold front, and I'm actually a little more excited about that system right now, to be honest.

First Snow Map for Sunday Afternoon/Evening Snow Event

I'll post a detailed discussion of our updated snow day chances tonight, but for now, here's my first snowfall map for this system. As you can see, if these accumulations come to pass, it would be unlikely that we would get a snow day on Monday. Therefore, if future model runs support my current snowfall map, I will likely bump our snow day chances back down to low in my discussion tonight. However, there are still two days before this system hits, so snowfall totals still have a lot of time to be trended upwards. Stay tuned to this blog for details, and my detailed discussion will be up around 11:30 p.m. tonight!


EDITING to say sorry, but I won't have an update tonight. I'm tired, and the forecast models are all over the place. Suffice it to say, the chances of a snow day are diminishing. I will have a full discussion, and a new snow map, out when I wake up tomorrow morning.



Here's the map:

Snow Day Alert Level Upgrade

Based on forecast models coming together to give the Lake Orion area some very heavy snow Sunday Night through Monday Morning, I have upgrade the snow day alert level for Monday, December 1st to Medium.

Snow day alert level: [Low] [Medium] [High] [Very High]

Why I raised the alert level: The forecast models have all been showing some kind of storm system cutting through the Great Lakes and giving the Lake Orion area some amount of accumulating snow from Sunday Night through Monday Afternoon. Now, two of the biggest models, the GFS and the NAM, have come closer together with the latest model run. The good news is, both of these models now suggest that some very heavy snow is possible between Sunday Evening and Monday Morning as a low pressure system forms over Central Kentucky and moves north-northeastward through Ohio. Based on the latest runs of these models, one living in the Lake Orion area can expect precipitation to start off as a wintry mix Sunday Evening, transitioning to very heavy snow overnight on Sunday. This snow would continue to be heavy through around the noon hour on Monday, after which it would start to taper off.

Obviously, this system has the possibility to adversely affect travel Monday Morning, which might lead to a snow day being called by the Lake Orion School District. However, there are still several variables which could lead to a much lesser chance of a snow day. Perhaps the most obvious is that if the low pressure system moves a little further west than currently forecast, then the rain/snow line would also shift west and most of our precipitation could fall as rain. However, other variables such as if the low would even form, the strength of the low, and the timing of the precipitation are starting to be resolved, and I have therefore move the snow day alert level up to medium. Stay tuned to this blog for updates.

Potential snow days: Monday (12/1)

First snow day alert of the season

Based on the last two forecast model runs...I am putting our area under a snow day alert. This is the first snow day alert of the year.

Snow day alert level:
[Low] [Medium] [High] [Very High]

Reason for snow day alert: For two model runs in a row, a low pressure system has been shown developing in the Southeastern US and then moving NNE through Ohio. The models have shown heavy snow falling over SE Michigan some time between Sunday and Monday night.

Reason for level of snow day alert (low): This scenario has only been shown for two consecutive model runs. Therefore, this scenario may not come to pass at all. Also, it is still quite far away so the strength and timing of the system is still in question. As we all know, just as important as how much snow falls is when the snow falls. 6+" of snow does no good for a snow day if it all falls during the day and can therefore be plowed up at night. So for now, the alert level will be kept at low. Stay tuned to this blog for updates!

Potential snow days:
-Monday 12/1
-Tuesday 12/2

Monday/Tuesday Snowfall Forecast

Two weak systems have come together and induce surface low formation. This surface low will likely move just south of our area tomorrow, and this will provide the first widespread accumulating snow of the season for Southeast Michigan. There will likely be two different rounds of snow with this system. The first will occur as the surface low passes just to our south. This round of precipitation will start in the mid-morning timeframe tomorrow, and will continue until about rush hour tomorrow evening. This precipitation may start off as rain, but should quickly turn over to snow. Total accumulations for this first round of snow will likely be in the 1-3" range. Dry air will then work into the area late in the afternoon tomorrow, which will stop the snow for a while. However, a second round of snow is then likely to occur starting early Tuesday Morning as wraparound moisture and a favorable NNW wind off of Lake Huron will combine to send lake-enhance snow showers into our area. These snow showers will likely be heavy at times, and will probably give us at least another inch of accumulation, maybe even two. Due to this I am forecasting Lake Orion to receive 3-5" of snow with this system. This obviously won't be enough for a snow day, but it will be our first real accumulating snow of the season.

My forecasted accumulations between 8 a.m. Monday and 8 p.m. Tuesday

Monday Afternoon - Tuesday Forecast

Two weak systems will induce surface low formation over Lower Michigan on Monday. This will bring an abrupt end to the nice weather we will receive tomorrow, and will likely provide the first widespread accumulating snow of the season for Southeast Michigan.

Chance of Snow: 100%
It definitely seems like this system will form to the west of us, and then track over us bringing precipitation. Although the precipitation will likely start off as rain on Monday Afternoon, it should quickly change over to snow.

Chance of a Snow Day: 5%
The main snowfall will come at a fairly good time - approximately between 5 and 11 p.m. Monday Night - for receiving a snow day. However, what remains to be seen is just how much snow may fall. At this time, I am thinking that the Lake Orion area will only receive 2-4" of snow due to two factors. 1) The precipitation will likely start off as rain. 2) This low pressure system isn't particularly strong. However, if later model runs show that the low pressure system may be stronger, or that temperatures will be colder resulting in an all snow event, then snowfall amounts and snow day chances will have to be adjusted upwards.

The Bottom Line: This storm will probably bring the first widespread snowfall accumulations of the season to Southeast Michigan. However, the snowfall amounts will likely remain low enough to only cause a messy commute Tuesday Morning, not snow days.

Current snowfall forecast map:

Lake Orion vs. Rockford Forecast

72 degrees, but no sunshine during the game. I guarantee it!

LO-Fordson forecast.

Temperatures in the mid 30's at kickoff, dropping to the upper 20's by the end of the game. Skies will start off mostly clear, with clouds then increasing throughout the game. Virtually no chance of rain.

Why we won't get much snow today.

The bottom line is, this would be a great low pressure system track and would give us a lot of snow, but temperatures are simply too warm for snow to fall. Eventually later this afternoon and early this evening, temperatures will get cold enough for snow, but by then the low pressure system will be moving out of the area, leaving us with only a few hours of snow. Therefore, my new snowfall map has toned down the projected accumulations a lot.

Saturday...first moderate accumulation of the season?

On Friday, a strong cold front will move through the area. Ahead of this cold front, heavy rain and embedded thunderstorms will occur all day Friday, and into Friday Night. Behind this cold front, temperatures will quickly fall. These falling temperatures, combined with a low pressure system forming over NW Ohio or SE Ontario and then strengthening as it moves Northeast, will likely allow for some moderate snow accumulation to occur on Saturday Night. The forecast models are still in disagreement about the track of this low pressure system, which could lead to changes in its strength and location, which in turn would lead to different snow accumulation forecasts. However, one forecast model, the NAM has been relatively consistent, and that is therefore what I am mainly basing my forecasts off of. The NAM shows a surface low forming in Ontario, and moving to the Northeast while strengthening. Snow would wrap behind this low and impact us starting late Saturday afternoon and ending in the wee hours of Sunday Morning.

Chance of Snow: 70%

Reasoning: If the surface low takes a track too far to the east, we would likely see no snow at all. Otherwise, we will see a period of at least light to moderate snow, perhaps heavy at times.

Chance of a Snow Day: 0%

Reasoning: The accumulations won't be anything major, and the timing of the system (Saturday Night) is poor for a snow day to occur.

Predicted Accumulation: 1-4 inches

Reasoning: At this time, the low pressure system's track would support several hours of moderate snowfall. However, this prediction is likely to change somewhat. If the low tracks further to the east than forecast, or much further west than forecast, we probably will see less than 1" of snow. Conversely, if surface low formation occurs earlier than expected, and then the low strengthens more than expected before reaching us, we could see more snow than forecast. So, check back here tomorrow morning when I will issue my update on this system.

Here is my preliminary snowfall map for SE Michigan:

Upcoming Systems

For now, the storm system Friday Night is expected to pass a little too far to the east for us to get anything. I will keep watching this system though, and have updates if the track adjusts further west.

The system to watch, in my opinion, will move through from Sunday Night to Monday Afternoon. It will be a fast-moving system dropping out of Canada (known as a clipper) and could bring us a quick 1-2 inches of snow Sunday Night and Monday Morning.

I'll have more updates on these two systems when I come home from school today.

Regardless of if either of these two systems come to materialize, we should see more snow showers throughout this weekend and early next week, which should result in more dustings of accumulation like the one we had last Sunday Night.

Light Snow possible tonight

A band of precipitation is moving into Southern Lower Michigan. If the precipitation doesn't dissipate before it reaches Lake Orion, we will see a period of light snow tonight, transitioning to rain tomorrow morning. There will be almost no accumulation (even less than with the snow showers Sunday Night).

Bottom Line: Just another sign that winter is slowly getting closer.

However, there is a really interesting pattern that the forecast models are showing. This pattern is that of a secondary system moving in after a strong cold front comes through on Friday. If this holds, we may see an inch or two of snow Friday Night. I'll issue a more elaborate discussion tomorrow, if necessary.

First light accumulation?

For the time being today, there shouldn't be much precipitation other than the lake effect rain band that's about to move through the area. What precipitation falls today will be rain, perhaps with some sleet mixing in in the stronger showers. Then, in the late afternoon, an upper level low and accompanying cold pool will move to the north of the area. This will allow for numerous showers to form. These showers will start out as rain, then mix in with snow overnight.
Tomorrow, the showers will continue to be numerous as the cold pool (along with a shortwave) provides sufficient instability to allow for showers to form. The showers will end up transitioning to all snow by Sunday Afternoon as a strong cold front will pass through the area overnight tonight.

Also, these snow showers will have some lake enhancement. The winds will mean that the heaviest snow will fall along and south of the Detroit area. However, that won't make a lot of difference in this event, as almost everyone should see some snow, and roads will be too warm for any accumulation.

Chance of Snow: 80%
Temperatures will be cold enough for snow by tomorrow afternoon, and possibly tonight and tomorrow morning. Precipitation coverage will be high, so therefore there is a high chance of snow with this event.

Chance of a Snow Day: 0%
The roads will be too warm for any accumulation. Even if they weren't, there wouldn't be enough snow for there to be any chance of a snow day.

Predicted Accumulation:
-On warm surfaces (Roads, etc.): None. They will still be too warm for any accumulation.

-On cold surfaces (Grass, Car roofs, etc.): 0.5 inches. Snow showers will likely be heavy enough for some light accumulations on cold surfaces. If Lake Orion gets a heavier snow shower, we may even see up to a quick inch of accumulation. I will be measuring snow accumulation on my car roof for this event.

Bottom Line: A chance for almost everyone in Southeast Michigan to see their first snow.

Snow on Sunday

Two cold fronts will come through in the next few days, bringing an abrupt end to our summerlike stretch in early November. Indeed, after the second cold front comes through on Sunday, rain showers will likely mix with snow showers by sundown on Sunday, with all precipitation likely falling as snow Sunday Night.

Chance of Snow: 50%
Reasoning: Precipitation should fall Sunday and Sunday Night, and as of right now, temperatures support the precipitation changing over to snow by sundown on Sunday.

Chance of a Snow Day: 0%
Reasoning: A little snow may accumulate on grassy surfaces, but none will accumulate on the roads. The only effect this snow will have may be to make the roads a little slippery for the Monday Morning commute.

Predicted Accumulation: Less than 1"
Reasoning: There should be some minor accumulations with these snow showers, especially the heavier ones, but accumulation will be limited to grassy surfaces.

Bottom Line: I know not all of Lake Orion saw their first snow with the October 27-28 system, so this is a chance for more people to see their first snow. Other than that, this system is nothing special.

Strong cold front, then snow???

Enjoy the weather early this week, as temperatures will be in the lower 70's. However, by the end of the week, a strong cold front will move through. The early effects of this cold front could be horrible weather for the Lake Orion - Romeo football game Friday Night, as temperatures right now look to be in the upper 30's for that game. However, the cold temperatures will be the least of the weather problems. There is about a 50% chance of rain for Friday Night, and it is almost certainly going to be windy as a cold airmass moves in behind the cold front.

Then by Saturday Night, temperatures could be cold enough to support light snow showers. IF snow falls, accumulations would likely be very light, if the snow even sticks to the ground at all. The snow forecast has a high potential for change, as a few degree swing in temperatures will be the difference between getting rain or snow behind the cold front. Stay tuned to the blog for updates.