Mesoscale Discussion 2273
NWS Storm Prediction Center Norman OK
1156 AM CST Mon Nov 20 2023
Areas affected…East/Southeast TX…Much of LA
Concerning…Severe potential…Tornado Watch likely
Valid 201756Z – 202000Z
Probability of Watch Issuance…95 percent
SUMMARY…A Tornado Watch is expected this afternoon from
east/southeast Texas into much of Louisiana, where the potential for
tornadoes, some of which could be strong, exists.
DISCUSSION…Recent surface analysis places a low over south-central
OK, with a cold front extending southward through central TX and
then more southwestward into the TX Hill Country. A warm front also
extends southeastward from this low to SHV, stretching more
east-southeastward from there across central LA into southwest MS.
Showers and isolated thunderstorms are ongoing within the warm
sector, supported by ample low-level moisture and warm-air advection
within the warm conveyor. Several attempts at more sustained
thunderstorm development have occurred farther west along the cold
front, but none have been successful thus far.
A somewhat complex convective scenario is expected to play out from
east/southeast TX into central LA this afternoon. Favorable
low-level moisture will continue to advect northward ahead of the
approaching cold front (and parent upper-level trough), contributing
to air mass destabilization. Southerly/southwesterly low-level flow
will increase this afternoon as well, strengthening low-level shear
within an environment that already has favorable deep-layer shear.
The result will be an environment supportive of supercells whenever
updrafts mature. This maturation may initially be stunted by limited
buoyancy, but continued low-level moisture advection should allow
for this limitation to be overcome by the late afternoon. A corridor
of moderate buoyancy is expected from east-central TX into central
Supercells capable of all severe hazards, including tornadoes are
anticipated. Shear profiles suggest the potential for a strong
tornado exists, particularly near the warm front, if a more discrete
mode can be maintained. Given this potential, a Tornado Watch will
be needed across portions of the area this afternoon.
…Please see www.spc.noaa.gov for graphic product…
LAT…LON 30949625 31959576 32609508 32889401 32939325 32789224
32379180 31789184 30949224 30359283 30149348 30119441