FOUS30 KWBC 070732
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
232 AM EST Tue Jan 7 2025

Day 1
Valid 12Z Tue Jan 07 2025 - 12Z Wed Jan 08 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Kleebauer

Day 2
Valid 12Z Wed Jan 08 2025 - 12Z Thu Jan 09 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Kleebauer


Day 3
Valid 12Z Thu Jan 09 2025 - 12Z Fri Jan 10 2025

Highly anomalous upper trough pattern across the Western CONUS will
help generate a distinct shortwave ejection evolution that will 
create a litany of issues across TX into the Lower Mississippi 
Valley. Upper low expected to be centered over Sonora the prior
period will open as it advances eastward with a second shortwave
digging around the backside of the mean trough creating a fairly
dynamic setup across the Southern Plains. A strong diffluent axis 
of ascent ahead of the ejecting trough will create a blossoming of
precipitation over TX, spreading eastward as the trough migrates 
through the Lone Star State. Surface low pressure will spawn in-of 
the western Gulf with the low center generally close to the TX 
coastal plain, opening the door for a modest instability gradient 
to align within the immediate TX coast up to southwest LA as the 
pattern progresses. Convective regime will be most prominent along 
the coast where forecast theta_E's will slowly climb just above 
seasonal norms allowing for a focused area of surface instability 
along with the already favorable mid and upper level dynamics. 

A cluster of thunderstorms will likely form over the western Gulf 
within the confines of the surface reflection lending a better 
potential for convection to move inland with a heavy rain footprint
tied to any storm moving onshore. There will be a sharp northern 
extent of how long any convective regime can last as much colder to
the north of the coast will limit surface based instability and 
thwart the opportunity for convection to march inland. As of now,
the forecast MRGL risk inherited from D4 was relatively maintained,
although the northern periphery was trimmed back given the
lackluster instability fields and relatively progressive storm
motion on the northern fringe of the best instability coupled with
ascent. The most favorable locations for rates that could generate
enough support for flash flooding potential is still relegated to
the immediate Gulf coast with a small buffer further inland if any
cells can motion past the immediate coastal plain and affect some
of the urban areas extending from CRP up through HOU and LCH. 

Kleebauer 

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