AWUS01 KWNH 250604
FFGMPD
TXZ000-251200-

Mesoscale Precipitation Discussion 1188
NWS Weather Prediction Center College Park MD
103 AM EST Wed Dec 25 2024

Areas affected...Southeast TX, including Middle and Upper TX Coast

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

Valid 250600Z - 251200Z

Summary...Flash flooding remains possible overnight with localized
rainfall rates of 1-3"/hr and additional short-term totals as high
as 3-5" (favored in the vicinity of Victoria and around the Middle
TX Coast).

Discussion...A digging shortwave trough is driving a complex of
thunderstorms over portions of Southeast TX, gradually moving
towards the Middle and Upper TX Coast. Peak rainfall rates have
generally ranged from 1-2"/hr, though occasionally have peaked
between 2-3"/hr along the southern end of the complex (per MRMS
estimates). The mesoscale environment is characterized by ML CAPE
of 500-1750 J/kg, precipitable water values of 1.2-1.4 inches
(near the 90th percentile for late December, per CRP sounding
climatology), and deep layer (0-6 km shear) of 25-50 kts (with
both instability and shear maximized in the vicinity of Victoria).

Going forward, the expectation is for the complex of thunderstorms
to remain active until near dawn, particularly along the southern
portions of the complex. Not only is this the best environment for
discrete convection, but supercells have already favored this area
with bunkers right motions supporting slow storm motions (10-15
kts). With both the strongest and slowest convection near the
Middle TX Coast, the highest localized totals of 3-5" are possible
here (per 00z HREF 40-km probabilities for 3" exceedance of
30-50%, as well as more recent runs of the HRRR indicating totals
near 5"). Farther north (including the greater Houston metro
area), lower instability and a stronger cold pool should support
weaker and faster storm motions, generally limiting additional
totals to the 1-2" range.

Churchill

...Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6yI9FnMjRfliJHO1AgUChmY7PJv3qFXeb6DtnVXuVPConpX-9354XnRHjm7cJEPIGE1y=
n-z-dHGCYjoZH5TvTpfGOs0$  for graphic product...

ATTN...WFO...CRP...EWX...HGX...LCH...

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

LAT...LON   30979476 30979413 30629412 29899440 29399466=20
            28959495 28439573 27929684 28799819 29419813=20
            29939697 30449603 30769531=20

=3D =3D =3D
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