Weather Prediction Center

National Oceanic and Atmospheric Administration

Short Range Forecast Discussion
NWS Weather Prediction Center College Park MD
151 AM EST Thu Dec 25 2025

Valid 12Z Thu Dec 25 2025 - 12Z Sat Dec 27 2025

...There is a Moderate Risk of excessive rainfall over parts of Southern
California on Thursday...

...Heavy snow over parts of the Sierra Nevada Mountains, Cascades,
Northern Intermountain Region, Northern/Central Rockies, and Northeast...

...Up to 0.25 inches of rain/freezing rain possible over the
Pennsylvania...

Low pressure over the Ohio Valley will move eastward off the Northeast
Coast by Thursday evening. The system will usher in rain over parts of the
Ohio Valley to the Mid-Atlantic by Christmas. Additionally, snow will
develop over parts of the Northeast on Thursday. A second low over the
Upper Mid-West Thursday evening will move off the Eastern Seaboard by
Saturday. With the second low, an icy wintry mix of freezing rain and
sleet will cause hazardous travel conditions from Michigan eastward across
much of Pennsylvania and into the Mid-Atlantic. Up to 0.25 inches of
rain/freezing rain is possible over parts of Pennsylvania. Snow will also
develop over the U P of Michigan. In addition, moderate to heavy snow will
develop over New England Friday into Saturday morning.

Meanwhile, a broad plume of moisture will move over California, with rain
moving into California and the Great Basin. A stream of moisture-laden air
will produce heavy rain over California on Thursday, with heavy rain
developing over parts of Southern California. Therefore, the WPC has
issued a Moderate Risk (level 3/4) of excessive rainfall over parts of
Southern California from Thursday into Friday morning. Numerous flash
flooding events are possible. In addition, many streams may flood,
potentially affecting larger rivers. The flooding may include debris flows
in or near recently burned areas. Additionally, a Slight Risk of excessive
rainfall will develop over Northern/Central California and into parts of
Southern Nevada on Thursday.

On Friday, the heavy rain will continue over California. Therefore, the
WPC has issued a Slight Risk (level 2/4) of excessive rainfall from Friday
into Saturday morning. The associated heavy rain will create mainly
localized areas of flash flooding, with urban areas, roads, small streams,
and burn scars being the most vulnerable. Moreover, heavy snow will
develop over the Sierra Nevada Mountains through Saturday. While rain and
snow at the highest elevations will develop over the Great Basin and the
Southwest through Saturday.

Ziegenfelder



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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 AM EST Thu Dec 25 2025

Valid 12Z Sun Dec 28 2025 - 12Z Thu Jan 01 2026


...Overview...

Leading and initially amplified upper ridging will shift through
the east-central U.S. into the weekend, as split upper troughing
shifts inland over the West to bring an end to a very wet period,
especially impacting California. Unseasonably warm temperatures
will continue for the central and eastern states into the weekend
prior to a stark front pushes through. The northern tier will be
in an active pattern with multiple rounds of plowable snow for the
Great Lakes and into the Mid-Atlantic and Northeast regions. Lake
enhanced snow possible in the wake of the main low passage by
Sunday/Monday.

...Guidance/Predictability Assessment...

The latest suite of guidance continues to have a good handle on the
large scale pattern, especially early on. A general model blend was
utilized for the first few periods. As previously noted, there is
potential for phasing of a positively tilted trough extending from
the Central U.S. into the Desert Southwest which will timing and
location of sensible weather especially for the eastern half of
the nation. The WPC blend was comprised of the GFS/ECMWF/UKMET/CMC
initially and then included the EC/CMC/GFS ensembles.

...Weather/Hazards Highlights...

Leading shallow shortwaves moving through the northern tier and
associated surface system reflection and possible flow
amplification with the digging of northern stream upper troughing
into the lower 48 will bring some precipitation chances to the
Great Lakes through the north-central Appalachians and northern
Mid-Atlantic/Northeast to include chances for enhanced snow/ice.

Temperatures will continue to be anomalously warm from the central
to east-central U.S. mid-lower latitudes into Saturday. Daytime
highs 25-30+ degrees above normal may set daytime and warm morning
low records. The airmass moves east with time and moderates. A
significant drop in temperatures expected for the central and
eastern U.S. as the northern stream trough amplifies. In contrast,
temperatures out West will moderate by early next week with upper
ridging.

The guidance is hinting that heavier precipitation chances into
the Pacific Northwest/Northwest with renewed/windy onshore flow, as
well as potential renewed precipitation over parts of SoCal in
about a week lending into the Climate Prediction Center's week 2
forecast to ring in 2026.

Campbell/Kebede


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 (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

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
351 AM EST Thu Dec 25 2025

Valid 00Z Fri 26 Dec 2025 - 00Z Fri 02 Jan 2026

An upper-level ridge centered over the islands will maintain
stable conditions at the start of the period, while a robust
surface high to the north continues to drive the synoptic pattern.
Simultaneously, the surface high will migrate east, allowing the
pressure gradient to relax and surface winds to veer to a more
southeasterly direction. This will introduce a relatively drier
airmass from the east that will remain in place into the weekend.

The pattern is expected to transition late in the weekend as the
upper ridge shifts eastward, and by Monday, an upper-level trough
is forecast to move across the central Pacific north of the state.
This feature will push a cold front toward the western islands.
While model guidance remains uncertain regarding the precise
timing of this boundary, the general consensus favors the front
stalling and weakening in the vicinity of the western islands
during the first half of the week. Ahead of this feature, the
global guidance shows an uptick in PWATS, likely approaching or
exceeding 1.5+ inches, as ML CAPEs likely reach 250-500+ J/Kg.
This will bring an increased risk for showers during the early
part of next week, particularly over more elevated windward
slopes, followed by a return to more standard northeasterly trades
as high pressure and a drier regime build back across the Islands
to start off the new year.

Hurley

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
201 AM EST Thu Dec 25 2025
Day 1
Valid 12Z Thu Dec 25 2025 - 12Z Fri Dec 26 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN CALIFORNIA...

A Moderate Risk remains in effect for a large portion of the
Central CA coast through much of the Transverse Ranges north of
L.A. While the main AR has pushed south and weakened, the
amplifying upper trough offshore and strengthening lee-side jet
streak will reinvigorate deep-layer forcing downstream across
Southern CA. Meanwhile, the colder air aloft will help provide some
deep-layer instability (MUCAPES 250-500 J/Kg), thus supportive of
additional rounds of 0.50-1.00 inch/hr rainfall rates as a
secondary axis of elevated PWATs (0.80-1.10") and IVTs (500-600
Kg/m/s) traverses the Moderate Risk area. Additional rainfall
amounts of 2 to 4+ inches are expected within the Moderate Risk
area, with the guidance (especially high-res CAMs) indicating
isolated additional totals between 5 and 7+ inches across the
southern slopes of the Transverse Ranges. As such, we continued to
outlook a "high-end" Moderate Risk -- denoting a more enhanced or
>50% neighborhood probability of rainfall exceeding flash flood
guidance -- across the San Rafael and southern Sierra Madre Ranges,
where the 00Z HREF indicated 80%+ probabilities of additional
rainfall exceeding 3" through 12Z Fri, along with 30-50%
probabilities of rainfall totals exceeding 5".

Elsewhere, the Slight Risk area was expanded across parts of the
Central Valley based on Wednesday's rainfall along with the
deterministic and probabilistic QPF Christmas Day through 12Z Fri.
No changes were made to the broader Marginal Risk area based on the
latest (00Z) guidance/trends.

Hurley


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
201 AM EST Thu Dec 25 2025
Day 2
Valid 12Z Fri Dec 26 2025 - 12Z Sat Dec 27 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS SOUTHERN
CALIFORNIA...

Minor changes were made to the Slight and Marginal Risk areas from
yesterday's Day 3 ERO. The secondary (weaker) Atmospheric River
will be waning, however given the significant accumulations
leading up to this period, soils will remain hyper sensitive to
any additional precipitation, particularly across the Transverse
Range and surrounding locations. As such, a Slight Risk area was
maintained for this part of the state along with a Marginal Risk
that extends up the coast toward San Francisco and along the
foothills of the Sierra Nevada Range.

Hurley


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

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
201 AM EST Thu Dec 25 2025
Day 3
Valid 12Z Sat Dec 27 2025 - 12Z Sun Dec 28 2025

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

Hurley

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

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 AM EST Thu Dec 25 2025


Leading shallow shortwaves moving through the northern tier and
associated surface system reflection and possible flow
amplification with the digging of northern stream upper troughing
into the lower 48 will bring some precipitation chances to the
Great Lakes through the north-central Appalachians and northern
Mid-Atlantic/Northeast to include chances for enhanced snow/ice.

Temperatures will continue to be anomalously warm from the central
to east-central U.S. mid-lower latitudes into Saturday. Daytime
highs 25-30+ degrees above normal may set daytime and warm morning
low records. The airmass moves east with time and moderates. A
significant drop in temperatures expected for the central and
eastern U.S. as the northern stream trough amplifies. In contrast,
temperatures out West will moderate by early next week with upper
ridging.

The guidance is hinting that heavier precipitation chances into
the Pacific Northwest/Northwest with renewed/windy onshore flow, as
well as potential renewed precipitation over parts of SoCal in
about a week lending into the Climate Prediction Center's week 2
forecast to ring in 2026.

Campbell/Kebede

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 AM EST Thu Dec 25 2025


Leading shallow shortwaves moving through the northern tier and
associated surface system reflection and possible flow
amplification with the digging of northern stream upper troughing
into the lower 48 will bring some precipitation chances to the
Great Lakes through the north-central Appalachians and northern
Mid-Atlantic/Northeast to include chances for enhanced snow/ice.

Temperatures will continue to be anomalously warm from the central
to east-central U.S. mid-lower latitudes into Saturday. Daytime
highs 25-30+ degrees above normal may set daytime and warm morning
low records. The airmass moves east with time and moderates. A
significant drop in temperatures expected for the central and
eastern U.S. as the northern stream trough amplifies. In contrast,
temperatures out West will moderate by early next week with upper
ridging.

The guidance is hinting that heavier precipitation chances into
the Pacific Northwest/Northwest with renewed/windy onshore flow, as
well as potential renewed precipitation over parts of SoCal in
about a week lending into the Climate Prediction Center's week 2
forecast to ring in 2026.

Campbell/Kebede

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
203 AM EST Thu Dec 25 2025

Valid 12Z Thu Dec 25 2025 - 12Z Sun Dec 28 2025

*** Continued Heavy Snow on the Sierra Nevada through Friday ***


...Great Lakes to Northeast...
Days 1-2... Maximum impact level from WSSI: Moderate

Quasi-zonal flow will direct a plume of moisture originating from
the West along the US/Canadian border today/tonight with WAA-driven
snow over the MN Arrowhead into the U.P. of Michigan. With cold
sub-32F sfc temps over parts of MN/WI/Lower MI at precip onset
tonight, some freezing rain is likely with minor accumulations over
MN/WI. WPC probabilities for at least 4 inches of snow are low to
moderate (20-60%) over the far northeastern MN Arrowhead into the
Keweenaw Peninsula.

Into D2, shortwave will push through northern Lower MI with its
sfc reflection over IN/OH and the 850mb low moving through BUF. The
sfc low will weaken as it approaches the Appalachians, getting too
far behind the mid-level shortwave, and ultimately jumping into
the Atlantic by 12Z Sat. From Friday to Saturday morning, a variety
of ptypes are expected over the region (central Appalachians/Mid-
Atlantic to the Northeast). The stubborn cold surface air will hold
tight over Lower MI and especially into the Laurel Highlands in
western PA where significant freezing rain is possible. WPC
probabilities of at least 0.10" icing are high (>70%) from around
Detroit and into western PA/western MD, with 40-60% probabilities
of at least 0.25" icing in these areas as well. Light icing is
likely on either side of this zone of maximum probabilities -- on
the south side along the I-66 corridor (DC) and into eastern WV. To
the north/northeast, deeper cold air at the surface will allow for
sleet to be a dominant ptype over central/eastern PA with up to an
inch of so possible. To the north, from central NYS through
northeast PA into the Catskills/Poconos and to the NYC Metro area,
an axis of moderate snow is possible, driven by the stronger height
falls at the nose of the incoming 130kt jet. The whole scenario is
still uncertain in where the transition zones align as some of the
00Z guidance (e.g., the NAM) were much farther northeast with the
WAA than the other global guidance. The recent trend has been
toward this milder scenario but only nudged the forecast somewhat
given the lead time still.

WPC probabilities for at least 4 inches of snow are >50% in a zone
bounded between I-890/Rt 17/I-476 to the west, the southern
Adirondacks on the north side, Berkshires/I-91 to the east, and
into the NYC Metro/Long Island to the south. Though the system will
be progressive, combination of higher SLRs and upslope could yield
more than 8 inches of snow into the southern Catskills.


...California/Sierra Nevada...
Days 1-3... Maximum impact level from WSSI: Extreme

The next moisture plume with the long-lived atmospheric river
event will arrive this morning into CA amid lower snow levels
around 55000-6500ft and heavy snow rates of 2-4"/hr through midday
before rates again decrease in showery conditions through the
afternoon. The last larger punch of moisture arrives this
evening/overnight with persistent snow levels of 5500/6500ft
through the night before dropping to 5000ft for Friday with
continued moderately heavy rates (1-2"/hr). Precipitation is
expected to finally wane by Friday night as the upper trough moves
ashore with ridging to follow. The lower snow levels and rounds of
heavy snow through Friday will lead to increasing travel and
infrastructure impacts. Additional snowfall of 2-5ft can be
expected above 6000ft along the extent of the Sierra Nevada.

Far northern CA ranges (Shasta Siskiyou/Klamath/etc) can expect
moderately heavy snow above 4000ft or so as snow levels dip to
start the period. Some snow impacts to I-5 near Mt Shasta are
possible mainly early Friday. Most snow will end by 12Z Saturday.
Over SoCal, snow levels drop to around 7000ft tonight where they
linger through Friday. Impactful snow looks to remain higher than
Big Bear Lake.

Key Messages for the CA atmospheric river and subsequent low that
maintains impacts through Friday are linked below.


...Pacific Northwest, Great Basin and Rockies...
Days 1-3... Maximum impact level from WSSI: Moderate to Major

Though the AR affecting CA will infuse some moisture into the
Rockies, an incoming trough out of the Gulf of Alaska will drop
into the PacNW on Friday with a renewed increase of moisture to the
area as snow levels remain on the lower side -- generally
2500-3500ft in the Cascades. That trough will exit WA early
Saturday and bring widespread light to moderate snows to the
northern Rockies the CA AR (via the separate upper trough) moves
inland as well. This will act to expand the area of snow across
most of the Great Basin to central Rockies Saturday into early
Sunday before the entire full- latitude trough then exits onto the
Plains just beyond this forecast period. Snow levels will be much
lower over MT/ID and western WY compared to UT/CO (closer to the
warmer AR) -- generally 4000ft to the north (and falling to the
valley floors) ramping up to around 7000-8000ft over CO, falling to
below 6000ft by early Sunday morning.

For days 1-2, WPC probabilities for at least 12 inches are >50%
above about 2500ft in the WA Cascades (still affecting the passes),
5000ft in western MT, 6000ft in central ID, 7000-8000ft in the
western WY ranges, and about 9000ft in the Uintas. For days 2-3,
the focus will be on the CO Rockies where WPC probabilities for at
least 8 inches of snow are >50% above about 9000ft.


Fracasso


...Winter Storm Key Messages are in effect. Please see current
Key Messages below...

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_2.png

Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
233 AM EST Thu Dec 25 2025

Valid 12Z Sun Dec 28 2025 - 12Z Thu Jan 01 2026


...Overview...

Leading and initially amplified upper ridging will shift through
the east-central U.S. into the weekend, as split upper troughing
shifts inland over the West to bring an end to a very wet period,
especially impacting California. Unseasonably warm temperatures
will continue for the central and eastern states into the weekend
prior to a stark front pushes through. The northern tier will be
in an active pattern with multiple rounds of plowable snow for the
Great Lakes and into the Mid-Atlantic and Northeast regions. Lake
enhanced snow possible in the wake of the main low passage by
Sunday/Monday.

...Guidance/Predictability Assessment...

The latest suite of guidance continues to have a good handle on the
large scale pattern, especially early on. A general model blend was
utilized for the first few periods. As previously noted, there is
potential for phasing of a positively tilted trough extending from
the Central U.S. into the Desert Southwest which will timing and
location of sensible weather especially for the eastern half of
the nation. The WPC blend was comprised of the GFS/ECMWF/UKMET/CMC
initially and then included the EC/CMC/GFS ensembles.

...Weather/Hazards Highlights...

Leading shallow shortwaves moving through the northern tier and
associated surface system reflection and possible flow
amplification with the digging of northern stream upper troughing
into the lower 48 will bring some precipitation chances to the
Great Lakes through the north-central Appalachians and northern
Mid-Atlantic/Northeast to include chances for enhanced snow/ice.

Temperatures will continue to be anomalously warm from the central
to east-central U.S. mid-lower latitudes into Saturday. Daytime
highs 25-30+ degrees above normal may set daytime and warm morning
low records. The airmass moves east with time and moderates. A
significant drop in temperatures expected for the central and
eastern U.S. as the northern stream trough amplifies. In contrast,
temperatures out West will moderate by early next week with upper
ridging.

The guidance is hinting that heavier precipitation chances into
the Pacific Northwest/Northwest with renewed/windy onshore flow, as
well as potential renewed precipitation over parts of SoCal in
about a week lending into the Climate Prediction Center's week 2
forecast to ring in 2026.

Campbell/Kebede


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 (QPF), excessive rainfall
outlook (ERO), winter weather outlook (WWO) probabilities, heat
indices, and Key Messages can be accessed from:

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