FOUS30 KWBC 110832
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
432 AM EDT Sat Oct 11 2025

Day 1
Valid 12Z Sat Oct 11 2025 - 12Z Sun Oct 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
FOUR CORNERS STATES AS WELL AS FOR PORTIONS OF COASTAL NORTH
CAROLINA AND SOUTHEASTERN VIRGINIA...

...Southwest to the Northern Rockies and High Plains...

An amplified upper trough will move east from the West Coast to 
the Rockies. Deep southwesterly flow ahead of the trough will 
continue to transport tropical moisture and energy north from the
Southwest/Four Corners Region early in the period. The GFS is 
showing PW anomalies of 4-5 std dev above normal from the Southwest
into the central Rockies this morning, with anomalies increasing 
further to the north into the northern Rockies/High Plains as the 
trough continues to shift east later today.

Moisture and energy associated with the remnants of Tropical
Cyclone Priscilla will continue to lift north from the
Southwest/Four Corners region, but residual moisture left in its
wake will maintain significant anomalies from the Southwest up 
through Four Corners before a front associated with the upper 
trough brings in drier air through the Four Corners by tonight.
However, PW anomalies are expected to remain notably high across 
southeastern Arizona and southwestern New Mexico, where moisture 
moving out ahead of Tropical Cyclone Raymond is expected to spread 
into the region. 

Overall, not much change to the previous outlook areas, with a
Slight Risk extending from the Southwest through the Four Corners
into the central Rockies, where moisture and energy associated with
Priscilla are expected to support widespread precipitation,
producing locally heavy amounts early in the period. Both the HREF
and RRFS show high probabilities for accumulations exceeding an 
inch covering much of the western Colorado ranges, with high 
neighborhood probabilities for amounts exceeding 2 inches centered 
over the San Juans. Further to the south, hi-res guidance show 
showers and storms firing later today, with repeating development 
across portions of southern Arizona and New Mexico. Both the HREF 
and RRFS show high probabilities for amounts over 2 inches centered
along the Mogollon Rim into southeastern Arizona and portions of 
southwestern New Mexico.

Lastly, across the northern Rockies and High Plains, strong ascent
afforded in part by favorable upper jet forcing, interacting with
the previously noted anomalous moisture plume spreading north, may
be sufficient to produce some locally heavy amounts, with isolated
runoff concerns from eastern Idaho and western Wyoming into parts 
of southwestern and central Montana today.

...Coastal Carolinas and Southeastern Virginia...

An area of low pressure now organizing east of Florida will
continue to deepen and track north this morning, before slowing as
it reaches the Carolina coast later today. Strong easterly winds 
north of the center will draw deep moisture inland, with heavy rain
likely to impact coastal North Carolina this evening into the 
overnight before reaching into southeastern Virginia during the 
overnight as well. Models continue to show the potential for 
several inches along the North Carolina coast, but with a tight 
gradient further inland. Maintained a Slight Risk across coastal 
North Carolina into southeastern Virginia, where in addition to 
heavy rain, coastal flooding generated by the strong onshore winds 
is likely to compound runoff concerns. 

Pereira


Day 2
Valid 12Z Sun Oct 12 2025 - 12Z Mon Oct 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN ARIZONA AND NEW MEXICO...

...Southern Arizona to West Texas...

Anomalous moisture will remain in place, fortified by moisture 
associated with the remnants of Tropical Cyclone Raymond pooling 
along the frontal boundary settling into the area. This moisture 
interacting with increasing ascent afforded by mid level energy and
favorable upper jet forcing will support additional showers and 
storms, with the potential for heavy rain and flash flooding. 
Maintained a Slight Risk, but reduced its footprint across the 
region. Overall, the 00Z models have trended lighter across the 
U.S., with the heaviest amounts focused south of the U.S.-Mex 
border. There still remains a decent signal for at least locally 
heavy amounts to develop, so a Slight Risk was maintained across 
portions of southeastern Arizona into far southwestern New Mexico, 
with a Marginal Risk extending farther east into West Texas.

...Mid Atlantic Coast to Southern New England...

Models continue to differ on the details on how the low pressure
along the East Coast will evolve this period. The general consensus
of the models shows an area of low pressure lingering and weakening
over the Mid Atlantic, as a second low begins to develop along the
Northeast Coast as its associated frontal system interacts with a 
northern stream low becoming cutoff over the Northeast. The models 
however differ on the amplitude and track of the system, lowering 
confidence in the precipitation forecast over the Northeast. 
Regardless of development, easterly winds will spread at least some
moderate to locally heavy amounts from the northern Mid Atlantic 
coast northward into southern New England, with coastal flooding 
remaining a compounding concern. Given the uncertainty, with 
several models keeping heavy amounts offshore, opted to remove the 
Slight Risk for now. However, should the 00Z ECMWF be the start of 
a trend toward a more amplified/westerly solution, a Slight Risk 
may be reintroduced.

Pereira


Day 3
Valid 12Z Mon Oct 13 2025 - 12Z Tue Oct 14 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF
SOUTHEASTERN ARIZONA, SOUTHWESTERN NEW MEXICO, AND SOUTHERN
COLORADO...

...Southwest to the Central Rockies...

Backing flow ahead of a deep low dropping south into northern
California will draw lingering anomalous moisture over the 
Southwest back to the north into the central Rockies. This moisture
interacting with favorable mid to upper level forcing will generate
additional showers and storms, with guidance indicating an elevated
chance for locally heavy amounts and flash flooding concerns over
portions of southeastern Arizona, southwestern New Mexico, and the
San Juan Mountains.

...Northern and Central California....

Models are in generally good agreement showing an anonymously deep
upper developing and dropping south along the West Coast from the 
Pacific Northwest to Northern California this period. Moisture with
the system will be relatively modest initially, but enough to 
raise moisture anomalies to over a std dev above normal along its 
axis of strong onshore flow. This along with strong forcing may be 
sufficient to produce locally heavy amounts, with isolated runoff 
concerns, especially in the upslope regions of the coastal ranges 
and the Sierra foothills.

....Northeast...

Plenty of questions remain as to how the low developing along the
Northeast coast will continue to evolve, but most agree on at least
a localized threat for heavy rain centered along the southeastern 
New England coast continuing into the period.

Pereira
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