Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
358 PM EDT Tue Sep 22 2026

Valid 00Z Wed Sep 23 2026 - 00Z Fri Sep 25 2026

...Significant Heavy Rainfall/Flooding Threat across New Mexico and the
Southern High Plains through Thursday...

...Heavy Rainfall/Flooding Threat across portions of the Ohio Valley,
Mid-Atlantic, and Central/Southern Appalachians through Wednesday...


A upper-level low/trough will dig into the Southwest and interact with
both the Pacific and Gulf moisture, leading to showers and thunderstorms
across portions of the Four Corners and the Southern/Central
Plains/Rockies. The combination of deep tropical moisture, sufficient
instability, and upper-level forcing will lead to high rainfall rates and
excessive rainfall across portions of the Four Corners and western Texas
tonight. Additionally, WPC maintains a Moderate Risk (at least 40% chance)
of excessive rainfall for southern New Mexico, while a broader area of
Slight Risk (at least 15% chance) covers much of New Mexico. The flash
flooding threat is expected to increase on Wednesday, as the primary
shortwave energy lifts northward through New Mexico. Therefore, the
Marginal and Slight Risk for excessive rainfall will expand into the
Central Plains, while a broad area of Moderate Risk will encompass much of
eastern New Mexico. The southwest moisture will gradually transport
northeastward along a slow-moving boundary, bringing showers and
thunderstorms across the Northern/Central Plains into the Upper Midwest by
late Wednesday into Thursday.

Furthermore, a upper-level troughing over the Great Lakes will gradually
shift eastward toward the Mid-Atlantic and Northeast, while the frontal
boundary will settle southward across the Southern Plains into the
Southeast, Ohio Valley, and Mid-Atlantic. A developing coastal low
offshore will help maintain low-level moisture ahead of the slow-moving
frontal boundary, supporting period of showers and thunderstorms from
portions of the Ohio Valley/Mid-Atlantic into the Appalachians and
Southeast. Pockets of elevated instability may develop along the frontal
boundary, leading to severe thunderstorm concerns across the Southeast.
Additionally, slow storm motions and efficient warm moisture will lead to
locally high rainfall rates within the strongest storms, leading to flash
flooding concerns over portions of the Ohio Valley/Mid-Atlantic and
Southeast.

By Wednesday, the boundary over the Mid-Atlantic and Ohio Valley will move
further south, but shortwave troughs will reinforce another round of
showers and thunderstorms across the area. This will lead to another day
of flash flooding concerns over the Mid-Atlantic and Ohio Valley,
especially over areas where soil remains saturated from previous rainfall.
Further south, a moist and unstable airmass will persist across southern
Florida leading to scattered to numerous showers and thunderstorms, with
locally heavy downpours possible through Thursday.

Temperature-wise, a strong surface high will bring colder than average
temperatures across the northern/central Plains into the Mid-Atlantic and
Northeast behind the frontal boundary, while the southern Plains into the
Southeast will remain warm and humid.

Kebede/Oudit


Graphics available at
https://www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Tue Sep 22 2026

Valid 12Z Fri Sep 25 2026 - 12Z Tue Sep 29 2026


...Impactful coastal storm meanders near the Mid-Atlantic and
Northeast
late week/weekend...


...Overview...

An upper low will stall atop the Mid-Atlantic and Northeast late
week into the weekend, supporting a meandering coastal surface low.
This pattern will lead to strong/gusty onshore winds for multiple
days, leading to coastal flooding, rip currents, high surf, and
potential beach erosion. Meanwhile, an upper ridge persisting in
the south-central U.S. will promote warm temperatures, while a
couple of upper troughs bring rounds of precipitation to parts of
the northwestern and north-central U.S. through the period.


...Guidance/Predictability Assessment...

Models continue to have a decent handle on the overall large scale
pattern through most of the medium range period, though some
uncertainty remains with smaller scale details. Case in point,
there is still a fair amount of spread with coastal low development
in the western Atlantic late week into the weekend underneath a
stalling upper low. The EC and especially the UKMET develop the low
farther south in the Atlantic Friday-Saturday, compared with most
other guidance sources which are farther north and east. The EC
continues to depict a track that reaches near Long Island or the
Jersey Shore by Sunday, while the farther northeast
GFS/AIGFS/CMC/ICON track the low just off the coast of New England.
The EC-AIFS, which was a reasonable middle ground in the previous
forecast, looks more like the EC for its 12Z run. By Monday-Tuesday
the low should be weaker but with remaining questions on when it
pulls away and from where. Given there is still ample spread
between two distinct camps, questions remain with respect to
sensible weather impacts like wind speed/direction and how much
rain falls onshore vs. offshore.

Elsewhere, guidance shows good consensus on the upper ridge in the
south-central U.S., though varying positions of weak fronts and
precipitation potential cause uncertainties in the temperatures.
The ridge looks to extend north and traverse the Midwest/Great
Lakes Friday and over the weekend, contributing to the blocky
pattern as it stretches into southeast Canada north of the Atlantic
upper low. Meanwhile a couple of trough axes will track across the
northwestern to north-central U.S. with typical spread in their
timing and depth. Guidance generally shows one crossing the Pacific
Northwest at the start of the period Friday, tracking across the
northern tier and lifting into central Canada on Sunday. Then an
upstream trough is forecast to move into the West Coast Sunday and
continue tracking east. By Monday into Tuesday models show varying
degrees of stream separation that affects the trough's timing.

Meanwhile, Hurricane Polo in the eastern Pacific has rapidly
intensified into a category 5 hurricane today, with continued
monitoring for downstream impacts later in the period. However,
despite Polo still having some model spread in its track, the
number of models/ensemble members depicting a curve into Baja
California are rapidly decreasing. A more suppressed track would
ultimately limit the amount of moisture that could be drawn
northward into the Southwest as a result.

The WPC forecast used a deterministic and AI model blend early in
the forecast period, then incorporated more ensemble means and
increased the weighting of said means to 50 percent by Days 6-7 to
mitigate the individual model differences in the details of the
pattern.


...Weather/Hazards Highlights...

The meandering surface low in the western Atlantic will lead to
broad onshore flow across the Mid-Atlantic and Northeast for
multiple days. This persistent pattern could lead to coastal
flooding and beach erosion concerns, especially when combined with
high astronomical tides. Exact placement of the surface low from
day to day and thus any heavy rain is more uncertain. The latest
forecast continues to offer support that coastal New England may
see heavy rainfall on Friday into the weekend. However, stay tuned
for forecast updates, as small shifts in the low track would lead
to significant forecast shifts in rainfall amounts. See WPC's Key
Messages for this coastal low for further information.

Pacific moisture is forecast to advect around the western side of
the south-central U.S. upper ridge and lead to some rain across
parts of the central U.S. on Friday. If/where additional rain falls
in New Mexico, there could be flooding concerns after the forecast
heavy rainfall event in the short range causes very wet antecedent
conditions. Meanwhile farther east and northeast into the Plains,
moderate to locally heavy rainfall may be possible, but on less
sensitive ground. Rain chances persist in the Upper/Middle
Mississippi Valley into Saturday. Meanwhile, upper troughing will
bring precipitation to the Pacific Northwest and northern Rockies,
including higher elevation snow chances, on Friday. Scattered
showers and thunderstorms are again possible in parts of the
Plains/Mississippi Valley on Sunday, but a more widespread rainy
pattern with potentially heavier amounts is possible Monday into
Tuesday as Pacific and Gulf moisture combine and stream into the
central U.S. ahead of troughing in the West.

Temperatures are forecast to remain cooler than average by 5-10
degrees in the Mid-Atlantic and Northeast into the weekend
underneath the upper low, and highs will generally be in the 60s.
On the other hand, broad upper ridging over the south-central U.S.
could maintain highs in the 90s for the southern Plains and Lower
Mississippi Valley. Cooler than normal temperatures are likely in
the Northwest given troughing aloft, which should push into the
northern Rockies/High Plains after a warmer than average period
into Friday.


Tate/Miller


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
456 AM EDT Tue Sep 22 2026

Valid 00Z Wed 23 Sep 2026 - 00Z Wed 30 Sep 2026

...Heavy rain and flooding potential with T.D. 15-E remnants...

Above average moisture along with broad, weak energy aloft will
support scattered showers which contain locally heavy
rainfall...especially in windward/mauka areas under moderate
trades which strengthen to strong trades during the latter part of
the week.

Convection with what had been Tropical Depression 15E continued to
move west-northwestward across the Pacific and was several
hundred miles south of the Hawaiian islands as of late Monday
evening. This system will be increasing chances of organized
showers and thunderstorms and associated flooding during the next
several days. The areal extent of flooding and any concern for
wind-related hazard will depend upon the amount of
strengthening/reorganization occurs as the convection moves into
more favorable environmental conditions.

Multiple deterministic ECMWF runs and the EC ensemble spread some
degree of heavy rain and strong winds across much of the state,
while the recent GFS re-curves a closed surface low westward to
the south of the Big Island...limiting the impacts mainly to that
island.

As a result...heavy to excessive rainfall is possible and
flooding will be a concern, at least for the Big Island but
possibly across other islands as well while the concern for strong
winds looks more confined to the southern islands. Stay tuned for
forecast updates on the details. The higher moisture values look
to clear out next weekend and early next week.

Bann

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
835 PM EDT Tue Sep 22 2026
Day 1
Valid 01Z Wed Sep 23 2026 - 12Z Wed Sep 23 2026

..THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF SOUTHERN NEW MEXICO...

...New Mexico and West Texas...

Current radar and satellite composite indicate a turbulent evening
on tap for much of New Mexico with an eastern extension into west
Texas. Shortwave analyzed over Chihuahua will lift northward
through the course of the overnight with increasing ascent and
convergence across southern NM and along the Southern Rockies into
the Sacramento Mountains as prevailing southeasterly flow allows
for focused low-level orographic ascent within the terrain over NM.
Heavy rain has plagued the region over the course of the last 6
hours with a continuation expected overnight as multi-model
consensus, including all CAMs have targeted a large area from far
west TX, including the El Paso metro, to points north and west of
the city center as the focus for significant rainfall and flash
flood prospects. PWATs remain elevated to a degree that PWAT
anomalies based on the recent mesoanalysis and RAOB's from KEPZ and
KABQ pushing well over the 90th percentile as of 18z with a
likelihood of PWATs come the 00z sounding depicting closer to the
upper threshold of the climatological max when assessing the latest
RAP mesoanalysis output.

This setup is likely to provide several flash flood warnings with a
heightened risk of considerable to potentially catastrophic tags
due to the propensity of run off in the deserts and complex terrain
across NM. 00z HRRR remains very bullish on local totals between
2-4", additional located over south-central NM and the Sacramento
Mountain areas, a signal typically coinciding with major flash
flood capabilities and increasing hydrologic concerns as we move
into Wednesday morning. A high-end MDT risk remains forecast for
the area west and northwest of El Paso in NM with a broad MDT
encompassing much of the state given the nature of the heavy
precip. Little deviation from previous forecast for all risks
given the consistency in guidance and ground truth playing out as
modeled.

...Ohio Valley and Mid-Atlantic...

Heavy rain prospects continue across portions of the Carolina
Piedmont into the Midlands of SC with a small ribbon of convection
lingering along the slow advancing backdoor front over eastern NC.
Models are in flux with the specific location of heavy rainfall,
but assessment of the latest radar to CAMs trends signals the
HRRR/RRFS are doing the best job at handling the current evolution
with weight given more towards these CAMs than other guidance. The
positioning and coverage of the convection makes sense synoptically
as the airmass along and south of the wedging cold front is much
more buoyant and capable of maintaining stronger convective cores
that could produce flash flood concerns. Some elevated convection
is capable of isolated flash flooding into NC and VA within
urbanized zones, but the threat is dwindling as the night
progresses. This led to the MRGL and SLGT being cut back over those
areas with a maintenance over the Central and Southern Appalachian
front into the SC Piedmont and southwestern NC due to the greater
instability maxima. Localized amounts of 2-4" are plausible in the
SLGT risk area in those more impacted locations, but signal still
leans towards isolated to widely scattered flash flooding
prospects, a step downward in potential compared to earlier this
afternoon.

...South Florida...

A Marginal Risk has been maintained for portions of South Florida
as PWATs remain elevated supporting heavy rainfall rates and a
localized urban flash flood risk lingering into the first part of
the evening before waning after midnight.

Kleebauer


Day 1 threat area: www.wpc.ncep.noaa.gov/qpf/94epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
835 PM EDT Tue Sep 22 2026
Day 2
Valid 12Z Wed Sep 23 2026 - 12Z Thu Sep 24 2026

..THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF CENTRAL AND EASTERN NEW MEXICO...

...New Mexico and West Texas...
The heavy rainfall threat established on day 1 will be ongoing and
continue and peak over NM on day 2 as large scale forcing gets
even stronger. A well defined mid level shortwave is forecast to
lift northward across the state, accompanied by robust upper level
divergence and the likely development of a surface low. PW values
will remain near record levels for this time of year, with an
anomalously deep moisture profile.

With such strong forcing and widespread moisture in place, the
primary limiting factor for heavy convective rates will be the
extent of cloud cover and its impact on destabilization. While
widespread clouds are a concern, daytime heating should allow at
least the eastern edge of the rainfall shield to sufficiently
destabilize, aided by broad easterly upslope flow. Thus while some
areas may see predominately stratiform rain, a concentrated swath
of intense convective rainfall remains likely.

The most recent guidance still points toward totals of 2 to 4
inches during the 24-hr period, potentially higher up to 5 inches.
This is likely to result in scattered to numerous instances of
flash flooding, some of which could be life-threatening and
significant. This would be most likely across sensitive terrain,
urban areas, and burn scars. The inherited ERO risk is in good
shape given the most recent guidance.

...Mid-Atlantic...
A complex synoptic pattern will be present over the eastern U.S. as
a mid to upper level low slowly drifts from the Ohio Valley
towards the Mid-Atlantic, while a separate coastal low develops
offshore. Meanwhile, surface high pressure positioned to the north
will advect drier and more stable air into the corridor between
these two features.

Much of the deepest moisture and instability will remain offshore
with the coastal low. The primary threat for heavy rainfall over
land should focus closer to the cold core of the upper low from
the OH Valley down through western NC and into north GA. While PW
values will have lowered across this area, model guidance still
indicates CAPE exceeding 1000 J/kg within a trough axis over the
region.

This localized axis of instability, coupled with a stationary
convergence axis, will support the development of slow moving
convective cells. Even with the reduction in deep moisture, locally
heavy rainfall rates are likely. Given that at least some of this
region will have compromised FFG and heightened hydrologic
sensitivity from previous rainfall, some flash flood risk is
expected to continue.

Based on signals from the 00z REFS and HREF members, as well as
the GFS and ECMWF, a small Slight risk has been introduced
stretching from eastern TN into eastern KY and southern WV, where
the focus for slow moving convection is expected to be greatest.

...Florida...
A Marginal risk continues across south FL where above normal PWs
and instability will continue to pose a localized flash flood
risk.

Chenard/Taylor


Day 2 threat area: www.wpc.ncep.noaa.gov/qpf/98epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
835 PM EDT Tue Sep 22 2026
Day 3
Valid 12Z Thu Sep 24 2026 - 12Z Fri Sep 25 2026

..THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
NEW MEXICO AND THE TEXAS PANHANDLE...

...Southwest...
The stronger mid level forcing and highest PW anomalies will shift
northward out of NM and into Colorado and the central PLains on
Thursday. Despite the loss of stronger large scale forcing,
daytime destabilization over NM is actually forecast to increase
in the wake of the exiting system compared to prior days. While PW
values decrease some, they will remain above the climatological
75th percentile.

With less concentrated forcing and somewhat reduced moisture, the
overall areal coverage of heavy rainfall across NM should diminish
relative to days 1 and 2. However, the combination of stronger
instability and sufficient moisture will still support intense
localized convective rainfall rates capable of producing
significant rainfall totals. Given the hydrologic sensitivity
built up from preceding days of heavy rain, a Slight risk is
maintained for NM into the TX Panhandle. Locally significant flash
flood impacts will remain possible. Isolated to scattered flash
flooding will also be possible across portions of Arizona,
southeast Utah, and Colorado as shortwave energy lifts northward
across the region.

...Central Plains...
The deep moisture plume will maximize over the Central Plains on
Thursday, pushing PW values toward late September record levels.
The mid to upper pattern coupled with a robust low level moisture
transport axis supports a favorable setup for organized convection
across portions of KS and NE, with backbuilding/training a
possibility. There remains some uncertainty in the placement of the
heaviest rainfall and eventually a Slight Risk might be needed.

Chenard/Taylor

Day 3 threat area: www.wpc.ncep.noaa.gov/qpf/99epoints.txt

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
835 PM EDT Tue Sep 22 2026
Day 4 and Day 5

Valid 12Z Fri Sep 25 2026 - 12Z Sun Sep 27 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN US/WESTERN PLAINS AS WELL AS EASTERN NEW ENGLAND...

...Southern Rockies to Central and High Plains...

Day 4...Multiple areas of interest for the end of the week into the
weekend with a broad trough sweeping through the interior northwest
with a shortwave ejection out of the Rockies, enhancing regional
ascent within the Central High Plains into the Missouri River
Valley and adjacent Corn Belt. Model spread continues to be
relatively low with the handling of the two features leading to
better than normal confidence at range for a period of heavy rain
from widespread convection across the above area. Main axis of
heavy rainfall will likely be over central and eastern NE into
western IA and portions of northern KS and southern SD. Totals are
currently between 1-2" on areal average, but signal with
instability was sufficient for a broad MRGL risk placement
maintained over the area with only minor adjustments from the
previous forecast.

Further south over the Southern High Plains, a weak shortwave over
the Southern Rockies will advance east-northeast within the mean
mid-level flow with enough diurnal instability to couple with the
focused ascent pattern to cause a period of convective initiation
across the Southern High Plains of NM into the TX Panhandle.
Signals remains on the weaker side, but some of the areas
anticipated to be impacted will still be in recovery from the
barrage of heavy rain prospects the day prior, especially into NM.
A broad MRGL remains in effect for the above area.

Day 5...Main attention over the Midwest as the disturbance over the
northern tier of the CONUS migrates eastward and leads to a
carryover threat from the prior period. Models are less in
agreement on the overall threat, so the MRGL risk in place over the
Midwest into northern Missouri is of the lower end variety given
some of the model discrepancy. A period to monitor as there's an
equal chance of a higher risk and a removal pending the eventual
convective evolution.

...Eastern New England...

Day 4...Models remain consistent on the potential for a strong
synoptic surface low off northern Mid Atlantic coast with heavy
rain prospects in-of southeastern New England to perhaps as far
south as the northern Mid Atlantic coastal areas. As of the latest
ensemble probs and mean QPF distribution, the primary threat is
still over southern New England with southeastern MA into RI as
the areas of interest with 2+" totals plausible in the setup. The
one positive in this evolution is a limited convective footprint
leading to mainly heavy stratiform type precipitation coincident
with a Nor'Easter that tends to offer some flash flood threat, but
primarily leans more hydrological in terms of long term heavy rain
leading to swollen rivers and streams with urban flooding due to
poor drainage and consistent run off from prolonged rainfall. The
MRGL risk inherited was only adjusted a bit from the previous
issuance but maintaining the foothold over eastern MA into RI.

Day 5...There's some discrepancy in the southward push of heavy
rainfall (ML vs NWP outputs) as the upper pattern shows an
occluding low with a drift to the west or southwest over the course
of Saturday. Pending the upper level evolution, heavy rain
prospects could be felt as far south as the NJ coast, perhaps
leaking into portions of the Delmarva while still dealing more
rainfall into LI and portions of southern New England. At this
juncture, went with persistence in the forecast as higher probs
remains situated over southern New England, but will have to
monitor any trends backing more west to southwest with the
occluding low which would bring heavier rain and perhaps a shift of
the risk area further in that direction. Given the lack of
relevant instability with the setup, a MRGL risk is still the most
likely excessive outcome in the forecast, but positioning is where
there could be some changes in the coming days, pending trends in
guidance.

Kleebauer

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
835 PM EDT Tue Sep 22 2026
Day 4 and Day 5

Valid 12Z Fri Sep 25 2026 - 12Z Sun Sep 27 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN US/WESTERN PLAINS AS WELL AS EASTERN NEW ENGLAND...

...Southern Rockies to Central and High Plains...

Day 4...Multiple areas of interest for the end of the week into the
weekend with a broad trough sweeping through the interior northwest
with a shortwave ejection out of the Rockies, enhancing regional
ascent within the Central High Plains into the Missouri River
Valley and adjacent Corn Belt. Model spread continues to be
relatively low with the handling of the two features leading to
better than normal confidence at range for a period of heavy rain
from widespread convection across the above area. Main axis of
heavy rainfall will likely be over central and eastern NE into
western IA and portions of northern KS and southern SD. Totals are
currently between 1-2" on areal average, but signal with
instability was sufficient for a broad MRGL risk placement
maintained over the area with only minor adjustments from the
previous forecast.

Further south over the Southern High Plains, a weak shortwave over
the Southern Rockies will advance east-northeast within the mean
mid-level flow with enough diurnal instability to couple with the
focused ascent pattern to cause a period of convective initiation
across the Southern High Plains of NM into the TX Panhandle.
Signals remains on the weaker side, but some of the areas
anticipated to be impacted will still be in recovery from the
barrage of heavy rain prospects the day prior, especially into NM.
A broad MRGL remains in effect for the above area.

Day 5...Main attention over the Midwest as the disturbance over the
northern tier of the CONUS migrates eastward and leads to a
carryover threat from the prior period. Models are less in
agreement on the overall threat, so the MRGL risk in place over the
Midwest into northern Missouri is of the lower end variety given
some of the model discrepancy. A period to monitor as there's an
equal chance of a higher risk and a removal pending the eventual
convective evolution.

...Eastern New England...

Day 4...Models remain consistent on the potential for a strong
synoptic surface low off northern Mid Atlantic coast with heavy
rain prospects in-of southeastern New England to perhaps as far
south as the northern Mid Atlantic coastal areas. As of the latest
ensemble probs and mean QPF distribution, the primary threat is
still over southern New England with southeastern MA into RI as
the areas of interest with 2+" totals plausible in the setup. The
one positive in this evolution is a limited convective footprint
leading to mainly heavy stratiform type precipitation coincident
with a Nor'Easter that tends to offer some flash flood threat, but
primarily leans more hydrological in terms of long term heavy rain
leading to swollen rivers and streams with urban flooding due to
poor drainage and consistent run off from prolonged rainfall. The
MRGL risk inherited was only adjusted a bit from the previous
issuance but maintaining the foothold over eastern MA into RI.

Day 5...There's some discrepancy in the southward push of heavy
rainfall (ML vs NWP outputs) as the upper pattern shows an
occluding low with a drift to the west or southwest over the course
of Saturday. Pending the upper level evolution, heavy rain
prospects could be felt as far south as the NJ coast, perhaps
leaking into portions of the Delmarva while still dealing more
rainfall into LI and portions of southern New England. At this
juncture, went with persistence in the forecast as higher probs
remains situated over southern New England, but will have to
monitor any trends backing more west to southwest with the
occluding low which would bring heavier rain and perhaps a shift of
the risk area further in that direction. Given the lack of
relevant instability with the setup, a MRGL risk is still the most
likely excessive outcome in the forecast, but positioning is where
there could be some changes in the coming days, pending trends in
guidance.

Kleebauer

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
154 PM EDT Wed May 6 2026

Valid 00Z Thu May 07 2026 - 00Z Sun May 10 2026

...WPC Winter Weather Desk no longer routinely staffed until
late September, 2026...

Pending any significant winter weather, the WPC Winter Weather Desk
will not be staffed through the summer. The desk will resume
continuous staffing starting in the fall.

The WPC winter products will continue to be produced, however, and
all products except the heavy snow discussion (HSD) will be
available. This includes the Winter Storm Outlook (WSO), Winter
Storm Severity Index (WSSI), and Probabilistic Winter Precipitation
Forecasts (PWPF).


WPC

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
400 PM EDT Tue Sep 22 2026

Valid 12Z Fri Sep 25 2026 - 12Z Tue Sep 29 2026


...Impactful coastal storm meanders near the Mid-Atlantic and
Northeast
late week/weekend...


...Overview...

An upper low will stall atop the Mid-Atlantic and Northeast late
week into the weekend, supporting a meandering coastal surface low.
This pattern will lead to strong/gusty onshore winds for multiple
days, leading to coastal flooding, rip currents, high surf, and
potential beach erosion. Meanwhile, an upper ridge persisting in
the south-central U.S. will promote warm temperatures, while a
couple of upper troughs bring rounds of precipitation to parts of
the northwestern and north-central U.S. through the period.


...Guidance/Predictability Assessment...

Models continue to have a decent handle on the overall large scale
pattern through most of the medium range period, though some
uncertainty remains with smaller scale details. Case in point,
there is still a fair amount of spread with coastal low development
in the western Atlantic late week into the weekend underneath a
stalling upper low. The EC and especially the UKMET develop the low
farther south in the Atlantic Friday-Saturday, compared with most
other guidance sources which are farther north and east. The EC
continues to depict a track that reaches near Long Island or the
Jersey Shore by Sunday, while the farther northeast
GFS/AIGFS/CMC/ICON track the low just off the coast of New England.
The EC-AIFS, which was a reasonable middle ground in the previous
forecast, looks more like the EC for its 12Z run. By Monday-Tuesday
the low should be weaker but with remaining questions on when it
pulls away and from where. Given there is still ample spread
between two distinct camps, questions remain with respect to
sensible weather impacts like wind speed/direction and how much
rain falls onshore vs. offshore.

Elsewhere, guidance shows good consensus on the upper ridge in the
south-central U.S., though varying positions of weak fronts and
precipitation potential cause uncertainties in the temperatures.
The ridge looks to extend north and traverse the Midwest/Great
Lakes Friday and over the weekend, contributing to the blocky
pattern as it stretches into southeast Canada north of the Atlantic
upper low. Meanwhile a couple of trough axes will track across the
northwestern to north-central U.S. with typical spread in their
timing and depth. Guidance generally shows one crossing the Pacific
Northwest at the start of the period Friday, tracking across the
northern tier and lifting into central Canada on Sunday. Then an
upstream trough is forecast to move into the West Coast Sunday and
continue tracking east. By Monday into Tuesday models show varying
degrees of stream separation that affects the trough's timing.

Meanwhile, Hurricane Polo in the eastern Pacific has rapidly
intensified into a category 5 hurricane today, with continued
monitoring for downstream impacts later in the period. However,
despite Polo still having some model spread in its track, the
number of models/ensemble members depicting a curve into Baja
California are rapidly decreasing. A more suppressed track would
ultimately limit the amount of moisture that could be drawn
northward into the Southwest as a result.

The WPC forecast used a deterministic and AI model blend early in
the forecast period, then incorporated more ensemble means and
increased the weighting of said means to 50 percent by Days 6-7 to
mitigate the individual model differences in the details of the
pattern.


...Weather/Hazards Highlights...

The meandering surface low in the western Atlantic will lead to
broad onshore flow across the Mid-Atlantic and Northeast for
multiple days. This persistent pattern could lead to coastal
flooding and beach erosion concerns, especially when combined with
high astronomical tides. Exact placement of the surface low from
day to day and thus any heavy rain is more uncertain. The latest
forecast continues to offer support that coastal New England may
see heavy rainfall on Friday into the weekend. However, stay tuned
for forecast updates, as small shifts in the low track would lead
to significant forecast shifts in rainfall amounts. See WPC's Key
Messages for this coastal low for further information.

Pacific moisture is forecast to advect around the western side of
the south-central U.S. upper ridge and lead to some rain across
parts of the central U.S. on Friday. If/where additional rain falls
in New Mexico, there could be flooding concerns after the forecast
heavy rainfall event in the short range causes very wet antecedent
conditions. Meanwhile farther east and northeast into the Plains,
moderate to locally heavy rainfall may be possible, but on less
sensitive ground. Rain chances persist in the Upper/Middle
Mississippi Valley into Saturday. Meanwhile, upper troughing will
bring precipitation to the Pacific Northwest and northern Rockies,
including higher elevation snow chances, on Friday. Scattered
showers and thunderstorms are again possible in parts of the
Plains/Mississippi Valley on Sunday, but a more widespread rainy
pattern with potentially heavier amounts is possible Monday into
Tuesday as Pacific and Gulf moisture combine and stream into the
central U.S. ahead of troughing in the West.

Temperatures are forecast to remain cooler than average by 5-10
degrees in the Mid-Atlantic and Northeast into the weekend
underneath the upper low, and highs will generally be in the 60s.
On the other hand, broad upper ridging over the south-central U.S.
could maintain highs in the 90s for the southern Plains and Lower
Mississippi Valley. Cooler than normal temperatures are likely in
the Northwest given troughing aloft, which should push into the
northern Rockies/High Plains after a warmer than average period
into Friday.


Tate/Miller


Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php

WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation forecast, excessive rainfall outlook,
winter weather outlook probabilities, heat indices and Key Messages
are at:

https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/#page=ero
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml
https://www.wpc.ncep.noaa.gov/#page=ovw