AWUS01 KWNH 101336
FFGMPD
LAZ000-TXZ000-101835-

Mesoscale Precipitation Discussion 0987
NWS Weather Prediction Center College Park MD
936 AM EDT Tue Sep 10 2024

Areas affected...TX and southwestern LA coast

Concerning...Heavy rainfall...Flash flooding possible

Valid 101335Z - 101835Z

Summary...Isolated flash flooding will be possible along TX
coastal locations into far southwestern LA through 18Z. Rainfall
rates of 1 to 2+ inches may allow for spotty 2-4" totals.

Discussion...13Z radar imagery from KBRO showed the northwestern
edge of higher reflectivity associated with the inner core of T.S.
Francine located 80 miles southeast of South Padre Island, TX.
There was a gap in rainfall northwest of Francine, between the
inner core and a fairly persistent rain band impacting southern
Kenedy into Willacy counties with MRMS-derived rainfall rates of 1
to 2+ in/hr. MRMS rainfall estimates are believed to be reliable
given matching values of MRMS to local gauge data in/near
Brownsville earlier between 09-12Z.

A combination of 12Z soundings, GPS and SPC mesoanalysis data
showed precipitable water values along the LA and TX coasts to be
between 2.1 and 2.8 inches, and MLCAPE of up to 250 J/kg, except
along the far southern TX coast where MLCAPE is estimated to be
between 500-1000 J/kg. However, available instability was limited
to coastal locations, falling off rapidly with inland extent.
While Francine is currently moving slowly toward the north, an
expected turn toward the northeast along with an increase in
forward speed through 18Z is forecast by the 09Z NHC advisory.
This motion will likely allow outer rainbands to move ashore the
middle and upper TX coasts into far southwestern LA by early
afternoon but instability should remain limited for coastal
locations through 18Z, except for the upper TX coast where values
of 500-1000 J/kg are forecast by recent RAP guidance. Low level
convergence will allow for brief training potential along the
entire TX coastline with rainfall rates of 1 to locally 2+ inches
per hour and localized 2-4 inch totals. Flash flooding will be
possible but should remain very isolated with some locations not
seeing much if any rainfall through 18Z.

Otto

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!7Y5-kZLYwP3v9dMX9SHzUhpNllSG6OXHW3gIRAeoorBVYsTgqSsRQ47TWPn7NF9XNxYk=
Md2lkReCmz3WN0B_8VziOXw$  for graphic product...

ATTN...WFO...BRO...CRP...HGX...LCH...

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

LAT...LON   30119324 29879313 29599320 29459356 29199410=20
            28619510 28209607 27689669 27179687 25889691=20
            25899765 27069780 28219736 28879653 29709494=20
            29979397=20

=3D =3D =3D
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