Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
450 AM EDT Wed Aug 26 2026
Day 2
Valid 12Z Thu Aug 27 2026 - 12Z Fri Aug 28 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER MISSISSIPPI VALLEY AND THE NORTHEAST...

...Northeast...

A Slight Risk upgrade was introduced over the Northeast with this
update. An upper-level trough will continue to slowly inch its way
eastward, enhancing upper divergence aloft, especially upwind over
southern NJ and southeast Pennsylvania. A healthy influx of
moisture is forecast to flow onshore from the Gulf stream to the
south, with around ~20kts 850mb southerly flow expected. PWATs
around 1.75-2" will support heavy rainfall which will be
continuously fueled by the aforementioned low-level flow. Latest
global model runs are in agreement as to the general area of the
QPF core in the northeast. The 00Z run of the RRFS appears to also
converge toward a northern Mid-Atlantic to Northeast solution,
albeit much more bullishly compared to the global solutions. Given
this, the Slight area was introduced, and the availability of more
CAMs guidance should result in refinement/fine tuning of the risk
area.

...Southeast and Gulf Coast...

An upper-level shortwave over the eastern portion of the country
will continue pushing southward, with a surface cold front moving
southeastward. Upon arrival to the Gulf Coast, it will stall over
Louisiana and southern Mississippi for the next few days. While
approaching and eventually residing near the coast, the boundary
will contend with ample moisture moving northward from the Gulf,
yielding multiple rounds of storms with the potential for heavy
rainfall. Flood prone urban areas such as New Orleans, Baton Rouge,
Mobile, and some of the more interior areas of Mississippi dealing
with the latest of multiple days of heavy rains will all support
widely scattered instances of flash flooding. Rainfall and
thunderstorms will bring heavy rainfall to Alabama and Georgia as
well, and the previously mentioned trough encounters a similarly
moist airmass being pushed northeastward in the lower levels. This
will support several rounds of storms in the form of multiple lines
across Georgia and parts of South Carolina. The storms moving
northeastward could allow for some training as the cold front moves
through, and could bring widely scattered instances of flash
flooding.

...Southwest...

As similarly stated in previous outlooks, a very gradual eastward
progression of the upper ridge across the Southwest should allow
for a shifting of the heaviest precipitation to the east out of
Utah and more into the central Plains. The ridge should largely
preclude much organization from the storms, so the Marginal
continues to focus on the areas where either terrain or prior
rainfall could locally increases the risk of flash flooding.

Blanco-Alcala/Wegman


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