We will be dealing with both the potential for severe weather and heavy rainfall/flash flooding tomorrow night into Wednesday.
A quasilinear convective system (QLCS) along/ahead of a cold front is going to track from west to east across the area tomorrow night into Wednesday morning. QLCS is simply a technical term for a squall line.
The SPC still has the area in a slight (level 2 out of 5) risk for severe weather tomorrow. While the greatest threat for severe weather will likely remain to our west, parameters will be favorable for severe thunderstorms tomorrow night.
Afternoon model guidance is projecting CAPE values to increase to 800 to 1500 j/kg generally after 7:00 PM with 0-1 km wind shear of 30 to 40 kts, 0-6 km wind shear of 50 to 70 kts, and 0-1 km storm relative helicity (SRH) values of 300 to 500 m^2/s^2.
All severe hazards (tornadoes, damaging winds, and large hail) will be possible.
One thing to watch for will be development of any isolated/discrete cells ahead of the QLCS. These could pose a higher tornado threat. Right now the only model showing this possibility is the HRRR and it mostly keeps them confined to south Alabama. Our main severe weather threat is likely to come from the QLCS.
It is also worth noting that the NAM-3km and HRRR have the QLCS less defined than earlier in the day as it moves across the area tomorrow night/early Wednesday morning.
In addition to severe weather, heavy rainfall/flash flooding will also be a concern. Generally 2 to 3 inches of rain is forecast, but locally higher amounts will be possible.
NWS Mobile has an elevated risk for flash flooding for northern Escambia, Santa Rosa, and Okaloosa counties and a slight risk elsewhere. Minor river flooding will also be possible.
It is hard to be more specific with timing as model guidance differs on when the QLCS will move through. However, it does look like storms will be out of the area by Wednesday afternoon at the latest.
On another note, it will also be quite windy tomorrow due to gradient (non-thunderstorm) winds. A wind advisory is in effect from 9 AM tomorrow morning through midnight. Sustained winds of 15 to 25 mph are expected with gusts up to 40 mph.
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