Graphic for MPD #0024

Mesoscale Precipitation Discussion 0024
NWS Weather Prediction Center College Park MD
1031 PM EST Tue Jan 23 2024

Areas affected...south through east Texas, northern and central
Louisiana

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

Valid 240331Z - 240931Z

Summary...Areas of flash flooding are ongoing beneath an ongoing
mesoscale convective complex extending from central Texas through
northern Louisiana.  Flash flooding will remain likely through
09-10Z as the complex makes very slow eastward progress tonight.

Discussion...An elongated MCS continues, extending from southwest
of CLL/College Station, Texas to MLU/Monroe, Louisiana this
evening.  This axis of deep convection has been slow to
move/propagate eastward, with deep southwesterly steering flow
aloft, low-level boundaries oriented parallel to that flow, and
500-1500 J/kg SBCAPE located over the undisturbed warm sector just
southeast of the storms.  Because of the slow movement of the
storms and only localized upscale propagation/right movement of
individual segments within the broader MCS, areas of 2-5 inch
rainfall totals have occurred since 21Z, resulting in occasional
impacts from flash flooding.

It is a bit concerning that deep convection has also been
developing upstream of this axis (from Cotulla to east of San
Antonio).  That activity is occurring in response to embedded
shortwaves amid deep, cyclonically curved southwesterly flow
emanating from northern Mexican provinces.  That convection is
expected to continue northeastward toward the current MCS,
allowing for continued areas of heavy rainfall amid already
saturated soils.  Areas of 2-4 inch rainfall amounts (locally
higher) are expected through 09-10Z and should result in a
continued flash flood risk through the night.

Over time, the expanding convective coverage should result in
increased forward-propagation and right movement off the current
axis of heavier rainfall, although this process should take
several hours to materialize.  The increased propagation and
additional convection out over the warm sector will allow for the
flash flood risk to gradually shift eastward as well.  Heavier
rain rates will likely be confined to Texas portions of the MCS
where the greatest surface-based instability resides.

Cook

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

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

LAT...LON   32779282 32459198 31779198 30689250 29319522
            28109737 27839861 28949887 29839787 30599697
            31619601 32469445
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Last Updated: 1031 PM EST Tue Jan 23 2024