Sunday, December 18, 2011

Update on Major Winter Storm for Monday-Tuesday...

The above image shows the latest winter weather watches, warnings and advisories that are in effect in association with the major storm system headed toward the southwest and central Plains.

Blizzard Warnings are shown in orange.  Winter Storm Warnings are in pink.  Winter Storm Watches are in purple, and Winter Weather Advisories are in tan.

The latest water vapor satellite image (below) shows the center of the upper level storm system along the Arizona/Mexico border, and moving Eastward.

Precipitation will break out across the southern Rockies tonight and spread Eastward into the southern and central Plains on Monday and Monday Night.

Widespread, heavy snow is still forecast within the Blizzard and Winter Storm Warning areas.  Within the Blizzard Warning areas, strong, gusty winds will create white out to near white out conditions at times.  Travel is highly discouraged across these areas.

The latest run of the GFS computer forecast model continues to indicate widespread snowfall of 6-8 inches with localized amounts near 12 inches across southwest Kansas and portions of the Oklahoma and Texas panhandles by Monday night.  The image below shows the model's forecast of snow depth valid at 12 Noon CST on Tuesday (scale in inches at right): 

At this time, it appears that most of the heavy, accumulating snow will take place over the Western half of the Warning areas during the day Monday, and over the Eastern half of the Warning areas during the period Monday afternoon to sunrise on Tuesday.

As an example, the graph below shows a composite of all of the computer forecast model output for Dodge City.  The average snowfall forecast of all of the models is indicated by the line of small squares:

As you can see, the model average is calling for just over 10 inches (follow the purple arrow from the circle over to the scale on the left hand side) of snow to be on the ground at 12 Noon CST on Tuesday in Dodge City.  If you trace the squares backward in time, you can see that the models are forecasting most of the snow to fall in Dodge City between about 3pm Monday and 6am CST Tuesday.  You can see that a bit better on the cleaned-up graph below (I've taken out some of the other lines, etc. on the same image):

This is a potentially dangerous situation, particularly in the Blizzard and Winter Storm Warning areas.  Please plan to remain indoors in a safe place until this storm system passes.  Listen to local media or other trusted sources for the latest updates for your area.

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