NWS Birmingham has pretty much kept the forecast the same at this point for Monday afternoon through Monday night with the exception of pushing the main window of stronger to severe storms back, now at 2:00 pm Monday afternoon to 2:00 am Tuesday morning. Also, they have extended the Slight Risk for severe storms a little farther to the east to include locations along and west of a line from Autaugaville to Alexander City to Ranburne. A Marginal Risk continues for locations east of that line. All modes of severe weather still look to be possible: tornadoes, damaging winds up to 60 MPH, and hail of 1-inch in diameter.
Global models continue to show that there will be shear values around 60 knots, along with low-level helicity values up to around 300 m2/s2. We’ll also have more surface-based instability involved with this system as we’ll have more moist, warm, and unstable air move up into the area ahead of the cold front. Along with the front, a strong low-level jet will be working into the area ahead of it. While much of the activity may persist along a main squall line, there is a possibility for supercells to form and feed off of the instability that forms with the heating of the day.
This system is pretty similar to the last two severe weather threats that we’ve had over the past two weeks with the main difference being the increased surface-based instability. It’s not a guarantee that it will be more active than those two systems, but it is more likely that we will see a few warnings. I’ll get a better idea later tonight and tomorrow when the higher-resolution models come into view.
Bottom line… go ahead and have fresh batteries installed in your flashlights and weather radios. Have your supplies ready to go in your safety preparedness kits and have your place of safety cleared out and ready to go. This is definitely not a major threat, but all it takes is for one tornado to come down your street to make it a major event. Be ready… be prepared!