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FOUS30 KWBC 051556
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1156 AM EDT Sat Jul 5 2025

Day 1
Valid 16Z Sat Jul 05 2025 - 12Z Sun Jul 06 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR A PORTION OF
CENTRAL TEXAS AS WELL AS THE COASTAL CAROLINAS...

...16Z Update...

...Central Texas...

A higher end Slight is in effect for a portion of central Texas
from San Antonio north. An ongoing MCS that has been responsible
for the catastrophic flooding further west will remain active
through the day today, as excessive amounts of Gulf moisture
continue to stream northward into the thunderstorms. There remain a
few cells producing multiple inch per hour rainfall rates,
especially just east of San Antonio with this update. Over the
next few hours with daytime heating, the storms are likely to
reintensify, and track westward with time. There remains some
potential that strong storms with very heavy rainfall may move over
areas already hard hit with heavy rains, though that`s not
explicitly forecast in the guidance, likely because those areas
have been worked over. Nonetheless it goes without saying that
should heavy rain move over hard-hit areas, then additional
flooding impacts are very likely.

There also remains some potential for refiring of storms in the
predawn hours of Sunday in some of the areas of the Slight, based
on some of the guidance, so despite likely waning of thunderstorm
activity after sunset, new storms could pose a threat.

Should strong thunderstorms reform over hard hit areas, a Special
update with an upgrade to a Moderate Risk may be needed.

...Carolinas/T.S. Chantal...

Much of the high resolution guidance on Chantal have shifted the
focus for the heaviest rain through 7am Sunday a bit to the south
into coastal South Carolina. Given the very slow movement of the
storm, a higher end Slight is in effect from southwest of Myrtle
Beach through Wilmington. Much of the rainfall that may result in
flash flooding in those coastal communities will fall after sunset
tonight through the overnight. In the meantime, expect the outer
bands of Chantal to impact the coast with briefly heavy rain and
gusty winds.

...Midwest...

Trimmed the western end of the inherited Marginal behind where the
rain has already fallen, but otherwise very few changes expected as
all looks on track in this area.

Wegman

...Previous Discussion...

...Central Texas...
Concerns remain for additional heavy rain and flooding across
portions of South-Central Texas and the Hill Country. Overnight
guidance shows another surge of deeper moisture pushing north
across central Texas, with PWs at or above 2 inches bisecting the
state today. Many of the hi-res members show scattered storms
developing along this axis this afternoon. Fortunately, most depict
these storms initiating outside of those areas hardest hit by
yesterday`s rains. However, there is some indication that storms
may drift west back into those areas and there is some overlap
between those inundated areas and where the new HREF is showing
high neighborhood probabilities for additional accumulations
exceeding 3 inches.

...Southeast...
Tropical Depression Three is expected to intensify some as it
moves northwest and is expected to make landfall along the central
South Carolina coast near the end of the period. The potential for
efficient, heavy rainfall producing bands will increase as onshore
flow ahead of system pushes PWs above 2.25 inches along portions of
the South and North Carolina coasts. This moisture along with deep,
warm cloud layers will support periods of heavy rain, with locally
heavy amounts. The forecast track and general consensus of the
guidance shows the greatest threat for heavy amounts centering from
the Grand Strand toward Cape Fear. HREF neighborhood probabilities
for amounts over 3 inches are highest in this region. A small
targeted Slight Risk was placed over this area, with the greatest
threat for flash flooding expected to focus over urbanized and
poor drainage areas.

Further to the south, a trailing boundary and axis of deep moisture
will support showers and storms with locally heavy amounts across
central Florida.

...Northern High Plains...
A well-defined shortwave trough will move from the Northwest into
the northern High Plains. The associated large-scale forcing,
along with increasing moisture, supported by low level
southeasterly flow, will encourage shower and thunderstorm
development. PWs are expected to increase to ~1 to 1.25 inches (1
to 1.5 std dev above normal), with the deeper moisture and greater
anomalies centering from southeastern Montana into the Black Hills
region. While a widespread heavy rainfall event is not expected,
heavy rainfall rates and some potential for redeveloping storms may
produce locally heavy amounts (greater than an inch) and isolated
runoff concerns.

...Upper Midwest to the lower Missouri Valley...
A shortwave trough will continue to advance east out of the
northern Plains and across the Upper Midwest/Great Lakes. This will
push the associated cold front further south and east, with low
level southeasterly flow supporting a deep moisture pool (PWs ~2
inches). This will support widespread shower and thunderstorm
development across the region. While some southwest to northeast
training may elevate the potential for heavy amounts and flooding
concerns, storms are expected to be generally progressive. One area
where a potential upgrade may be necessary is across portions of
central and eastern Iowa, where some of the hi-res guidance shows
an initial round of storms developing along a prefrontal trough,
followed by a second round along the front. HREF neighborhood
probabilities indicate that totals in excess of 2 inches are
likely, with some potential amounts over 3 inches across this area.

Pereira

Day 2
Valid 12Z Sun Jul 06 2025 - 12Z Mon Jul 07 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE GREAT
LAKES TO THE MID MISSISSIPPI VALLEY/OZARKS, PORTIONS OF THE
CENTRAL AND SOUTHERN HIGH PLAINS, AND ACROSS THE CENTRAL AND
EASTERN CAROLINAS...

...Central Texas...
While PWs are expected to come down, moisture will remain
sufficient for storm development and the potential for additional
locally heavy amounts. The overnight model consensus places the
greater threat further west than the greater Day 1 threat, however
there remains some overlap with this and the recently inundated
areas in the Hill Country. Coverage and forecast confidence are
not high enough to warrant a Slight Risk, but will continue to
monitor this area for potential upgrades.

...Carolinas...
Tropical Cyclone Three is expected to move inland and quickly
begin to weaken. May continue to see additional heavy rainfall
worthy of an upgrade to a Slight Risk, especially across portions
of the South Carolina Pee Dee Region and southeastern North
Carolina. However, the overall threat for heavy rain is expected to
decrease during the period.

...Central to the Southern High Plains...
Low level upslope will support increasing moisture, which along
with ample instability, and mid-level forcing, will support shower
and thunderstorm development. There is some indication that
organized storm development, producing locally heavy amounts will
occur across portions of the central High Plains, which may result
in isolated flooding concerns. Further to the south, storm
development is expected to be less organized, but may occur across
the more sensitive portions of eastern New Mexico.

...Great Lakes to the Mid Mississippi Valley/Ozark Region...
A cold front and its associated pool of deeper moisture will
continue to push farther south and east, focusing showers and
thunderstorms and the threat for locally heavy amounts and isolated
flooding concerns.

Pereira


Day 3
Valid 12Z Mon Jul 07 2025 - 12Z Tue Jul 08 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE UPPER
MIDWEST TO THE SOUTHWEST, THE NORTHEAST TO THE OZARK REGION,
PORTIONS OF CENTRAL TEXAS, AND EASTERN NORTH CAROLINA TO
SOUTHEASTERN VIRGINIA...

...Eastern North Carolina and Southeastern Virginia...
The threat for heavy rainfall will continue to decrease, however
some additional heavy amounts are possible as Tropical Cyclone
Three is expected to dissipate over eastern North Carolina.

...Northeast to the Ozark Region...
The previously noted cold front will push across the Northeast
while lingering back across the Ohio into the mid Mississippi
Valley. Overnight models indicate a greater threat for heavy
amounts will focus along with some right-entrance region upper jet
forcing and greater moisture anomalies across northern New England.
However, sufficient moisture is expected to remain in place ahead
of the boundary to support at least localized heavy amounts and an
isolated flooding threat further southeast along and ahead of the
boundary.

...Northern Plains and Upper Midwest...
Models show a well-defined shortwave moving across the region this
period. With plenty of differences in the details, models indicate
some potential for organized heavy rains developing ahead of this
wave as it interacts with an influx of deeper moisture.

...Central Plains to the Southern High Plains/Rockies...
Similar to the previous day, the models are presenting a notable
signal for showers and storms, supported by moist low level inflow,
to develop over High Plains, with some potential for locally heavy
amounts to occur as they move east.

Meanwhile, the coverage of storms and potential flooding concerns
is expected to expand across New Mexico as the monsoon pattern
builds, with moisture increasing across the region.

Pereira

Day 1 threat area: https://www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Day 2 threat area: https://www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Day 3 threat area: https://www.wpc.ncep.noaa.gov/qpf/99epoints.txt