11 February 2013

Tornado Strikes Hattiesburg MS. Tornadic Storms Rumbling into South Alabama As well.

Posted by Dan Satterfield

There is only weak instability but the wind shear is very conducive to tornados ahead of a cold front. Meteorologists look at a particular type of low-level wind shear called the storm relative helicity. Values above 200 are a warning sign and above 300 are a BIG warning to look for tornadoes.  I am seeing values over 600 across South AL now so the threat remains.

This is Storm Relative Helicity over MS and AL tonight. Image from NOAA SPC Norman,OK..

This is velocity data from the NOAA Nexrad Doppler radar. It shows strong winds toward the radar, coupled with strong winds away. A classic indication of an intense rotation.