Friday, February 25, 2011

A Long, Thin Red Line

There was a very long, but quite thin, squall in the Southeast last evening and night. The top image shows the 0328 UTC radar mosaic (from the CoD page) with echoes of 50 dBZ or greater extending from western Kentucky southwestward to Louisiana. The middle image is from the NWS radar in northeast Mississippi (GWX) and shows a portion of the narrow squall line from a more detailed perspective, with stratiform precipitation trailing along quite a distance to the west. The length-to-width (or vice versa) aspect ratio of the radar squall line of strong storm echoes (>50 dBZ) is truly amazing.
The bottom figure shows SPC severe thunderstorm and tornado reports from yesterday afternoon, evening and night. The preliminary reports indicate two, extended,  nearly west-to-east swaths of severe reports with a long void between the swaths. It is interesting that the swaths of dense storm reports are oriented nearly orthogonal to that of the squall line. Interesting questions: if real, why the long gap from southwest Arkansas to eastern Kentucky without severe storms? When, if ever, will we be able to anticipate, on time frames of several hours to a day, such strange structures?

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