Wednesday, January 11, 2012

Midwest Winter Storm Update- 1/11/12 Afternoon

We have a lot to get through today, so let's get started.
DENDRITE GROWTH ZONE (DGZ): The DGZ is basically the area in which the most snow will fall. Dendrites are actually snowflakes, and the Dendrite Growth Zone indicates the potential for snowflakes to pile on top of each other, particularly dendrites, for maximum accumulations.

Hour 24 Forecast
At hour 24, the SPC's SREF Ensembles are predicting there to be a DGZ in east Iowa and Northwest Illinois. This could be where some of the heaviest accumulations occur based on this and other factors.

Hour 30 Forecast
At hour 30 we see a pretty sizable and sustained DGZ setting up in central Illinois into northern Illinois. This could also be an accumulating area, but because the DGZ is then supposed to move north, the accumulations will not be as significant.
Hour 33 Forecast
By hour 33 the DGZ has moved into Chicago and Lake Michigan, moving towards Michigan. This will occur as the system itself moves on away from the Great Lakes and finishes its business.


Hour 36
At Hour 36, the heaviest snowfall appears to be located in North Illinois and extreme east Iowa, where we expect the system to have the most effect. It would not surprise me to see the dark blue (4-5 inches of snow in 12 hours) to be moved a bit west a bit farther into Iowa.
Hour 48
At Hour 48 we are seeing the big snow move off into Canada, with some lingering snow from the storm combining with Lake Effect Snow (LES) to make for a snowy Michigan state.

The purple areas are in a Winter Weather Advisory, while dark blue is a Winter Storm Watch.

We will be issuing many short posts with images on here in the next few days as we try to provide you with as much information as possible. Stay safe.

12 Hour Forecast Snow Accumulations- SPC SREF

Hour 36

Hour 48

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Afternoon Snowstorm Update

Amounts for Chicago have risen to 4-12 inches, with the GFS and NAM at opposite ends, respectively. The Chicago NWS Office is going for 4-8 inches, so we will have to see. Model update this afternoon.