Potentially Historic Storm Set To Punish SE Michigan

Hello to all. Since last night the trend on the forecast models have come into much better agreement with regards to SE Michigan getting a potentially historic winter storm. Nearly all reputable models now show SE Michigan receiving over a foot of snow over a long multiday period that will likely range from Monday Night into early Thursday Morning. I already explained last night why this storm has the potential to be so notable, and it appears that it will indeed be a notable storm for SE Michigan...perhaps historically so. Tonight's post will focus on showcasing just how much snow could fall on SE Michigan, what the 5 major models show, an extremely preliminary snowfall forecast, and the adverse effects this storm could have on SE Michigan.

How Much Snow SE Michigan Could Receive:

It appears that there will be two waves of snow with this winter. The warm-up act before the main show will occur on Monday Night and early Tuesday Morning. As warm moist air advects northward from the Gulf of Mexico, snow will likely break out over much of the Upper Midwest and Great Lakes region. The following image from the NAM model, valid at 1:00 a.m. Tuesday Morning, shows this nicely.

There is an incredible spread between the models in the amount of snow that will fall on Monday Night into early Tuesday Morning. The NAM shows about 5-8" falling, which would be a winter storm warning criteria event in and of itself. On the other hand, the GFS and ECMWF show only about 1" of snow falling in this time period. I personally believe that the NAM is overdoing the amount of precipitation that will fall in this timeframe, while the GFS and ECMWF are underdoing it. I feel that about 2-4" of snow is likely to fall during this timeframe. A snow day on Tuesday is unlikely, but not out of the question if the NAM's current depiction of events is close to reality.

The second wave of snow, which will start early on Wednesday Morning and continue well into Wednesday Evening, is the one that is really going to bring the pain to SE Michigan. Almost every model over the last day has shown SE Michigan getting about 12-18 hours of extremely heavy snow on Wednesday. The following image from the GFS model, valid at 7 a.m. Wednesday Morning, showcases this nicely.

I really can't understate how impressive this period of snow could be for you guys. Snowfall rates over 1"/hour are likely to occur for an extended period of time, centered around the Wednesday Morning rush hour, which will essentially make travel impossible at that time. Convective snow is possible, which means you may hear some thunder along with the snow. Winds will also be howling throughout the event, creating localized whiteout conditions.

What The Five Major Models Show:

GFS:

The GFS has minor snowfall accumulations on Monday Night, then tracks the low pressure system from Northern Louisiana, to Northern Mississippi, to Central Kentucky, to Southern Ohio, to Southern Pennsylvania. The best snows occur just south of Lake Orion, but Lake Orion would still make out nicely if the GFS scenario happened with about 1" of snow on Monday Night and about 10-14" of snow on Wednesday.

ECMWF:

The ECMWF is the absolutely jackpot for Lake Orion, giving the area minor snow accumulations on Monday Night, followed by the main low pressure system tracking from Little Rock, AR to the Missouri Bootheel to Terre Haute, IN to Cleveland, OH. This is a benchmark track for great snowfall in Lake Orion, and the ECMWF certainly shows that, with about 1" of snow on Monday Night and then about 14-18" of snow on Wednesday.

NAM:

As mentioned earlier, the NAM has about 5-8" of snow falling Monday Night, although I believe this is overdone somewhat. The NAM only runs out to 84 hours, so I can't say with certainty what it would show for SE Michigan on Wednesday, but I feel it would likely be close to what the ECMWF shows.

GGEM:

The GGEM is by far the biggest outlier among the five major models, tracking the low pressure system from SW Louisiana to North Carolina. The GGEM would result in little to no snow for Lake Orion, but it has little to no support from other models or its own ensembles and its handling of the southern stream energy is wacky. Therefore I will discount its solution for now.

UKMET:

The UKMET tracks the low pressure system from Arkansas into NW Pennsylvania. Precip data for the UKMET is hard to find, but based on the track I have to believe its snow totals are between the GFS and ECMWF.

Preliminary Snowfall Forecast:

Obviously the models are converging on a solution that would result in a historic winter storm for SE Michigan. As I mentioned earlier, I expect 2-4" of snow to fall on Monday Night for SE Michigan. For Wednesday's forecast, I will use a blend of the GFS and ECMWF models, as they both appear to have a good handle on this storm. Therefore, I am forecasting 10-18" of snow to fall on Lake Orion and much of the rest of SE Michigan on Wednesday, save for lower amounts to the north of I-69. although as the storm draws closer I hope to hone in on amounts a little better. I know 10-18" of snow falling on Lake Orion on Wednesday for a storm total of 12-22" sounds unbelievable, but this really does look like a once in a decade event for SE Michigan. There is still some bust potential, but at this point in time it would take a fairly significant shift to the north for Lake Orion to have trouble with ice as opposed to snow. Conversely, it would take a fairly significant shift to the south at this point for Lake Orion to be north of the main snow axis.

Impacts From This Storm:

Obviously, the potential impacts to SE Michigan from this storm could be fairly significant. As I mentioned earlier, snow will likely fall at a rate of over 1"/hour for an extended period of time, meaning snow plows will just not be able to keep up. I'd expect even the main roads to be a relative disaster for the Wednesday Morning commute, and Wednesday Evening may not be much better. Obviously non main roads which don't get plowed until after the storm will likely be nearly undriveable, what with 10-18" of snow accumulating on them. Winds will also be quite strong creating low wind chills and near whiteout to whiteout conditions for much of the storm.

With regards to snow days, on Monday you obviously won't get one as no snow will have fallen yet. Therefore I will set the snow day grade to an E.

On Tuesday, you have a chance, if the NAM's depiction of the initial wave of snow on Monday Night is correct. However, as I've mentioned several times before in this blog, I believe the NAM is overdoing the amount of snow that will actually fall on Monday Night. However, I will account for the fact that it could be close to correct and set the snow day grade on Tuesday to a D.

On Wednesday, I really don't think there's any doubt that you guys will have a snow day. The morning and evening commutes will be a living nightmare. I will set the snow day grade on Wednesday to an A with no hesitation.

On Thursday, while I am a little more uncertain than Wednesday, I believe the non-main roads will still largely be unplowed, and I will also set the snow day grade on Thursday to an A.

Finally, Friday. Friday is slightly tougher to call, especially 6 days out...but I will still attempt to make a best guess for Friday's chances. To do this, I will look back to the January 1st, 2008 storm, where Lake Orion received anywhere from 14-16" of snow, depending where in town you measured. That was a completely different storm setup than this one, but totals will likely be similar, so I'll use it as an example anyways. With that storm, we received a snow day on our first day back from winter break, which was three days after the storm occurred. With that in mind, I believe it is more likely than not that back roads will still be in poor enough shape for you guys to receive a third snow day on Friday. I will therefore set the snow day grade to a B for now, although this by far is the day I feel least confident about.

Day By Day Snow Day Grades:
Monday: E
Tuesday: D
Wednesday: A
Thursday: A
Friday: B

In summary, I am highly confident that SE Michigan will receive a significant, long lasting winter storm. If the upper end of my possible accumulations is reached, this storm could potentially be historic. Due to this, travel will obviously be significantly affected, and I am highly confident that Lake Orion will see at least two snow days in the upcoming week.

On a final note, although I know I am forecasting extremely significant accumulations, please do not use this blog for emergency planning. Although my weather knowledge has grown significantly over the past few years, I am still definitely an amateur. Listen to what the professionals tell you over the next few days with regards to what preparations you should make, because they have a lot more weather knowledge than me. I expect this storm to get significant media coverage starting tomorrow.

As always, feel free to leave questions and comments in the comments section below. Thanks for reading, and stay tuned to the blog over the next several days.