Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
309 AM EDT Mon Oct 19 2026

Valid 12Z Mon Oct 19 2026 - 12Z Wed Oct 21 2026

...Flash Flooding risk for portions of the Southwest on Monday...

...Norâ€easter moving north just off the Mid-Atlantic Coast will produce
rain showers along parts of the Mid-Atlantic and Northeast Coast through
Tuesday...

...Low pressure moving southward along the West Coast will bring scattered
showers across parts of California through Tuesday...


A non-tropical low pressure offshore of the Carolinas will continue to
strengthen while slowly moving northward along the western Atlantic. The
system is expected to maintain a broad circulation offshore, with moisture
wrapping around the low, supporting possible showers and thunderstorms
along portions of the Mid-Atlantic and Northeast coastline through
Wednesday. Persistent onshore flow will be favored by the pressure
gradient between the coastal low and the high pressure farther inland.
Therefore, the strong northeasterly winds will continue to affect coastal
portions of the Mid-Atlantic, particularly from the southern New Jersey
through the Virginia Tidewater and North Carolina Outer Banks. The prolong
onshore flow will bring moderate coastal flooding, dangerous marine
conditions, and beach erosion.

Farther west, an upper-level disturbance and associated areas of low
pressure over eastern Pacific will progress southward along the West
Coast. Increasing ascent ahead of the disturbance, combined with Pacific
moisture and cooling aloft, will support scattered rainfall across
portions of the northern California coast on Monday. Showers and
thunderstorms is expected to spread into central and southern California
by Tuesday. Some showers and thunderstorms may also develop over portions
of the Great Basin and Southwest as the upper-level disturbance moves
inland through early Wednesday. The greatest potential for locally heavy
rainfall and isolated flash flooding will be on Monday across southeastern
Arizona and southwestern New Mexico, where remnant upper-level energy,
enhanced Pacific moisture, and instability will support scattered
thunderstorms. Across the Southeast, a weak frontal boundary and
persistent easterly flow off the Atlantic will maintain scattered showers
and thunderstorms across portions of the Florida peninsula through
Tuesday.


Oudit


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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
405 AM EDT Mon Oct 19 2026

Valid 12Z Thu Oct 22 2026 - 12Z Mon Oct 26 2026


...Lingering Nor'easter offers East Coast Maritime Impacts...

...Southern California/Southwest/Rockies Heavy Precipitation...


...Overview...

A lingering Nor'easter will bring wind and coastal flooding
impacts to the East Coast into mid-late week. A cutoff low will
support heavy rainfall from Southern California to the Four
Corners states mid-to-late week along with some mountain snows.
Associated activity will spread through the West Rockies and then
work downstream with PLains system genesis. There is also an
emerging onshore wet pattern for Florida to monitor late period.


...Guidance/Predictability Assessment...

Models are in good agreement on the overall synoptic evolution of
the mid-level pattern beginning mid-week. The amplitude of a
Western Atlantic trough is the most uncertain aspect of the late
week portion of the medium range. Beyond that, the timing/speed of
another West Coast trough carries the most model dispersion this
weekend.

The AiGFS is favored in the days 3-7 blend with other pieces of
guidance used less consistently. The ensemble means make up 60% of
the blend by day 5, due to growing variance with respect to an
incoming shortwave out of British Columbia. The ensemble mean
maintain favorable weighting through the end of the period.


...Weather/Hazards Highlights...

A Nor'easter will offer threats for high winds and coastal
flooding with stormy maritime conditions from the coastal Mid-
Atlantic to off the Northeast. The storm will intensify off the
Carolinas over the next few days and bring strong winds back
to the coastline into mid-late week to protract a threat for beach
erosion. The storm offers potential subtropical transition to
monitor later week per NHC. Please refer to WPC's Key Messages on
our website for more information: www.wpc.ncep.noaa.gov.

A shortwave passing south of the Gulf of Alaska is forecast to
dig/amplify into a cut-off low over the Eastern Pacific just off
the West Coast into midweek and work inland into California and
the Southwest later week. Anomalous moisture will feed into the
West to support increasingly widespread rain/thunderstorms over the
region and through the Great Basin/Rockies. There's a slight risk
(at least 15% chance) of excessive rainfall leading to flash
flooding for portions of the Four Corners region, with a strong
signal for heavy rainfall over the San Juan Mountains as well as
the general southwestern Colorado area peaking on Thursday. The
slow moving system will then eject downstream and lead cycle/fronts
genesis and return flow should support emerging
showers/thunderstorms over the Plains by next weekend, albeit still
with timing uncertainty to navigate.

Upstream, a closed low with ample upper troughing will dig from
the Gulf of Alaska to approach the Northwest and/or offshore late
week. This system could generate moderate precipitation including
high elevation snows into the Northwest as dependent on ultimate
inland penetration to monitor with upcoming guidance.

Meanwhile, mean upper trough development and lingering down though
the Southeast U.S. may lead into a wet onshore flow period for
especially southern Florida late period into next week. An upper
ridge will amplify over the Central U.S. leading to above average
temperatures across the region through this weekend.

Kebede/Schichtel


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
340 AM EDT Mon Oct 19 2026

Valid 00Z Tue 20 Oct 2026 - 00Z Tue 27 Oct 2026

Hawaii and the adjacent waters will be to the south of a
subtropical high that will be situated near 35 degrees north for
the beginning of this week, with steady ENE trade winds expected
through Wednesday. A well defined col develops within this
subtropical high by Wednesday night as a developing low pressure
system over the North Pacific heads towards the ESE and brings a
frontal boundary closer to the northwestern Islands, and therefore
weaker and more variable winds.

The guidance also starts to diverge on how this system evolves
north of the state towards the end of the week. The GEFS mean
becomes more progressive and stronger, and has the low well to
the northeast of the ECENS mean. Going into the weekend, the ECENS
favors more of an inverted surface trough, whereas the GEFS
maintains a closed low northeast of the Islands. The deepest
tropical moisture should stay confined well to the south, but some
higher PWs and increased rainfall chances arrive by Friday and
into Saturday as the trough advects some of this moisture towards
the north.

Hamrick

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Mon Oct 19 2026
Day 1
Valid 12Z Mon Oct 19 2026 - 12Z Tue Oct 20 2026

..THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHWEST...

A positively tilted upper level trough shears eastward ahead of a
deep layer cyclone dropping offshore the West Coast today helping
to trigger widely scattered thunderstorms. An influx of anomalous
moisture by mid October standards (precipitable water values of
0.75-1") from the Pacific and sufficient instability (1000-1500
J/KG MLCAPE) should support locally heavy downpours. Integrated
Vapor Transport eclipses 250 kg/ms. The ingredients available
suggest that 2" an hour amounts are possible where sufficient cell
coverage exists, which appears to be the main issue/reason why the
risk level is Marginal. The heaviest rains would be due to cell
mergers, random training, or where cells are
stationary/backbuilding. This degree of rainfall would be
problematic in urban areas, burn scars, box/slot canyons, and dry
washes/arroyos.

Roth


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Mon Oct 19 2026
Day 2
Valid 12Z Tue Oct 20 2026 - 12Z Wed Oct 21 2026

...Southwest...
Anomalous moisture will remain in place Tuesday ahead of the deep
layer cyclone digging southward offshore CA. Integrated Vapor
Transport broaches 500 kg/ms by early Wednesday morning, with the
main increase after daytime heating. However, overall instability
remains fairly low with splotches of 500 J/kg of MU CAPE available.
The risk for heavy rainfall and flash flooding is non-zero, but
appears to be below the 5 percent threshold at the present time.

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Roth


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Mon Oct 19 2026
Day 3
Valid 12Z Wed Oct 21 2026 - 12Z Thu Oct 22 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHWEST WEDNESDAY/WEDNESDAY NIGHT...

...Southwest...
On Wednesday/Wednesday night, a deep layer cyclone moves into
southwest CA and scoops up moisture from a dying Trudy, flinging
it into the Southwest. A broadening zone of 300-600 kg/ms of
Integrated Vapor Transport envelops the Southwest. Near the cold
low itself, MU CAPE of 500+ J/kg and precipitable water values of
1-1.3" with up to 30 kts of onshore flow at 850 hPa is forecast,
which would support hourly amounts to 2" where cells manage to
train or backbuild within the terrain. There are enough
ingredients available/heavy rain signal for the existing Marginal
Risk for the Transverse and Peninsular Ranges, which is there to
help cover burn scar concerns.

Across portions of the Southwest, MU/ML CAPE is forecast to rise
to 1000-1500 J/kg with lesser amounts to the north across the Great
Basin/Rockies, with precipitable water values rising into 0.75-1.5"
range. The ingredients available along with deterministic guidance
QPF output appear sufficient to maintain the existing Slight Risk.
Hourly rain amounts to 2.5" would be possible across portions of
AZ, NM, and the Four Corners in widely scattered to scattered
spots. Urban areas, burn scars, slot/box canyons, and dry
washes/arroyos would be the main areas of concern with the heavy
rainfall anticipated.

Roth

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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Mon Oct 19 2026
Day 4 and Day 5

Valid 12Z Thu Oct 22 2026 - 12Z Sat Oct 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHWEST THURSDAY...

Maintained the Slight Risk area in parts of the Southwest on
Thursday as a deep mid/upper level low moves across the region.
Heavy to potentially excessive rainfall remains a concern given the
magnitude of the tropical moisture being advected into the region. Deep
southerly flow ahead of the approaching trough will advect
an airmass with precipitable water values that approach record
values for the latter part of October. There is still spread in the
amount of instability available by then but the overall uptick in
model QPF over the past couple of runs is indicative of the models
are doing better at capturing the steepening lapse rates with the
upper low on Thursday should also produce some destabilization.

By Friday, the trough axis has have made its way across the
southern Rockies and emerged out over the adjacent High Plains.
Some of the moisture will be lost in the complex terrain as the
system moves eastward...but additional low level moisture should
start being drawn out of the Gulf to support a lower-end risk of
excessive rainfall lingering over portions of New Mexico and
portions of adjoining states.

Even though confidence on the exact details remain low given we
are 4 to 5 days out, there is growing confidence in a heavy rain
and flash flood threat over the Southwest region beginning on Day 3
which continues into Thursday. The ingredients in place still
suggest that at least locally significant impacts are a
possibility. Trends will continue to be monitored and can not rule
out the need for embedded MDT risk area(s) if/where enough
instability materializes.

Bann

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Mon Oct 19 2026
Day 4 and Day 5

Valid 12Z Thu Oct 22 2026 - 12Z Sat Oct 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHWEST THURSDAY...

Maintained the Slight Risk area in parts of the Southwest on
Thursday as a deep mid/upper level low moves across the region.
Heavy to potentially excessive rainfall remains a concern given the
magnitude of the tropical moisture being advected into the region. Deep
southerly flow ahead of the approaching trough will advect
an airmass with precipitable water values that approach record
values for the latter part of October. There is still spread in the
amount of instability available by then but the overall uptick in
model QPF over the past couple of runs is indicative of the models
are doing better at capturing the steepening lapse rates with the
upper low on Thursday should also produce some destabilization.

By Friday, the trough axis has have made its way across the
southern Rockies and emerged out over the adjacent High Plains.
Some of the moisture will be lost in the complex terrain as the
system moves eastward...but additional low level moisture should
start being drawn out of the Gulf to support a lower-end risk of
excessive rainfall lingering over portions of New Mexico and
portions of adjoining states.

Even though confidence on the exact details remain low given we
are 4 to 5 days out, there is growing confidence in a heavy rain
and flash flood threat over the Southwest region beginning on Day 3
which continues into Thursday. The ingredients in place still
suggest that at least locally significant impacts are a
possibility. Trends will continue to be monitored and can not rule
out the need for embedded MDT risk area(s) if/where enough
instability materializes.

Bann

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
222 AM EDT Mon Oct 19 2026

Valid 12Z Mon Oct 19 2026 - 12Z Thu Oct 22 2026

...Southern Sierra Nevada...

Day 3...

A highly anomalous upper-low off the Southern CA coast
(standardized anomalies as much as -4 sigma at 500mb and 700mb by
12Z
Wed) will work in tandem with an upper-level ridge over the
Nation's Heartland to tap into rich tropical East Pacific moisture
and direct this moisture at the Southwest U.S.. 850-500mb mean flow
out of the south will provide a favorable setup for upslope-
enhanced precipitation rates long the southern Sierra Nevada. That
said, the antecedent air-mass is not overly cold and the colder
temperatures within the closed low are well offshore. This will
keep snowfall confined to the higher elevations of the southern
Sierra Nevada on Wednesday (above 9,000ft). The Probabilistic
Precipitation Portal (PPP) shows low chances (10-30%) for snowfall
totals >4" above 10,000ft. The Probabilistic Winter Storm Severity
Index (WSSI-P) also show low chances (10-30%) as low as 9,000ft in
elevations. This could result in some slick conditions in the
rugged terrain of the southern Sierra Nevada mid-week.


Mullinax

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
405 AM EDT Mon Oct 19 2026

Valid 12Z Thu Oct 22 2026 - 12Z Mon Oct 26 2026


...Lingering Nor'easter offers East Coast Maritime Impacts...

...Southern California/Southwest/Rockies Heavy Precipitation...


...Overview...

A lingering Nor'easter will bring wind and coastal flooding
impacts to the East Coast into mid-late week. A cutoff low will
support heavy rainfall from Southern California to the Four
Corners states mid-to-late week along with some mountain snows.
Associated activity will spread through the West Rockies and then
work downstream with PLains system genesis. There is also an
emerging onshore wet pattern for Florida to monitor late period.


...Guidance/Predictability Assessment...

Models are in good agreement on the overall synoptic evolution of
the mid-level pattern beginning mid-week. The amplitude of a
Western Atlantic trough is the most uncertain aspect of the late
week portion of the medium range. Beyond that, the timing/speed of
another West Coast trough carries the most model dispersion this
weekend.

The AiGFS is favored in the days 3-7 blend with other pieces of
guidance used less consistently. The ensemble means make up 60% of
the blend by day 5, due to growing variance with respect to an
incoming shortwave out of British Columbia. The ensemble mean
maintain favorable weighting through the end of the period.


...Weather/Hazards Highlights...

A Nor'easter will offer threats for high winds and coastal
flooding with stormy maritime conditions from the coastal Mid-
Atlantic to off the Northeast. The storm will intensify off the
Carolinas over the next few days and bring strong winds back
to the coastline into mid-late week to protract a threat for beach
erosion. The storm offers potential subtropical transition to
monitor later week per NHC. Please refer to WPC's Key Messages on
our website for more information: www.wpc.ncep.noaa.gov.

A shortwave passing south of the Gulf of Alaska is forecast to
dig/amplify into a cut-off low over the Eastern Pacific just off
the West Coast into midweek and work inland into California and
the Southwest later week. Anomalous moisture will feed into the
West to support increasingly widespread rain/thunderstorms over the
region and through the Great Basin/Rockies. There's a slight risk
(at least 15% chance) of excessive rainfall leading to flash
flooding for portions of the Four Corners region, with a strong
signal for heavy rainfall over the San Juan Mountains as well as
the general southwestern Colorado area peaking on Thursday. The
slow moving system will then eject downstream and lead cycle/fronts
genesis and return flow should support emerging
showers/thunderstorms over the Plains by next weekend, albeit still
with timing uncertainty to navigate.

Upstream, a closed low with ample upper troughing will dig from
the Gulf of Alaska to approach the Northwest and/or offshore late
week. This system could generate moderate precipitation including
high elevation snows into the Northwest as dependent on ultimate
inland penetration to monitor with upcoming guidance.

Meanwhile, mean upper trough development and lingering down though
the Southeast U.S. may lead into a wet onshore flow period for
especially southern Florida late period into next week. An upper
ridge will amplify over the Central U.S. leading to above average
temperatures across the region through this weekend.

Kebede/Schichtel


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