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
406 AM EDT Sun Oct 12 2025
Day 1
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...
...Southwest...
Deep moisture, fortified with the remnants of Tropical Cyclone
Raymond, will remain in place over portions of southern Arizona and
New Mexico. This morning's mesoanalysis shows PWs of 1.25-1.6
inches (3-4 std dev above normal) covering much of region. This
moisture along with increasing large-scale ascent, provided by an
approaching upper trough, will support another day of widespread
showers and storms capable of producing moderate to heavy amounts.
Maintained a Slight Risk covering much of southern Arizona and a
small portion of southwestern New Mexico. Both the HREF and RRFS
neighborhood probabilities indicate locally heavy amounts
exceeding 2 inches are likely within this region, with some
potential for amounts over 3 inches, especially across parts of
southern Arizona.
...Eastern Southern Carolina and Southeastern North Carolina...
The initial low of what is expected to evolve into a two feature
system is forecast to linger along the coast in the vicinity of the
North and South Carolina border today. Deeper moisture will remain
as well, with many of the 00Z models, including the globals,
showing a notable signal for locally heavy amounts developing later
today. While instability will be limited, deep saturation through
the column, and tall, skinny CAPEs are expected to support very
efficient rains, promoting heavy amounts. Both the HREF and RRFS
showing high probabilities for additional amounts over 3 inches
today across parts of the region. These amounts may raise runoff
concerns, especially for those areas where significant rains have
already occurred. Therefore a Marginal Risk was introduced for
areas where the hi-res ensembles indicate the heaviest amounts are
most likely to fall.
...Northern Mid Atlantic to Southern New England Coasts...
North of its parent, a secondary, triple-point low is forecast to
develop near the northern Mid Atlantic coast. There remains some
model uncertainty regarding if and to what degree this low will
become the dominant surface feature. Despite the differences,
there is broad agreement that strong, low level easterly winds, in
combination with strong mid-to-upper level forcing, will support
widespread precipitation from the northern Mid Atlantic coastal
region to central New England, with heavy amounts expected along
the coast. These heavy rains may compound what are likely to be
poor ground conditions attributed to ongoing coastal flooding.
Pereira
Day 1 threat area:
www.wpc.ncep.noaa.gov/qpf/94epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
406 AM EDT Sun Oct 12 2025
Day 2
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...
Lingering deep moisture over southern Arizona and New Mexico will
be drawn north ahead of an upper trough amplifying over California.
This moisture along with the broad-scale ascent afforded by the
upper trough will support one more day of showers and storms across
the Southwest, but this time shifting a bit further east while
extending north across New Mexico into the central Rockies. With
drier air working into southwestern Arizona, the potential for
heavy rain and the threat for flash flooding will become more
limited across that area. However, further to the north and east, a
Slight Risk was maintained along eastern portions of the Mogollon
Rim into southeastern Arizona and southwestern New Mexico. There
remains a notable signal for additional moderate to locally heavy
amounts across that area. Also remaining is a Slight Risk in a
portion of the San Juan Mountains, where models show deep
persistent southerly winds, along with favorable upper forcing,
supporting heavy totals as well.
...Northern and Central California....
Models remain 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 this system will be relatively modest initially, but enough
to raise moisture anomalies to 1-2 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 below the snow line.
....Northeast...
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 spreading north from southern New
England up along the coast to areas perhaps as far north as coastal
Maine. Given the uncertainty, kept the Marginal Risk centered to
the area where the GEFS and ECENS both indicate that amounts
exceeding an inch are most likely.
Pereira
Day 2 threat area:
www.wpc.ncep.noaa.gov/qpf/98epoints.txt
Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
406 AM EDT Sun Oct 12 2025
Day 3
Valid 12Z Tue Oct 14 2025 - 12Z Wed Oct 15 2025
...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS OF
CENTRAL TO SOUTHERN CALIFORNIA, NEW MEXICO, AND WEST TEXAS...
...Central to Southern California...
A deep upper low will continue to dig south early in the period
before turning east across California into the Great Basin this
period. Before turning inland, this system will support an ongoing
threat for heavy precipitation, with the focus shifting south along
with its associated axis of deep onshore flow across Southern
California into the southern Sierra Nevada. A Marginal Risk was
drawn south along the Southern California Transverse Ranges, where
0.75-1 inch PWs interacting with favorable upper jet dynamics and
orographic ascent are expected to support rainfall amounts of 1-2
inches along the favored terrain. These amounts may produce
isolated runoff concerns, especially over vulnerable burn scar
areas. A Marginal Risk was also maintained further to the northeast
along the southern Sierra foothills, where similar amounts are
expected below the snowline.
...New Mexico and West Texas...
As drier air continues to spread east across Arizona into eastern
New Mexico, PWs anomalies will remain high across portions of
central New Mexico and West Texas where strengthening low level
easterly winds will add to the lingering moisture. With the
increase in moisture, the GFS shows PW anomalies remaining over 3
std dev above normal across much of the highlighted areas. This
along with daytime heating will support additional shower and
thunderstorm development, with some potential for locally heavy
amounts and isolated runoff concerns.
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
