Alrighty, friends. Here is the deal: Upstream, thunderstorm activity is picking up across parts of Texas, Oklahoma, Arkansas and a sliver of Louisiana. These storms will ride a front to the east-southeast across parts of Louisiana, Mississippi, Alabama and Georgia through the day on Saturday. These storms will be working into an area with abundant moisture, higher-than-average instability and a ton of shear.
Because of that, the Storm Prediction Center has highlighted parts of the region with an Enhanced Risk for severe weather.
But despite the plump parameters, the SPC isn’t highlighting the area with a chance for copious amounts of different types of severe weather. Instead, the focus is on wind from an MCS.
From the SPC:
Of more concern will be convection that is ongoing at the start of the period along a strong front near the MS River. Late this evening, a well-organized squall line was advancing east across AR/east TX toward LA. This activity is handled well by 00z model guidance which surges a squall line into western MS by the start of the day1 period. Earlier thoughts regarding this convective scenario remain. Strongly sheared linear MCS is expected to advance across the central Gulf States during the first half of the period. Environmental shear strongly favors supercells but the primary convective mode should be linear along a strongly forced boundary. Damaging winds are the primary threat with this activity, though embedded circulations could pose some tornado threat. It’s not entirely clear how much pre-frontal discrete convection will develop due to limited heating. Even so, surface dew points rising into the upper 60s should be adequate for surface-based supercells. Given the forecast shear, tornadoes are certainly possible, especially if discrete convection can develop ahead of the squall line.
Timeline/
Storms will move across the region between 4am and 7pm on Saturday.
The HRRR model shows the line falling apart as if moves across parts of Mississippi. That outcome is still TBD, but it supported by multiple other computer weahter models.
Threats
By rank, here are the main concerns…
1. Gusty Wind (wind gusts up to 70mph possible)
2. Heavy Rain (up to 3″ of rain possible)
3. Lightning (storms may produce frequent lightning strikes)
4. Brief tornadoes (quick spin-up tornadoes may occur in storms along the line)
5. Supercells (isolated storms ahead o fthe line capable of producing the above threats in higher amounts)
6. Strong tornadoes (EF-2 or stronger tornadoes are not likely, but also not impossible in this setup)
Notice that wind and rain are at the top, and strong tornadoes are at the bottom. It looks like just about everyone that has the line of storms rolls through will get wind gusts up over 30mph. Some will see gusts to 50mph. Others will see wind gusts up to 70mph.
Everyone will see heavy rain, with some localized flooding possible.
Earlier Discussion
If you missed my facebook chat from earlier, you can catch it here (though, you may want to skip ahead a few minutes as I spent the first few mintues talking about ghosts moving my equipment around).
