Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1153 AM EDT Sat Oct 3 2026
Day 1
Valid 16Z Sat Oct 03 2026 - 12Z Sun Oct 04 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL
GULF COAST, THE LOWER TEXAS COAST, AND EASTERN NORTH CAROLINA...

...Central Gulf Coast...

16Z Update: Little change necessary for the SLGT risk located
across the Central Gulf coast as the latest 12z CAMs and associated
HREF remain confident in their presentation of locally 4-6+" of
rainfall through the period with a majority of the rainfall
occurring with the approach of weak wave out of the eastern Gulf
later this evening. HREF neighborhood probabilities for >5" remain
elevated (50-80%) across the immediate coastal areas of southern
MS/AL with the eastern extent right over the far western FL
Panhandle. Some of the deterministic outputs from the CAMs are
quite robust with 6+ inches of rain within that immediate coastal
plain thanks to the greatest instability source co-located with the
immediate Gulf waters. The area along I-10 between Biloxi to Mobile
Bay continues to be the most noteworthy area for the higher probs
for >5", a signal that has been prevalent now for multiple runs of
the hi-res guidance. This lends credence to the local threat of
flash flooding and the continuation of the high-end SLGT risk
located over southeast LA into the western FL Panhandle.

Kleebauer

..Previous Discussion..

A tropical wave moving across the Gulf will funnel record to near
record amounts of atmospheric moisture into much of the Gulf Coast
on Saturday. A 15-25 kt southerly flow into the coast at 850 mb
will support numerous showers and thunderstorms associated with the
wave moving into the central Gulf Coast both today and tonight.
PWATs will be at or above 2.5 inches for many areas. Extensive
cloud cover and the October sun should limit instability
considerably with any reasonable distance from the coast. Thus, any
convection that impacts the coast is unlikely to be able to travel
too far inland without significant weakening. Thus, the Slight
highlighting much of the coast remains unchanged. A higher-end
Slight Risk was added with this update from New Orleans through
much of the western Florida Panhandle. They were primarily
included due to urban impacts and the sheer volume of water
expected, as the coast can expect 3-6 inches of rain today, with
locally higher amounts. Despite very high FFGs and dry soils in
this area, this amount of rainfall may overcome that, especially in
urban areas to result in widely scattered instances of flash
flooding.

Wegman

...Lower Texas Coast...

16Z Update: No changes to the previous SLGT risk were necessary
with this forecast update as the latest hi-res guidance continues
to hint at elevated convective threat along the immediate TX coast
from CRP down to BRO and points just inland. Greatest signal
continues to be within that zone with the maxima for both rainfall
outputs and subsequent HREF probabilities noting the King Range
area between the metro areas as the primary area of concern. A
pretty solid HREF EAS signal for at least 2" exists right along
that immediate coastal area just north of South Padre Island,
correlated with the best frictional convergence regime likely
materializing later in the period. Surface analysis depicts a
surface trough off the TX coast into the western Gulf which would
indicate a prevailing easterly flow moving into the coastal plain.
PWATs between 2.1-2.3" and generally formidable low to mid-level
instability max situated across South TX should be enough to garner
local rates upwards of 2-3"/hr in the stronger cell cores that move
ashore. Given all of the above, felt this was more than enough to
warrant a continuation of the SLGT risk with little deviation from
the previous forecast(s).

Kleebauer

..Previous Discussion..

The Slight risk remains in place along the coast of Deep South
Texas as well. Onshore northeasterly flow of the same deep tropical
moisture impacting areas further north and east may impact some
urban areas such as Brownsville. As this portion of the Lower Texas
Coast is roughly perpendicular to the mean flow, expect the onshore
push to allow convection to try to move a few miles inland before
dissipating. No changes were made to the area included in the
Slight Risk with this update.

Wegman

...Eastern North Carolina...

The combination of an approaching front and deep layer moisture
presence across eastern NC will generate a period of enhanced low-
level convergence and heavy rain prospects over areas west of the
Pamlico Sound, impacting some of the more notable population
centers just inland of the coast. Recent trends within the
HREF/REFS mean QPF and associated probability fields indicate
enough of a signal to warrant a targeted SLGT risk for areas of
eastern NC with a centroid focused near New Bern and surrounds.
PWATs between the 90-99th percentile continue to plague the eastern
Carolina's and this setup is no different. Anticipate an increase
in convergence between 925-700mb by late-afternoon and evening as
the cold front to the north slowly sags southward into the
vicinity and taps into the modest instability pool residing in the
region. Light mean winds ahead of the front will keep general storm
motions on the slower side with a potential for cell training after
initiation, something prevalent within the latest CAMs as most of
the guidance indicates thunderstorm genesis with little forward
propagation over the course of their life cycle. A "bullseye" of
>80% probabilities for at least 3" exists over that area northwest
of the Morehead City to Wilmington, NC line based off both the 12z
HREF and REFS depictions. After further coordination with the
local MHX/RAH/ILM office, a targeted SLGT risk was added over the
aforementioned area to account for the threat of locally heavy
rainfall with localized amounts between 3-6" possible in the
hardest hit locations.

Kleebauer


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt