With sunshine and warm, humid air being transported in from the Gulf of Mexico, the air has become unstable over Alabama this afternoon, with instability increasing from east to west. Also, a very well-defined area of enhanced convergence has been persistent from NW Alabama into eastern Mississippi, with thunderstorms developing there over the past few hours.
The most persistent intense storm has been the supercell storm in northwest Alabama which did damage in the Haleyville area. However, storms farther south in that line, from Pickens county into Greene and Sumter counties, are also rotating intensely in this high shear environment, and tornado warnings are in effect there.
With the unstable air and wind shear, expect this line of storms to continue to move slowly eastward over the next 2-3 hours. The air further east, near BHM, is not quite as unstable, but the unstable air is moving east about as fast as the storms are, so these storms very well could affect Tuscaloosa, Walker, Jefferson, Shelby, and Bibb counties by rush hour.
With the main upper level storm and cold front still west of the Mississippi River, expect storms to continue to be a threat through the evening, and a tornado watch may be issued for more of Alabama soon. Severe storms are expected to rapidly develop over western MS and TN anytime, eventually developing into a squall line. It should finally move through tonight, probably after midnight, with damaging winds and isolated tornadoes.
