I know it's Christmas and it might be difficult to stay focused on watching the weather. But, you need to pay close attention to developments during the late afternoon Tuesday and through at least the early overnight into Wednesday morning.
We have a classic system Winter severe weather system developing. This includes wind shear that's nearly off the charts. We'll have winds just overhead at over 80mph at around 5,000ft. Instability will be increasing through the day as a warm front lifts to the north. The warm front is the key determining factor in just how bad the weather gets. I will be monitoring the position of that front all day to determine the northern extent of the dangerous weather.
The Meteorology: Let's toss out a few maps to help me explain my case. This is a severe weather chart based off the NAM. The closely packed contours are indicating the amount of spin in the atmosphere. The colored areas are showing where the instability is the greatest. It's where these two areas match up where the tornado risk is highest. The first map is for early evening and the second map is a projection for around midnight.
The Storm Prediction Center has our highest risk for tornadoes south of I-20 and especially to the Southwest of Birmingham extending westward into Mississippi. Don't get me wrong. We could have tornadoes anywhere in the state tomorrow, but this is likely to be where the worst tornadoes develop.
What to expect? We will make it through most of the daytime hours with only rain and temperatures reaching the lower 60s. It will be a cloudy Christmas Day. In extreme South Alabama, we could see tornado warnings as early as the afternoon hours. For the Fox 6 area in Central and North Alabama - it will be mainly rain. My concern comes after sunset. We will first see a flooding threat, followed by a tornado threat, and then system eventually ends as a linear type system resulting in straight line winds closer to midnight as the system marches from West to East.
Peak threat time: I think we'll see th highest risk for severe storms between 5pm and midnight. This includes the threat for some longer track tornadoes south of I-20 and west of I-65. Essentially - the closer you are to Mississippi and the farther south you are the worst weather.
Challenging Forecast: This is not a cut and dry forecast. It's easy from the standpoint of having extreme wind shear. That's a key ingredient in tornado formation. In fact, it's probably the most critical one. However, instability is also important. With the amount of wind shear we do have - it will not take much instability to produce a tornado. The challenge for us is to figure out how far the warm front will move northward. Since we're expecting rain during the day - it will be difficult for the warm front to have much progress in its track to the north. Based on the models I have - I think the warm front will at least make it to the Birmingham area. This means the greatest risk should remain Birmingham southward. However, we still could see some damaging winds and stronger storms to the north - just not as widespread or organized. This is not a system to the extent of April 27th, but it is a system we must monitor closely and not be caught off guard.
Fox 6 will be hitting this hard over the next 24 hours. Please stay with us online at www.myfoxtracker.com and via social-media. You can follow me on Twitter at jpdice_Fox6. In addition - make sure your NOAA weather radio is working.
Fox 6 Chief Meteorologist