Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1150 AM EDT Wed Oct 7 2026
Day 3
Valid 12Z Fri Oct 09 2026 - 12Z Sat Oct 10 2026

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR FAR SOUTHERN
ALABAMA AND THE WESTERN FLORIDA PANHANDLE...

The circulation of T.S. Isaias, likely as a hurricane, will
approach the Gulf Coast, make landfall, and move inland across the
Southeast Friday and Friday night. See the latest forecast from the
National Hurricane Center at www.hurricanes.gov on the track
forecast.

Rainfall-wise, increasing southwesterly shear over the storm and an
accelerated forward motion will make the rainfall shield along and
east of the track become increasingly lopsided, leaving a sharp
gradient of rainfall on the west side. With continued eastward
nudges to the track, implying a faster forward motion, the
inherited Day 3/Friday forecast was significantly changed with this
update. The Slight Risk was expanded well to the north, now
including Huntsville, AL and Atlanta. Meanwhile, New Orleans, and
all of Louisiana for that matter, look to dodge this cannon ball.
Thus, the Louisiana Gulf Coast was downgraded to a Marginal, and
will likely to continue to be trimmed with future updates.

A Moderate Risk was introduced with this update for far southern
Alabama, including Mobile, as well as the western Florida
Panhandle. It remains probable with the aforementioned eastward
shifts in the track, that the Moderate may be too far west, and the
Mobile area may be able to be dropped from the Moderate with future
updates. Conversely, the Moderate will likely be expanded north
with future updates to include much of central Alabama and possibly
western Georgia. The Moderate was drawn to focus on the Gulf Coast
for now as this area has been included in all of the guidance for
getting hit with very heavy rainfall associated with the core
eyewall of the storm.

There remains a contingent of guidance that keeps the storm further
west and with a slower forward motion. While this appears to be
increasingly unlikely, to account for this possibility, the
Moderate was limited in its northward extent in case the storm
takes its time making it to the coast.

A faster forward speed may necessitate a much higher flooding
threat with future updates for portions of the highly flood-prone
southern Appalachians. As the center of circulation tracks due
north into the Tennessee and Ohio Valleys, an upslope southeasterly
flow into the western Carolinas and north Georgia could pose a
significant flash flooding threat for that region, though for now
that threat is greatest in the Day 4/Saturday time frame.

Wegman

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt