Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
807 PM EDT Fri Jul 26 2024
Day 2
Valid 12Z Sat Jul 27 2024 - 12Z Sun Jul 28 2024

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE
MIDDLE TEXAS COAST...

...20Z Update...

In coordination with HGX/Houston, TX and CRP/Corpus Christi, TX
forecast offices, a Slight Risk upgrade was introduced with this
update. Continued onshore southerly flow of deep tropical moisture
off the Gulf will bring yet another day of occasionally heavy rains
to much of the Middle Texas Coast on Saturday. This area has been
hard hit with heavy rain over the past few days, resulting in well
below normal FFGs for much of the coast from Corpus Christi to
Galveston. Fortunately, the rainfall expected on Saturday should be
much less organized as compared with this morning and previous
days. However, given the saturated soils along the coast and deep
tropical moisture allowing any convection that forms to be capable
of very heavy rain rates, there still is a slight risk of flash
flooding, whereas this pattern would likely only favor a Marginal
if the area were much drier.

Elsewhere, only modest adjustments were made to the expansive
Marginal Risks across the middle of the country, Southeast, and
West. As is typical for both July and previous days' anywhere in
the Marginal risks for the Mississippi Valley and Southeast will
have storms capable of organizing or producing local outflow
boundaries that may initiate additional convection, so isolated
instances of multi-inch rainfall totals are quite possible given
the plentiful moisture that remains across this region.

Wegman

...Previous Discussion...

...Southern and Southeastern United States...
The 26/00Z suite of numerical guidance showed deeper moisture
getting drawn north and eastward from the Texas coast towards the
western part of the Tennessee Valley given persistent south to
southeasterly flow on the east side of an upper level
trough/closed low. With mid-level height rising from the western
Great Lakes to eastern Tennessee Valley, opted tom limit the
eastern extent of the Marginal. Elsewhere...enough instability and
sufficiently deep moisture will be in place for almost any storms
that develop to produce isolated flash flooding due to slow moving
downpours.

...Southwest United States...
Confidence remains below average in the potential and placement of
flash flooding across the West...with the areal coverage shrunk yet
again from the previous issuance. Given the terrain and lingering
deep moisture in much of the West, it's going to be really tough
to completely eliminate the flash flooding potential.

Bann

Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt