A strong cold front will move southward today, moving through Alabama tonight. Out ahead of it, SW flow will bring in warm, moist air. Upper-level dynamics will not be all that strong, but models do indicate a weak wind speed maximum at 500-300 mb, which could enhance thunderstorm development by afternoon. Still, the main focus for storm development will be ahead of the cold front itself.
Expect scattered showers and thunderstorms to develop in the moderately unstable air (CAPE above 1000 J/kg) as far south as north AL this afternoon. The main area of storms will probably form into a line as they move into north Alabama by 6 pm, and through BHM around midnight. Rainfall amounts may average 0.25-0.50″, with some spots getting close to an inch.
Wind shear and instability may be enough for a few severe storms, with the main threat being damaging winds. But, with wind shear in place, it’s hard to rule out an isolated tornado. The highest threat for severe weather will likely be north of I-59, since the storms will likely be slowly weakening as they move south after sunset (cooling ground temperatures will lead to more stable air).
It will get much colder behind the front tomorrow and Friday, with highs only in the 50s with windy conditions tomorrow, and lows tomorrow night and Friday night well into the 30s.
