A severe weather event is expected to unfold this afternoon, tonight and tomorrow.
This Afternoon and Tonight
Discrete cells should fire up between 5 PM and 6 PM CDT. Coverage should then increase for the remainder of the evening going into the overnight.
A line of storms is still likely to develop with a cold front along/east of I-35 and sweep east. However, weakening still seems probable tomorrow morning due to lack of instability and/or it outrunning the cold front.
The Storm Prediction Center (SPC) has not really made any changes to the categorical risk zones (see figure 2).
Very large hail remains the primary threat. Damaging wind gusts are also likely. A few tornadoes also still can’t be ruled out.
Tomorrow
The above mentioned cold front will east.
Dew points surging into the 65 – 70 degree F range will help fuel development of widespread thunderstorms by late morning/early afternoon tomorrow over Louisiana.
During the afternoon, activity will move into Mississippi, and then into Alabama and the Florida Panhandle by the evening/overnight hours.
With a strong low-level jet and CAPE (instability) values generally between 500 – 1500 j/Kg, we should see scattered to numerous strong/severe storms.
An intense, well organized squall line will likely form along the front. Bulk shear values up to 60 – 65 knots will be supportive of supercells ahead of the main convective line.
Enhanced risk area for tomorrow has been expanded. Now includes all of east Louisiana, much of Mississippi, west Alabama, and the far western FL Panhandle. pic.twitter.com/HndF65Y12p
— Gulf Coast Storm Center (@GCSCWX) April 17, 2019
The SPC has expanded the enhanced risk area. They have also hatched a significant risk area in their probabilistic outlook (see figure 1). The greater risk for severe weather will be within these two zones. Note that both are still subject to change.
Guidance is in agreement on high storm relative helicity (SRH) values (see figure 4), signaling a threat for tornadoes with any supercells.
The SPC notes: “potential exists for a strong tornado or two.” There could also be tornadoes within the squall line.
On top of the tornado threat, significant damaging wind gusts up to 70 – 75 mph will also be a concern, mainly with the squall. Some instances of hail will be possible too. But, at least as of now, tornadoes and damaging winds look to be the main issue.
Prepare
Be sure to stay weather aware today and tomorrow.
Continue to monitor the forecast. Be sure to have a reliable way to receive watch/warning info. DON’T really on tornado sirens. If a warning is issued for your location, know your safe space and go to it. It is also critical that you know what county you are in.
