Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
833 PM EDT Fri Oct 2 2026
Day 2
Valid 12Z Sat Oct 03 2026 - 12Z Sun Oct 04 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL
GULF COAST AND SOUTHERN COASTAL TEXAS...

..20z Update..

Southern Coastal Texas: A Slight Risk ERO was introduced across
southern coastal Texas from areas north of Corpus Christi
southwards to Brownsville. Synoptically, a slow moving frontal
boundary will be present across the region and focus surface
convergence to enhance thunderstorm coverage. Moreover, a mid-level
wave traversing the Gulf will increase moisture transport and
frictional convergence along the southern Texas coastline that may produce
locally heavy precipitation. Some of the precipitation could
overlap with areas that have received heavy rainfall over the past
few days and have saturated soils, which was also taken into
consideration for the introduction of a Slight Risk. Overall, QPF
amounts of 2-4 inches are reasonable, particularly close to the
coast line and locally higher amounts may be realized as indicated
by the latest HREF 24 hr QPF 50-70% probabilities of exceeding 5
inches.

Central Gulf Coast: No major changes were made to the forecast
expectation of tropical moisture to surge into the central Gulf
Coast and result in locally heavy rainfall and scattered instances
of flash flooding. A mid-level wave moving northward across the
Gulf will increase moisture transport from coastal Louisiana to
the Florida Panhandle and advect anomalously high PWATS over 2.5
inches that will fuel tropical rains. The latest QPF forecast has
3-5 inches with localized maximum of 5-7 inches for the 24 hour
period on Saturday with a tight gradient of the highest QPF along
and south of I-10. Flash flooding impacts will be greater near the
coastline and mainly realized over locations that see the higher
end rainfall totals. In terms of changes, the Slight Risk was
trimmed closer to the central Gulf Coast coastline and the Slight
Risk was removed from the eastern Texas coastline as models showed
the highest QPF remaining offshore.

Carolinas: An approaching cold front and a surge of PWATS above 2
inches will focus a swath of heavier precipitation across South
Carolina into eastern North Carolina. The forecast calls for an
average of 2-3 inches of rain with a maxima of 3-5 inches possible
as indicated by CAMS. The greatest confidence for the higher QPF
amounts are over southeastern North Carolina where there are 50-70%
probabilities for 24 hr QPF exceeding 5 inches. However, these
same areas are exceptionally dry and have 3 hour flash flood
guidance exceedance values nearing 5 inches. Instability is also
forecast to be around 1000 J/Kg or less in the Carolinas, which
will also limit the coverage of 2+ inch hourly rainfall rates. All
said, this a higher end Marginal Risk with some scattered instances
of flash flooding possible, but the underlying hydrology of the
area precluded a Slight Risk at the time.

Wilder

...Previous Discussion...

Broad southerly flow off the Gulf will pump increasing amounts of
deep tropical moisture northward into the central Gulf Coast on
Saturday. PWATs will continue to climb from previous days, likely
exceeding 2.5 inches across portions of the central Gulf coast.
Extensive cloud cover due to the extreme amounts of atmospheric
moisture and the early October sun should generally limit
instability except along the immediate coast, where the greatest
threat lies. Due to numerous urban areas along the coast, the
Slight was largely maintained. While it's uncertain which areas
will see the most rainfall, everywhere from Houston through
Pensacola have some threat for prolonged heavy rainfall on
Saturday. The Slight was expanded west to include the Houston
metro, in coordination with HGX/Houston, TX forecast office. Even
there the greatest threats will be along the coast, with the lower
threats north and west of Houston. A similar scenario is in place
for New Orleans, Biloxi, Mobile, and Pensacola. For those latter
cities, their locations along the coast will make them more prone
to potential heavy rainfall Saturday afternoon. The Slight risk
balances the second consecutive day of heavy rain and urban threats
with very high amounts of available moisture against prior dry
soils and very high FFGs due to sandy and flat, swampy areas that
are highly flood-resistant.

Across the Carolinas, a slow southward-moving cold front will run
into the same highly moist air mass. There will likely be an area
of enhanced rainfall, generally stretching from 50 miles or so on
either side of the NC/SC border. Very dry soils going in should
generally preclude all but isolated flash flooding outside of any
urban areas, such as Charlotte and Greenville/Spartanburg. A lack
of instability will also prevent much heavy rain from occurring, in
favor of a long-duration light to moderate rainfall event.

Wegman


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