Tuesday, November 29, 2011

A Look At Yesterday Evening's Snow in the Deep South...

The image above shows snow depth as estimated by satellite imagery and computer models across the middle and lower Mississippi River Valley region at 6am CST this morning.   This particular image is from the Interactive Snow Information site via NOAA.  Below is a slightly different (geographically speaking) representation via NOAA's National Snow Analysis Center:

As you can see on both of the images, there are 2 patches of heavier snow depth indicated (on the order of 4-8 inches):  the first over extreme northeastern Arkansas, and the second over southeastern Missouri.  In fact, storm reports indicate 8.0 inches of snow fell near Paragould and 6 inches of snow fell near Jonesboro, both in Arkansas.  A report of 4.5 inches of snow came in from Caruthersville, Missouri:

Yesterday evening I posted an image from the experimental HRRR forecast model, which was calling for locally heavy snow across much of this region yesterday evening and overnight.  Below is the accumulated snowfall forecast from that model valid at 6am CST this morning, the same time that the observations were taken on each of the 3 images above.  The image was produced by the model at 5pm CST on Monday, approximately 13 hours before the valid time:

As you can see, the model did an outstanding job forecasting the heavier snow band across extreme northeast Arkansas and southeast Missouri.  It correctly forecast 6-8 inches of snow across this region (darker yellow and orange colors on the image).

On the other side of the coin, the model over-forecast the magnitude of the snowfall in Memphis, calling for 3-4 inches (around 1 inch was reported in most areas).  Truth be told, had the ground been colder in Memphis, they would have had more significant accumulation (and this was pointed out in the posts that I made yesterday afternoon).

All in all, I'd say the HRRR performed quite well in this event, and if you ask any meteorologist, snowfall forecasts are among the toughest calls.  I plan to keep an eye on the performance of this model in other snow events this winter and will post any relevant updates and/or observations.

In fact, it looks like we'll have an opportunity to test out the model this weekend in the Plains.  Watch for a more detailed post on this impending winter storm later this evening...

If you enjoy reading 'The Original Weather Blog', please be sure to "like" our facebook page!

No comments: