451
AWUS01 KWNH 161402
FFGMPD
TXZ000-161900-

Mesoscale Precipitation Discussion 0457
NWS Weather Prediction Center College Park MD
1001 AM EDT Mon Jun 16 2025

Areas affected...Coastal South Texas...

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

Valid 161400Z - 161900Z

SUMMARY...Small MCC will continue to slowly drift southward with
2-3"/hr rates and localized totals up to 5"+ resulting in
continued flash flooding concerns through early afternoon.

DISCUSSION...A small cluster of thunderstorms continues to grow
upscale into a well formed/concentric Mesoscale Convective Complex
across the lower TX coast.  GOES-E WV suite shows the primarily
forcing shortwave is between the two larger scale ridges west and
east of it with a clear break in the mid-level westerlies to its
north.  Right entrance to a 25kt outflow jet to the south along
the coast has been providing solid outflow aloft to maintain the
MCV/shortwave especially given the mid-level latent heat release
with this tropical-like complex.  In the lower levels, the
southerly Western Gulf LLJ has been providing solid flux
convergence to the WSW to ENE outflow boundary across Corpus
Christi Bay that has also taken on a N-S confluent orientation as
far south as South Padre Island into NE Cameron county.
Additionally, the mid-level outflow along the SW flank of the
complex has been expanding a banding-like feature into N Kenedy
county fairly orthogonal to the LLJ further enhancing convective
complex.   Given total PWats over 2.25" and 20-25kt of orthogonal
inflow, the hourly rates of 2-3" are common and broadening in
coverage.

Very slow south-southwestward propagation is expected over the
coming hours.  Upstream instability remains more than sufficient
with MLCAPEs already well over 2000 J/kg.  Given the favorable
upper-level environment for outflow, would expect this convective
complex to maintain/expand southward along the coast with broad
2-4" totals with localized 5-6" probable.  Eventually, the western
Gulf LLJ/WAA maximum will continue to slide north-northeast into
the Upper Texas coast, likely to reduce some low-level convergence
closer to the beaches, but still will provide solid flux to the
complex.  Additionally, this complex is also moving through very
low population and very favorable soil conditions for
infiltration, the shear amount in time will likely continue to
produce flash flooding conditions through the noon-time hours into
early afternoon.

Gallina

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...BRO...CRP...

ATTN...RFC...FWR...NWC...

LAT...LON   27599797 27599754 27379730 26869729 26139712
            26129762 26439818 26899826 27319820