Effect of snow depth errors on 2-m temperatures in Wisconsin, 8 January 2003

Abstract

Here we examine a case where the Eta was too cool on 2-meter temperatures in WI by as much as 9°C on the afternoon of 8 January 2003, in its 12 UTC forecast on the same day! The Eta forecasts showed forecast 2-m temperatures actually becoming lower at 21 UTC on 8 January 2003 as the initial forecast time approached the event, even though forecast 850-hPa temperatures increased by 4-6°C during that same period.

In this case, we will show how the Eta model initial snow conditions were incorrect for 12 UTC 8 January 2003, how that error affected the forecast, and how the snow cover/snow depth error arose.

Learning objectives

In this case study, the main lessons are:

  1. Check surface initial snow conditions to make sure they are reasonable.
  2. Check continuity in the initial snow field to make sure evolution of related fields is consistent.
  3. Understand the sources of error in initial snow conditions.
  4. Make adjustments to correct for errors found using the above techniques.

In going through this case, when you open a separate graphic, an image or loop will pop up in a separate window. If one is already
displaying, it will be replaced by the one you just selected. Loops automatically start looping. To freeze a frame, click the Stop button .
To advance one frame, use the Plus 1 button . To resume looping, use the Forward button . Loop speed is increased by
repeatedly clicking the Fast button and decreased by doing the same to the Slow button .

 

Credits

by Dr. Bill Bua

Thanks to:

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