We are still watching the storm system developing to our west early this morning. It will be associated with a very sharp upper-level trough, causing rapid pressure falls and strong wind fields over Alabama, with winds increasing significantly by late morning and afternoon. Some non-thunderstorm wind gusts over 40 mph are possible. The wind fields and warm air moving in will produce large wind shear, with helicity values over 500 m2/s2 possible over central Alabama by noon.
However, the air is not unstable over central Alabama now, and it will have tough time getting that way.
The only dewpoints above 60 are along the Gulf Coast. As the main system rotates through today and winds pick up and veer more out of the south, dewpoints will rise to near 60 as far north as BHM, and slightly unstable air (CAPE up to 500 J/kg) will move in. So, expect thunderstorms, mainly with a threat of damaging straight line winds, this afternoon. The higher chance for damaging winds and tornadoes will be over south Alabama, in places south of Clanton, where the air will be much more unstable. Wind shear can make up for some lack of instability, but only so much. It looks like there won't be enough instability in the BHM area for significant severe weather.
One concern I have is that wind shear is enhanced along a warm front, and a front could set up near I-20 tomorrow afternoon. Still, the main upper-level energy will be pulling away by then most likely, so any threat for tornadoes here in central Alabama is very small unless something changes.
We'll be watching it closely. Jill Gilardi will have more on Fox 6 news this morning.
Dr. Tim Coleman