Saturday, December 3, 2011

Update on Winter Weather Event #1: Snow Getting Underway in High Plains...

Snow is spreading from the central and southern Rockies into the adjacent High Plains early this morning, as noted on the latest radar mosaic image above.  A mix of sleet, snow and in some cases freezing rain or freezing drizzle is taking place over southwest Kansas and the Oklahoma/Texas panhandle region (some of which is too light to be detected by the radar).

A Winter Storm Warning is in effect for the areas shaded in pink on the image below, with a variety of Winter Weather Advisories in effect for the areas shaded in tan:

Here are some snowfall totals so far, starting in the Southern portion of the region:

...and in the Northern part of the region (keep in mind, we're just getting started in Kansas and Nebraska):

When reading the blue text boxes on the 2 images above, the number immediately following "Event:" refers to the snow depth in inches.  For example, the box near Oberlin, KS says "Event:  3.3 SNOW".  This means that 3.3 inches of snow was measured at Oberlin.

As I pointed out in a couple of different posts yesterday, among all of the computer forecast models, the SREF model seems to be handling the snow accumulation forecast for this event very well at this time.  For example, on the latest image valid 12 Noon CST today, 4-6 inches of accumulation are forecast from northwest Kansas into southcentral Nebraska, and the reports and radar trends so far indicate this is a very good forecast:

Please note, the scale in inches of snow is located on the lower left portion of each of the SREF images.  By 3pm CST today, a narrow band of 6-8 inches of accumulation is forecast across this same region:

...and here is the forecast valid 6pm CST this afternoon/evening:

The HRRR forecast model, an experimental, small-scale model, is a bit more aggressive with snowfall totals across extreme northwest Kansas into central Nebraska, as noted on the image below, valid 6pm CST this evening:

As you can see, it is forecasting a snow accumulation of 2-3 inches higher than the SREF model (in the darker orange shaded areas).  I can certainly see this coming to pass in association with any heavier snow bursts that set-up across this region.

By Midnight tonight/Sunday morning, accumulating snows will have spread into northeast Iowa and across southeast Minnesota/northwest Wisconsin, as indicated by the image below:

Strong and gusty North winds will cause widespread blowing snow across the affected areas, and travel is highly discouraged across these areas today and tonight.

The forecast snowfall amounts that we're seeing (especially when paired with the current observations) suggest that "Winter Weather Advisory" criteria will be exceeded across portions of at least southcentral or southwest Nebraska today.  I would expect to see some type of advisory upgrade in this region.

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