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Severe WX Severe Weather Threat 3/14-3/16

FWIW, new outlook with statement:

"DANGEROUS TORNADO OUTBREAK IS ONGOING AND EXPECTED TO CONTINUE THIS
EVENING OVER THE SOUTHEAST. THE MAIN CHANGE FOR THE 20Z OUTLOOK WAS
TO EXPAND THE CATEGORICAL HIGH RISK A BIT OVER SOUTHWESTERN AL AND
SOUTHERN MS, AND TRIM OUT THE SEVERE AREAS WEST. A SQUADRON OF
INTENSE TORNADIC SUPERCELLS WILL CONTINUE EAST/NORTHEAST OVER
EASTERN MS, AND MUCH OF WESTERN AL THIS AFTERNOON AND INTO THE
EVENING. THE STRONGEST LOW-LEVEL THETA-E ADVECTION IS OCCURRING
ACROSS SOUTHEASTERN MS AND WEST/SOUTHWESTERN AL. STRONG ASCENT AND
INTENSE LOW-LEVEL SHEAR FROM A 60-70 KT LOW-LEVEL JET SHOULD
CONTINUE TO FOCUS A NEARLY OPTIMAL SUPERCELL/TORNADO ENVIRONMENT
OVER THIS AREA THROUGH THIS EVENING.

UPSCALE GROWTH INTO ONE OR MORE BOWING LINE SEGMENTS WILL BE
POSSIBLE LATE THIS EVENING OVER EASTERN AL AND WESTERN GA. STRONG
SHEAR WILL CONTINUE THE RISK FOR TORNADOES ALONG WITH DAMAGING
GUSTS.

OVER NORTHERN AL AND SOUTHERN TN, WIDESPREAD CONVECTION HAS RESULTED
IN A MESSY STORM MODE WITH EMBEDDED SUPERCELL STRUCTURES. A STRONG
MESO LOW (994 MB) WILL CONTINUE NORTHEAST ALONG THE MS RIVER VALLEY
SUPPORTING IMPRESSIVE LOW-LEVEL SHEAR (0-1 KM SRH OF 250-500 M2/S2)
DESPITE THE LESS FAVORABLE THERMODYNAMICS. TORNADOES (SOME STRONG)
AND NUMEROUS DAMAGING WIND GUSTS ARE POSSIBLE WITH THE EMBEDDED
SUPERCELLS AND BOWING SEGMENTS AS A MORE LINEAR STORM MODE SHOULD BEGIN TO EMERGE THROUGH THIS EVENING."1000000641.png
 
20Z D1 unchanged except for pruning western edges of the risk.
1742069361790.png
 
The first frame of the HRRR run shows immense CAPE then, when simulated, it almost completely disappears within 2 hours. It has been doing the same thing the last 3 or 4 runs, even though the starting cape has gone up with each run. Basically, it's showing decreasing CAPE within an hour or two, but then the following runs are showing INCREASED CAPE, so it's failing to verify even an hour or two ahead. It's almost seems like it's getting confused with the amount of energy the system is pulling up from the gulf and can't correct itself. I hope I'm wrong though, and this is actually what we see.

1742068838686.png
1742068863122.gif
 
Grand Poo Bah said:
The first frame of the HRRR run shows immense CAPE then, when simulated, it almost completely disappears within 2 hours. It has been doing the same thing the last 3 or 4 runs, even though the starting cape has gone up with each run. Basically, it's showing decreasing CAPE within an hour or two, but then the following runs are showing INCREASED CAPE, so it's failing to verify even an hour or two ahead. It's almost seems like it's getting confused with the amount of energy the system is pulling up from the gulf and can't correct itself. I hope I'm wrong though, and this is actually what we see.

View attachment 36211
View attachment 36212
Click to expand...
There will be diurnal waning of instability, but a mixture of the LLJ, moisture return and the fact that it actually got sunny and warm over much of the region will mean that CAPE of >500 j/kg will be maintained across the area well after dark.
 
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