Mesoscale Precipitation Discussion 0142
NWS Weather Prediction Center College Park MD
1157 PM EDT Tue Apr 09 2024

Areas affected...southeastern TX into south-central LA and western
MS

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

Valid 100356Z - 100915Z

Summary...Training of heavy rain is expected to impact portions of
southeastern TX into south-central LA through 09Z. Localized
rainfall rates near/over 3 in/hr are expected and 6-hr totals of 3
to over 6 inches will be possible. Some significant flash flooding
may occur.

Discussion...Regional radar and infrared satellite imagery at
0330Z showed an MCS advancing over the Lower MS Valley with
upstream training of thunderstorms along its southwestern flank in
southeastern TX. Observed rainfall rates within the axis of SW to
NE training in southeastern TX have been observed near 3 in/hr and
2 to 4 inches have already occurred over Hardin and Tyler counties
within the past 3 hours. Thunderstorms over southeastern TX into
western LA were forming along a low level convergence axis in the
925-550 mb layer, with steering flow parallel to the convergence
axis, supporting training. SPC mesoanalysis data from 03Z showed
ample MLCAPE of 1500 to 2500+ J/kg over southeastern TX with
little to no inhibition.

925-850 mb winds are forecast by the RAP to maintain a southerly
fetch with 25-35 kt speeds slowly translating east into western LA
over the next few hours, but with the convergence axis remaining
in roughly the same place for at least the next 2-4 hours. A
concern for significant rainfall totals and possibly significant
flash flooding comes from expected upstream development, already
underway with a forward propagating cell just west of College
Station and additional development in the vicinity of San Antonio.
The eastward movement of a mid/upper level trough over West Texas
is expected to allow for increasing thunderstorm development
within the instability pool over southeastern TX near a stationary
front analyzed west to east across central/southeastern TX into
LA.

While the axis of ongoing training along the Sabine River may
begin to shift east with time, additional upstream development is
likely to support the development of training from west to east
near the stationary front from portions of southeastern TX into
south-central LA. Rainfall rates of 2 to near 3 in/hr will be
possible at times and 6-hr totals through 09Z are expected to
climb into the 3 to 6 inch range, with localized totals higher
than 6 inches possible. These high rainfall totals are expected to
result in scattered to numerous areas of flash flooding, some of
which could be tied associated with considerable impacts.

Otto

ATTN...WFO...HGX...JAN...LCH...LIX...SHV...

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

LAT...LON   32929142 32719065 32359058 31649080 30679185
            30119266 29729348 29349521 30339573 31039453
            32419374