Update on Severe Thunderstorm Threat

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Update at 3:11pm. The 3:08pm Ft. Smith NWS radar shows strong thunderstorms starting to develop from the Ozarks in NW Arkansas to west of Ft. Smith. This may be the initial development of severe thunderstorms in the region.



Original post:

At 2:55pm CDT, the threat area seems to be a little clearer. The satellite image below is from 2:31pm CDT. The main area where tornadoes and thunderstorms with damaging winds and large hail appears me to be in the area outlined in yellow.

The arrow points to a weak low in the upper atmosphere moving east near the KS-OK border. A weak wind shift line extends across northern Arkansas. The air in northeast Oklahoma and Arkansas just south of that line is extraordinarily unstable. The wind shear in the upper atmosphere has "improved" the last couple of hours for supercell development and the supercell index is now well beyond the threshold of 4 (see below).

While the greatest threat is along and just south of the boundary, if you live in the area outlined in yellow, keep an eye out on the weather in the next few hours.

This is not to say that severe thunderstorms will not occur elsewhere, just that this is the greatest threat area at the present time.


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