Graphic for MPD #0029

Mesoscale Precipitation Discussion 0029
NWS Weather Prediction Center College Park MD
415 PM EST Wed Jan 24 2024

Areas affected...South-Central to Southeast TX...Southwest LA

Concerning...Heavy rainfall...Flash flooding likely

Valid 242115Z - 250315Z

SUMMARY...Renewed rounds of heavy showers and thunderstorms will
continue into the evening hours which will facilitate additional
areas of flash flooding given locally very sensitive/saturated
soil conditions.

DISCUSSION...GOES-E satellite imagery in conjunction with dual-pol
radar is showing an uptick in the coverage of showers and
thunderstorms across areas of south-central to southeast TX
including an increase in rainfall rate intensity. The activity is
being strongly facilitated by the arrival of additional shortwave
energy crossing the region from the Rio Grande Valley which is
interacting with the sustained pooling and local resurgence of
stronger moisture transport and instability out ahead of a frontal
zone draped across the region.

Cloud top temperatures have been cooling along and just inland of
the middle TX coast and including areas generally south and east
of Victoria and toward Palacios, and this general area is where
the corridor of heaviest rainfall rates have been occurring over
the last couple of hours.

PWs across the southeast TX coastal plain remain on the order of
1.5 to 1.75 inches, and MUCAPE values are locally exceeding 1000
J/kg down toward the middle TX coast. This coupled with rather
strong shear profiles will continue to help support renewed rounds
of convection over the next several hours which include an
expansion across areas of southeast TX and into southwest LA.

The latest hires CAM guidance suggests stronger jet-forcing
arriving heading into the evening hours and already the satellite
imagery shows a notably divergent flow structure aloft crossing
the Rio Grande Valley and lifting northeastward toward southeast
TX. The hires models have been tending to struggle much of the day
with the redeveloping rounds of convection, and some of this has
been connected to the poor handling of a long-lived and
convectively reinforced outflow boundary which extends from the
middle TX coast east out over the northwest Gulf of Mexico.

Given the latest HRRR guidance and overall convective trends, the
expectation is that convection should tend to grow a bit more
upscale, with rainfall rates closer to the coast that may reach
1.5"/hour. Some additional rainfall totals going through the early
evening hours may reach as much as 2 to 4 inches, and especially
where any cell-training occurs with these renewed convective
rounds.

Given the already very sensitive/saturated soil conditions, these
additional heavy rains will exacerbate ongoing runoff problems and
likely foster new areas of flash flooding.

Orrison

ATTN...WFO...CRP...EWX...FWD...HGX...LCH...SHV...

ATTN...RFC...LMRFC...WGRFC...NWC...

LAT...LON   32039397 31619321 30959278 30199271 29679297
            29569398 28889520 28539599 28349657 28469715
            28939747 29619736 30539626 31949523
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Last Updated: 415 PM EST Wed Jan 24 2024