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FOUS30 KWBC 041440
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1040 AM EDT Fri Jul 4 2025

Day 1
Valid 16Z Fri Jul 04 2025 - 12Z Sat Jul 05 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR WEST-CENTRAL
TEXAS...

...16Z Update...

...Central Texas...
A mesoscale convective system stalled over Central Texas this
morning and dropped 9-12+ inches of rain for some areas over the
past 12 hours, which resulted in catastrophic and deadly flash
flooding. This system is expected to persist through the afternoon
while slowly drifting east, with an axis of heavy rain forecast to
orient itself SSW-NNE across Central Texas and drop an additional
5+ inches of rain. Out of the available Hi-res guidance, the HRRR
has been handing this event the best, capturing the magnitude and
position of the highest rainfall well. Any additional rainfall over
areas that were hit this morning will be problematic. The highest
risk area will be generally from Kerr County to Mills County where
the band of heavy rain is expected to set up. Additional flash
flooding is expected and will likely have significant to
potentially catastrophic impacts. To address this evolving threat,
a Moderate Risk area has been introduced.


...Previous Discussion...

...Central Texas...
Ongoing storms associated with the mid-level remains of tropical
cyclone Barry and a plume of anomalous moisture are expected to
continue beyond 12Z this morning, resulting in additional heavy
amounts and the potential for flash flooding. Fueled by PWs
~2 to 2.25 inches (+3 std dev above normal), the consensus of the
hi-res guidance shows slow-moving storms, with heavy rainfall
rates continuing this morning across portions of South-Central
Texas and the Hill Country. A Slight Risk area was introduced for
areas where the HREF is showing high neighborhood probabilities for
additional accumulations over 2 inches. The bulk of this is
expected to fall during the morning into the early afternoon,
before waning and drifting east by this evening.

...Northern/Central Plains to the Upper Midwest...
The overnight guidance continues to show a strong signal for
widespread moderate to heavy amounts associated with training
storms that are expected to develop later today. Increasing
southerly winds ahead of a shortwave trough moving across the
Northern Plains will draw a deep moisture plume up into the region,
with PWs increasing to ~2 inches (~3 std dev above normal). Storms
are expected to develop and train along a slowly-advancing cold
front, supporting heavy accumulations and the potential for flash
flooding. The general consensus of the guidance shows the heaviest
amounts centered across southeastern North Dakota into northern
Minnesota. HREF neighborhood probabilities for amounts over 2
inches are well above 70 percent across much of this region, with
the HREF showing some higher probabilities for amounts over 3
inches are well. Models also show convection developing farther to
the south into the Central Plains. However, the general consensus
indicates these storms will be more progressive - limiting the
threat for widespread heavy amounts and flooding concerns.

...Florida...
Deep moisture pooling along the remnants of a stalled frontal
boundary and an upper low will continue to support an environment
conducive to heavy rainfall. Similar to yesterday, the models show
a weak wave dropping into the western Gulf, helping to focus heavy
amounts along the Sun Coast. Also similar to yesterday, the HREF is
showing high neighborhood probabilities for amounts over 3 inches.
However, much of the hi-res guidance has been underperforming
across this area, with the coverage of heavy amounts yesterday far
less impressive than what was forecast. Therefore, lacking
confidence in the models, opted not to upgrade to a Slight Risk at
this point, but will continue to reevaluate.

...Northern Intermountain West/Rockies...
A well-defined shortwave trough and modest moisture anomalies are
expected to support widespread showers and storms across the
region. Some of these storms may produce locally heavy amounts,
with the HREF showing high neighborhood probabilities for
accumulations over an inch within the Marginal Risk area. This may
produce localized flooding concerns, especially over areas of
complex terrain and recent burn scars.

Pereira

Day 2
Valid 12Z Sat Jul 05 2025 - 12Z Sun Jul 06 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE NORTHERN PLAINS, UPPER MIDWEST, TEXAS, FLORIDA, AND THE
SOUTHEAST COAST...

...Northern High Plains...
A well-defined shortwave trough moving across the Northwest on Day
1, will move across the northern Rockies into the High Plains,
where it will interact with moisture pooling along a boundary
banked along the high terrain. Strong mid-to-upper level forcing
along with modest moisture anomalies will support storm
development, with some potential for locally heavy amounts as these
storms move east across eastern Montana and the western Dakotas.

...Upper Midwest...
A deep moisture plume (PWs ~2 inches) will continue to advance east
along with a well-defined shortwave trough across the Upper
Midwest/Great Lakes, supporting heavy rain across the region. Some
training may continue from Day 1 into Day 2, raising the threat for
additional heavy accumulations and flash flooding. However,
confidence in its placement is less than that in the previous day.
And with some of the guidance indicating a more progressive system,
and/or the focus for heavy amounts moving across Lake Superior into
Canada, opted to maintain just a Marginal Risk area for now.

...Central Texas...
While the models are far from in agreement, some including the
ECMWF, the Canadian, and the UKMET indicate that lingering moisture
and mid level energy will produce additional storms and potentially
heavy amounts across portions of central Texas, including those
areas being currently impacted by heavy rains.

...Southeast...
The model consensus shows an area of low pressure becoming better
organized and moving north along the Southeast Coast. As it does,
heavy rainfall may become more of a concern across coastal sections
of the Carolinas. Meanwhile, deep moisture remaining across
Florida will support another day of showers and storms capable of
producing heavy amounts.

Pereira

Day 3
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 CENTRAL AND SOUTHERN HIGH PLAINS AND ACROSS THE
EASTERN CAROLINAS...

...Great Lakes to the Central and Southern Plains...
A shortwave trough over the Great Lakes will weaken and move east,
however deep moisture along its trailing boundary may support
showers and storms from the Great Lakes back through the mid
Mississippi Valley into the Plains. Mid level energy moving out
into the Central Plains may help support storm development and a
greater threat for heavier amounts across portions of the High
Plains into Kansas and Nebraska.

...Carolinas...
The models present a good deal of spread regarding the development
and track of a low now forming east of the Florida coast.
Regardless of development, heavy rain can be expected for at least
portions of the Carolinas this period. As the forecast becomes
clearer, adjustments in the placement and category of the ERO will
likely be necessary. But for now, given the uncertainty, opted to
maintain just a Marginal Risk covering much of the eastern
Carolinas.

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