Severe WX December 16-17 2019 Severe Weather Outbreak

[Equus]

Day one is an enhanced. If trends continue, fully expect 5% at least to be pulled east.

 

[Kory]

Short range rapid refresh mesoscale guidance continues to show multiple supercells in confluence bands lining up in the warm sector in Louisiana and Mississippi going tornadic early this afternoon. We're starting to see the signature of those take shape over Louisiana right now.

 

[JayF]

The more I look at the Supercell Composite and the Cape/Shear models for today, the more I believe Louisiana, Mississippi and central Alabama are the places to watch for significant severe weather. North Alabama could see small tornadoes but I am not seeing anything significant there.

Still need to stay weather aware. They dynamics can change depending if we get any sun in N. AL.

 

[TornadoFan]

Tornado watch coming. Mentions possibility of strong tornadoes.

Storm Prediction Center Mesoscale Discussion 2202

Severe weather, tornado, thunderstorm, fire weather, storm report, tornado watch, severe thunderstorm watch, mesoscale discussion, convective outlook products from the Storm Prediction Center.

www.spc.noaa.gov

 

[warneagle]

There are a few relatively discrete cells already popping in LA. They have that kind of “stretched” appearance though.

 

[Kory]

There are a few relatively discrete cells already popping in LA. They have that kind of “stretched” appearance though.

A few are broadly rotating too. As the LLJ ramps up, so will the mesocyclones.

 

[Equus]

Given the MCD, wonder if we get a hatch on the next outlook.

 

[Kory]

Given the MCD, wonder if we get a hatch on the next outlook.

Given some of the shear profiles, these will be long tracking supercells. Probably cyclical in nature.

 

[Taylor Campbell]

Given the MCD, wonder if we get a hatch on the next outlook.

They say this in the current outlook discussion.

Given sustained warm-sector supercells with little storm-scale
interference, such as progged by the sometimes overly aggressive
HRRR, such an environment can support significant/EF2+ tornadoes.
At this time, however, amount and longevity of relatively discrete
cells in the warm sector are still uncertain, especially given some
EML-driven capping, and flow aloft being largely parallel to the
primary corridor of forcing near the front. A hatched/significant
area may need to be added in an upcoming outlook if mesoscale
diagnostic trends and 12Z numerical guidance increase confidence in
multiple warm-sector supercells.

 

[Kory]

We've got two tornado warnings in Louisiana now.

 

[Equus]

Aaand radar confirmed tornado already NE Shreveport with rapidly developing couplets. It's 10am. That's not a pleasant sign

 

[JayF]

We've got two tornado warnings in Louisiana now.

The tornado warning for N LA is observed.

 

[South AL Wx]

Moderate risk out now for portions of LA/MS.

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[warneagle]

Well this escalated quickly.

 

[Equus]

Hello there MDT. Yeesh

 

[Kory]

Lines up perfectly where the UH streaks are being forecasted to be most intense. Looks pretty spot on for all guidance I've seen.

 

[warneagle]

Wouldn’t be surprised if the one near Elizabeth produced soon too. Very impressive radar presentation.

 

[TornadoFan]

Classic hook on the storm near Elizabeth.

 

[Equus]

Honestly pretty bold for the SPC in the cold season but can't blame at all. Also 45% wind contour while we're at it

 

[South AL Wx]

From the SPC discussion:

Given potential for sustained warm-sector supercells, such as
progged by the HRRR, HRRR-P and WRF-ARW, such an environment will
support a risk for multiple significant tornadoes.

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