Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
839 PM EDT Sat Oct 11 2025
Day 1
Valid 01Z Sun Oct 12 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...
18Z Update...Only a few minor changes were made to the outlook
areas, based on the latest observational and mesoanalysis trends,
along with the latest HREF and RRFS QPF exceedance probabilities.
Hurley
0830Z Excessive Rainfall Discussion...
...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 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
839 PM EDT Sat Oct 11 2025
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...
21Z Excessive Rainfall Discussion Update...
There was enough areal coverage of rainfall to maintain a Slight
Risk area in parts of southern Arizona and New Mexico...although
the overall footprint decreased since the overnight model runs now
that it looks like Raymond (or what remains) will struggle to make
it out of Mexico. The previous outlook only needed some minor
adjustments.
Bann
Previous Excessive Rainfall Discussion...
...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 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
839 PM EDT Sat Oct 11 2025
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...
21Z Excessive Rainfall Discussion Update...
Given an uptick in rainfall amounts in the 18Z deterministic WPC
QPF across portions of New Mexico and eastern Arizona...expanded
the areal coverage of the Slight Risk area a bit. Otherwise...the
run to run consistency resulted in little change to either of the
Marginal risk areas.
Bann
Previous Excessive Rainfall Discussion...
...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
Day 3 threat area:
www.wpc.ncep.noaa.gov/qpf/99epoints.txt
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
307 PM EDT Sat Oct 11 2025
Over the Northeast, the coastal storm and its effects (blustery
winds, high surf, and above normal tides) will pull away from the
coast at the start of the period. Focus will be on the West as the
incoming upper low that will bring in the rain/snow to California
will be underway on Tuesday. A Marginal Risk in the Excessive
Rainfall Outlook is noted for areas between San Francisco and Los
Angeles. Heavy snow is likely in the Sierra above 6500-7000ft. In
addition, another Marginal Risk area exists over New Mexico where
moisture levels remain high.
Into Wednesday, the system will continue southeastward and push
the rain/snow into the Intermountain West, with a continued threat
over New Mexico where another Marginal Risk area is in place. Much
of the West will see at least some rain or snow, with snow levels
lowering as colder air moves in. Temperatures will be well below
normal Tue-Wed (by 10-20 deg) with some slight moderation for the
rest of the week, but still staying cooler than normal.
For the central states, southwesterly flow will increase the
chances of light to modest rain late Tuesday into Wednesday over
the Northern Plains into the Upper Midwest closer to the jet
stream. However, mild and moisture-laden air to the south (central
to southern Plains) will support at least isolated showers and
perhaps some storms ahead of the western/Rockies system. Much of
the Southeast will remain dry and warm through the period with
temperatures well into the 80s and low 90s (South TX).
Fracasso
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
307 PM EDT Sat Oct 11 2025
Over the Northeast, the coastal storm and its effects (blustery
winds, high surf, and above normal tides) will pull away from the
coast at the start of the period. Focus will be on the West as the
incoming upper low that will bring in the rain/snow to California
will be underway on Tuesday. A Marginal Risk in the Excessive
Rainfall Outlook is noted for areas between San Francisco and Los
Angeles. Heavy snow is likely in the Sierra above 6500-7000ft. In
addition, another Marginal Risk area exists over New Mexico where
moisture levels remain high.
Into Wednesday, the system will continue southeastward and push
the rain/snow into the Intermountain West, with a continued threat
over New Mexico where another Marginal Risk area is in place. Much
of the West will see at least some rain or snow, with snow levels
lowering as colder air moves in. Temperatures will be well below
normal Tue-Wed (by 10-20 deg) with some slight moderation for the
rest of the week, but still staying cooler than normal.
For the central states, southwesterly flow will increase the
chances of light to modest rain late Tuesday into Wednesday over
the Northern Plains into the Upper Midwest closer to the jet
stream. However, mild and moisture-laden air to the south (central
to southern Plains) will support at least isolated showers and
perhaps some storms ahead of the western/Rockies system. Much of
the Southeast will remain dry and warm through the period with
temperatures well into the 80s and low 90s (South TX).
Fracasso
