FOUS30 KWBC 210847
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
447 AM EDT Tue Jul 21 2026

Day 3  Valid 12Z Thu Jul 23 2026 - 12Z Fri Jul 24 2026

...THERE ARE SLIGHT RISKS FOR EXCESSIVE RAINFALL FOR A PORTION OF
THE SOUTHEAST FROM GEORGIA THROUGH THE CAROLINAS AS WELL AS FOR
NORTHEAST KANSAS AND SOUTHEAST NEBRASKA...

...Southeast...

The stalled out front that has remained across the Southeast will
continue to plague the area with very heavy rainfall, as the
continuous stream of Gulf moisture from the Gulf funnels
northeastward along the front. Yet another day of heavy rain is
expected to impact the Carolinas as a result. The front may drift
ever so slightly further south and east which should clear all but
the Hampton Roads area of far southeast Virginia from the heavy
rainfall threat by Thursday, but for much of eastern North
Carolina, much of South Carolina, and portions of northern Georgia,
generally from Atlanta east, the heavy rainfall threat will
continue through Thursday. Once again, potential for very heavy
rainfall totals in many areas as are expected to see heavy rain
from Wednesday could mean further upgrades to the risks may be
needed, especially across eastern North Carolina. Ultimately, where
the heaviest rain falls both today and Wednesday should dictate if
further upgrades will be needed.

...Central Plains...

An MCS is expected to impact a portion of northeast Kansas,
southeast Nebraska and the Kansas City and St. Joseph metros on
Thursday. The heavy rainfall footprint has drifted south and west,
so the Slight Risk has been adjusted accordingly. As with many
MCS's the location of the heaviest rain is likely to continue
shifting with future updates, most likely towards the south, so
stay tuned for further updates. Periods of heavy rain may continue
to impact Wyoming into Colorado as well, where upgrades to a Slight
are also probable, depending on where the heavy rains from
Wednesday overlap with Thursday's forecast.

...Bertha...

Bertha, who may no longer be a tropical cyclone by Thursday, and
likely to be in a weakening state, should continue to keep any
associated rainfall off the coast. The immediate coast remains with
the best chance for seeing anything over an inch of associated
rainfall. FFGs are significantly higher than that in all areas.
Given this, and with very good consistency in this scenario in the
guidance, the inherited Slight and Marginal for a portion of the
Texas and Louisiana Gulf coasts was removed with this update. The
Marginal Risk has been downgraded to under a 5% risk for the upper
Texas Gulf Coast, as well as the Slight for coastal Louisiana
downgraded to a Marginal with this update.

Wegman
 

Day 4 and Day 5  Valid 12Z Fri Jul 24 2026 - 12Z Sun Jul 26 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
LOWER MISSOURI VALLEY AND MID MISSISSIPPI VALLEYS ON DAY 4 AND FOR
PARTS OF SOUTHEAST COAST DAYS 4 AND 5...

...Southeast...
A multi-day rainfall event is expected to continue into the
weekend, with additional heavy rains likely, especially for parts
of southeastern Virginia and the Carolinas. The focus for these
rains will be a slow-moving, moisture-laden front that is forecast
to linger across the region through at least the first half of the
weekend. Southwesterly flow ahead of a shortwave trough moving
through the Ohio/Tennessee valleys will further fortify the already
moisture-rich airmass, with models showing PWs increasing in
excess of 2.25 inches (+2 to 3 sigma). This moisture, along with
pockets of enhanced ascent afforded by mid-level energy, will
support periods of heavy, highly-efficient rainfall. While areas of
heavy rainfall are likely, forecast confidence regarding their
placement remains limited due to continuing model spread with
regards to the placement of the front, which will have impacts on
where the heaviest amounts occur.

...Gulf Coast...
Northeasterly shear and dry air north of the center should keep
much of the heavy rainfall threat associated with T.S. Bertha out
over the open waters. Also, there is some question regarding the
intensity of the system and if it will retain a closed circulation
as it moves from the Louisiana onto the upper Texas coasts early in
the period. However, cannot not rule out an isolated threat for
heavy rainfall and therefore maintained a Marginal Risk for now
from the southwestern Louisiana to the upper Texas coasts on Day 4.

...Lower Missouri-Mid Mississippi to the Tennessee Valleys/Southern
Appalachians...
Ongoing storms associated with pooling moisture along a low-level
boundary and ahead a mid-level shortwave dropping southeast may
continue to support storms and the threat for heavy rains Friday
morning (Day 4) across parts of the lower Missouri Valley. Storms
are expected to wane by late in the morning, but there remains a
model signal for new storms developing farther to the south and
east as additional energy interacts with deepening moisture (PWs
increasing to 2-2.25 inches) that will be supported by
southwesterly low level inflow.

As this energy spills farther south, it may help to organize heavy
rainfall across portions of the Tennessee Valley into the southern
Appalachians, where a Marginal Risk was introduced for Day 5.
Forecast confidence was limited by model spread, however this may
be an area where a targeted upgrade is required in a future update
if confidence increases.

...Southwest/Great Basin/Central and Southern Rockies...
After what is expected to be a downward trend in convective
coverage and potential flash flooding late in the week (Day 4),
moisture anomalies are forecast to increase again on Saturday. This
increasing moisture along with mid level energy moving around the
southwestern periphery of a broad high will help expand afternoon
and evening storm coverage, including the southern Arizona deserts.

Pereira
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