Thursday, January 10, 2013

5:10pm Weather Update

Continuing to keep an eye on the Sunday-Tuesday time frame for parts of Missouri, Illinois, Indiana, Arkansas, Kentucky and Tennessee as the possibility of wintery weather exists.

Morning computer model data is in and the battle lines are still drawn.  NOAA’s global forecast model, the GFS, continues to bring in cold air at both the surface as well as a few thousand feet up in the atmosphere.  The European forecast agency’s computer model, the ECMWF (Euro), continues to bring shallow cold air near the ground in under “warmer” air a few thousand feet up.  The GFS suggests rain with a brief changeover to snow before the moisture moves out.  The Euro has moisture overrunning the cold air which would fall as rain and then freeze near the ground.

A couple of quick meteograms.  First, a look at surface the surface temperature in St. Louis.  Pretty obvious when the cold front passes.
Click image to see larger version.
Next, a look at freezing rain accumulation for Evansville, IN.  Note the scale on the left side of the image.  It keeps the accumulation minimal.
Click image to see larger version.
The latest forecast from the Hydrometeorological Prediction Center keeps the possibility of freezing rain/sleet in the forecast from 6pm CT Saturday through 6pm CT Sunday.
Click the image to see larger version.
The above is a probability forecast for 0.01" or more of ice.

There has been a subtle shift to the southeast in this morning’s run of the European forecast model, but I think it is too early to get in to details like that as the data will flip-flop around a bit over the next couple of days.

A forecaster from the National Weather Service office in Paducah, Kentucky described it best in their afternoon forecast discussion… “There is little reason to expect these rather subtle details to be handled well by the models at this time range… Will have to wait for a better, more coherent, clue which may not show up until Saturday.”

FREAK-OUT-METER:
  • Southeast Missouri: 3
  • Southern Illinois: 3
  • Western Kentucky: 3
  • Central Indiana: 3
  • St. Louis metro: 3

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