The latest model runs are out from the National Weather Service, and forecasts are still calling for a threat of severe thunderstorms and isolated tornadoes for late Saturday night and very early Sunday morning.
A squall line is expected to form in Mississippi tonight, and move eastward to reach the Mississippi-Alabama border between 8 p.m. and midnight. Ahead of this squall line some supercell storms may form, which may produce as isolated tornado or two, but nothing like the long-track violent tornadoes often seen in springtime outbreaks.
The line of storms will move into the metro Birmingham area sometime between midnight and 4 a.m.on Sunday. Again, the main threat is straight-line winds from severe thunderstorms inside the squall line, but isolated tornadoes are still possible. The line should move out of the metro area before church services begin, roughly 9 a.m.
It's advisable to have a NOAA Weather Radio handy tonight, and set where a warning issued by the NWS will trigger an alarm to wake you up.
Temperatures today will climb to the lower to middle 70s ahead of the storm line, high enough to perhaps break the record of 73 degrees in Birmingham for December 21. As the storms pass on Sunday, temperatures will start out in the upper 60s but fall to the middle 40s by nightfall. Highs through Christmas Day will top out in the upper 40s, with nighttime lows in the upper 20s.