Tornado Watch Coming Soon…Could Be PDS Watch

A very bad situation is setting up in the moderate-risk area of Southeast Louisiana, Southern Mississippi, and Southwest Alabama. Multiple tornado warning polygons are in effect now in southern Mississippi and southeastern Louisiana.

A Tornado Debris Signature (TDS) is now in the storms on the Jasper/Newton County line in Mississippi west of Meridian. That storm is about to cross I-20 just east of Newton. It is the lead storm in a phalanx of supercells moving northeast and will be the first into Alabama. It could impact Sumter or Pickens Counties in Alabama before 2:30 p.m.

Mesoscale Discussion 2031
NWS Storm Prediction Center Norman OK
1137 AM CST Wed Dec 14 2022

Areas affected…Southeast LA…Southern MS…Far Southwest AL

Concerning…Tornado Watch 587…

Valid 141737Z – 141930Z

The severe weather threat for Tornado Watch 587 continues.

SUMMARY…Tornado threat is increasing across southeast LA and
southern MS. This threat is expected persist throughout the
afternoon with additional watch issuance by 19Z.

DISCUSSION…Regional radar imagery has shown an increase in shower
activity over the past hour within the warm sector over southeast LA
and southern MS. The air mass within this warm sector is
characterized by temperatures in the mid 70s, dewpoints in the low
70s, and MLCAPE around 1000-1500 J/kg. Strong wind fields are also
in place, with numerous surface observations reporting gusts greater
than 20 kt and regional VAD reporting around 50 kt between 1 and 2
km. Mesoanalysis estimates effective bulk shear greater than 60 kt.
These environmental conditions, combined the discrete nature of the
developing showers, result in a setup very favorable for tornadic
supercells. Recent KJAN radar imagery shows many of these showers
are already rotating, and lightning activity noted within a few.

Expectation is for the tornado threat to continue within this region
throughout the afternoon. Tornado Watch 587 is set to expire at 19Z
and will need to be replaced with another watch across portions of
the region. Given the environmental conditions, PDS wording may be
needed in this replacement watch.

..Mosier/Hart.. 12/14/2022

Category: Alabama's Weather, ALL POSTS, Severe Weather