Sunday, November 22, 2009

More weather hype: snow for Thanksgiving?

There's a chance I might get to pull a Larry David—to be happy and cheery at others' expense. Why? Because on the upcoming biggest travel day of the year, Wednesday, we might get just enough snow to a) ski on and b) tie up traffic something awful.

Let me stress: might.

The models, this time of year, are less than stellar. Wednesday is still three days away. However, for several consecutive runs, the GFS model has bullseyed an area of QPF (precipitation) over the Twin Cities, with most of it looking to fall as snow on the back side of a progression of lows. Before you get too excited, consider the aforementioned inaccuracy of the models, the other models not quite showing the same thing (the NAM has most snow further east), the fact that this is a small area of precipitation so a small shift of a few dozen miles could make or break the deal, and the fact that the temperature will be near freezing, so a few degrees could make for a cold rain.

Now that I've sufficiently dampened enthusiasm, let's go to the video tape (as it were). Last night's 00Z (midnight CST for the GFS) model run showed the precipitation east of here. Since then, the following are the approximate QPF estimates for once the air column cools enough for snow. Here are 06Z, 12Z and 18Z runs. The contours are 0.01", 0.1", 0.25", 0.5" and upwards; 0.5" being dark blue.

So … that's three straight model runs with us getting at least three inches of snow, or so. This is all spun out the back of a second system and will hit warm, wet ground, so there's no telling how much will actually fall. But, it's certainly more than nothing. The next few runs should be very interesting, indeed, as well as whether other models jump on board. There will be much more to know to know tomorrow, and remember, IANAM (I am not a meteorologist).

A bit of good news if it does snow (or even if it doesn't): the models are showing a more muted warmup next weekend before the real cold comes in, so if we get a few inches of snow, with the current low sun angle, it might not all melt completely. Winter is certainly late, but it should be coming soon.

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