635
FXUS21 KWNC 222046
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST DECEMBER 22 2025
SYNOPSIS: MID-LEVEL LOW PRESSURE OVER THE NORTHEASTERN PACIFIC IS EXPECTED TO
EXPAND SOUTHWARD THROUGHOUT WEEK-2, BRINGING INCREASED RISK OF HEAVY
PRECIPITATION AND HEAVY SNOW INITIALLY TO THE PACIFIC NORTHWEST, EXPANDING
SOUTHWARD TO PARTS OF CALIFORNIA BY THE MIDDLE OF THE PERIOD. THE ENHANCED
PACIFIC FLOW FAVORS HEAVY SNOW ACROSS THE NORTHERN ROCKIES AND AN ELEVATED
CHANCE OF HIGH WINDS OVER MUCH OF THE WESTERN AND CENTRAL U.S. STRONG MID-LEVEL
HIGH PRESSURE OVER THE BERING SEA IS LIKELY TO PROMOTE PERSISTENT ARCTIC HIGH
PRESSURE AND ANOMALOUSLY COLD TEMPERATURES FOR ALASKA. THE PATTERN MAY LEAD TO
HIGH WINDS ACROSS SOUTHERN ALASKA, LEADING TO DANGEROUSLY LOW WIND CHILLS. AS A
POSSIBLY STRONG SURFACE LOW FROM THE END OF WEEK-1 DEPARTS THE NORTHEAST AT THE
BEGINNING OF WEEK-2, THERE IS ENHANCED RISK OF HIGH WINDS FOR THE NORTHEASTERN
CONUS.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION FOR THE PACIFIC NORTHWEST, MON, DEC 30.
MODERATE RISK OF HEAVY SNOW FOR THE CASCADES, TUE-MON, DEC 30-JAN 5.
MODERATE RISK OF HEAVY SNOW FOR THE KLAMATH MOUNTAINS AND SIERRA NEVADA,
THU-SAT, JAN 1-3.
SLIGHT RISK OF HEAVY PRECIPITATION FOR THE PACIFIC NORTHWEST AND CENTRAL AND
NORTHERN CALIFORNIA, TUE-MON, DEC 30-JAN 5.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADES, KLAMATH, AND SIERRA NEVADA
MOUNTAINS, TUE-MON, DEC 30-JAN 5.
MODERATE RISK OF HEAVY SNOW FOR THE NORTHERN ROCKIES AND PART OF THE NORTHERN
INTERMOUNTAIN WEST, TUE-MON, DEC 30-JAN 5.
SLIGHT RISK OF HEAVY SNOW FOR THE HIGHER ELEVATIONS OF THE INTERIOR WEST,
TUE-MON, DEC 30-JAN 5.
MODERATE RISK OF HIGH WINDS FOR PARTS OF THE WEST, TUE-MON, DEC 30-JAN 5.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF THE WEST, GREAT PLAINS, AND UPPER
MISSISSIPPI VALLEY, TUE-MON, DEC 30-JAN 5.
SLIGHT RISK OF HIGH WINDS FOR THE NORTHEAST AND NORTHERN PORTIONS OF THE
MID-ATLANTIC, TUE-WED, DEC 30-DEC 31.
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR MUCH OF SOUTHERN MAINLAND
AND SOUTHEAST ALASKA, TUE, DEC 30 AND FRI-MON, JAN 2-5.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR SOUTHERN AND CENTRAL MAINLAND
AND SOUTHEAST ALASKA, TUE-MON, DEC 30-JAN 5.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF SOUTHERN ALASKA, INCLUDING THE ALASKA
RANGE, TUE-MON, DEC 30-JAN 5.
FLOODING POSSIBLE FOR PARTS OF NORTHERN CALIFORNIA AND THE PACIFIC NORTHWEST.
DETAILED SUMMARY
FOR THURSDAY DECEMBER 25 - MONDAY DECEMBER 29:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY DECEMBER 30 - MONDAY JANUARY 05: THE ECENS, GEFS, AND CMCE CONTINUE
TO BE IN GOOD AGREEMENT AND HAVE GOOD RUN-TO-RUN CONSISTENCY INDICATING AN
ANOMALOUS 500-HPA RIDGE (TROUGH) PERSISTING OVER THE BERING SEA (NORTHEASTERN
PACIFIC) THROUGHOUT WEEK-2. THE AMPLIFIED NORTHEASTERN PACIFIC TROUGH FAVORS A
RETURN OF AN ATMOSPHERIC RIVER (AR) TO THE PACIFIC NORTHWEST. EARLY IN WEEK-2,
THE ECENS DEPICTS LARGE INCREASED PROBABILITIES FOR ENHANCED INTEGRATED VAPOR
TRANSPORT (IVT) VALUES INITIALLY IMPACTING THE PACIFIC NORTHWEST AND SHIFTING
SOUTHWARD THROUGH WEEK-2. AREAS OF HIGH RISK FOR HEAVY PRECIPITATION AND/OR
HEAVY SNOW TIME OFF BEFORE THE PERIOD. AREAS OF MODERATE RISK FOR HEAVY
PRECIPITATION FOR THE PACIFIC NORTHWEST, DEC 30, AND HEAVY SNOW FOR THE
CASCADES THROUGHOUT WEEK-2, CONTINUE TO BE DESIGNATED BASED ON UNCALIBRATED
MODEL GUIDANCE. A MODERATE RISK IS HIGHLIGHTED FOR THE KLAMATH MOUNTAINS AND
SIERRA NEVADA THE MIDDLE OF WEEK-2, AS THE ENHANCED MOIST FLOW SHIFTS SOUTHWARD
GIVEN INCREASED SIGNAL IN THE IVT AND UNCALIBRATED TOOLS. THE SLIGHT RISK AREA
IS EXPANDED TO INCLUDE PORTIONS OF CENTRAL CALIFORNIA IN ADDITION TO NORTHERN
CALIFORNIA AND THE PACIFIC NORTHWEST THROUGHOUT THE PERIOD GIVEN INCREASES IN
IVT SIGNAL FURTHER SOUTH COMPARED TO YESTERDAY. GIVEN THE ONGOING RIVER
FLOODING AND SATURATED SOILS ALONG WITH HEAVY PRECIPITATION FORECAST IN THE
NEXT WEEK, A POSSIBLE FLOODING HAZARD, WITH AN ASSOCIATED RISK OF LANDSLIDES
AND DEBRIS FLOWS IN STEEP TERRAIN OR BURN SCARS, REMAINS POSTED FOR PARTS OF
THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA.
THE AMPLIFIED 500-HPA TROUGH UPSTREAM AND MODEL GUIDANCE FAVOR A SLIGHT TO
MODERATE RISK OF HEAVY SNOW THROUGHOUT WEEK-2 FROM THE NORTHERN ROCKIES SOUTH
TO THE HIGHER ELEVATIONS OF UTAH AND COLORADO. THE LARGE SPATIAL EXTENT OF
HAZARDOUS SNOW IS SUPPORTED BY THE GEFS SWE PET AND ALSO CONSISTENT WITH THE
WEEK-2 OUTLOOK HAVING A 40-50% CHANCE OF ABOVE-NORMAL PRECIPITATION ACROSS THE
WEST. A MODERATE RISK OF HEAVY SNOW REMAINS FOCUSED ON THE NORTHERN ROCKIES
WHERE THE HEAVIEST SNOWFALL IS PREDICTED.
THE LONGWAVE PATTERN AND ENHANCED PACIFIC FLOW SUPPORT PERIODS OF HIGH WINDS
ACROSS MUCH OF THE WEST THROUGHOUT WEEK-2. A MODERATE RISK FOR HIGH WINDS IS
DESIGNATED FROM THE COASTAL PACIFIC NORTHWEST AND NORTHERN CALIFORNIA EAST TO
THE NORTHERN AND CENTRAL ROCKIES, INCLUDING THE COLORADO FRONT RANGE. FARTHER
EAST, INDIVIDUAL SHORTWAVES ARE ANTICIPATED TO PERIODICALLY BE EJECTED
EASTWARD, INDUCING ONE OR MORE SURFACE LOWS OVER THE GREAT PLAINS. THEREFORE, A
SLIGHT RISK OF HIGH WINDS IS POSTED FOR MUCH OF THE GREAT PLAINS AND UPPER
MISSISSIPPI VALLEY.
AS A POTENTIALLY STRONG SURFACE LOW EXITS THE NORTHEAST AT THE BEGINNING OF
WEEK-2, ENHANCED WINDS COULD LINGER FROM THE END OF WEEK-1 FOR THE NORTHEASTERN
CONUS. A SLIGHT RISK OF HIGH WINDS ARE DESIGNATED FOR PORTIONS OF THE NORTHEAST
AND NORTHERN PORTIONS OF THE MID-ATLANTIC DEC 30-31. THE ECENS PET SHOWS AT
LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE
CLIMATOLOGICALLY AND 20 MPH, FURTHER SUPPORTED BY RECENT DETERMINISTIC MODELS
AND UNCALIBRATED ENSEMBLE GUIDANCE.
ARCTIC HIGH PRESSURE IS LIKELY TO PERSIST OVER ALASKA INTO THE NEW YEAR. THE
RISK OF MUCH BELOW NORMAL TEMPERATURES EXPECTED INITIALLY TO BE MOST LIKELY
ACROSS EASTERN ALASKA, EXPANDING WESTWARD DURING WEEK-2. A BRIEF EASING OF THE
ANOMALOUS COLD IS EXPECTED DECEMBER 31 TO JANUARY 1, BEFORE BUILDING BACK AGAIN
BY JANUARY 2. THEREFORE A MODERATE RISK IS DESIGNATED FOR THESE DATES FOR MUCH
OF SOUTHERN MAINLAND AND SOUTHEAST ALASKA. THE SLIGHT RISK GOES THROUGH THE
ENTIRETY OF WEEK-2 AND INCLUDES ALL OF ALASKA SOUTH OF THE BROOKS RANGE. WITH
HIGH PRESSURE OVER THE YUKON AND SURFACE LOW PRESSURE OVER THE GULF OF ALASKA,
A TIGHT PRESSURE GRADIENT MAY LEAD TO HIGH WINDS (GAP WINDS FOR THE
SOUTHEASTERN MAINLAND AND SOUTHEAST ALASKA), SUPPORTING A SLIGHT RISK OF HIGH
WINDS FOR THE ALEUTIANS AND SOUTHERN ALASKA. THE PETS (ESPECIALLY THE ECENS)
INDICATE AT LEAST A 20% CHANCE OF WIND SPEEDS EXCEEDING THE 85TH PERCENTILE AND
40 MPH. THE VERY COLD WEATHER AND HIGH WINDS ALONG THE SOUTHERN TIER OF THE
STATE INCREASES THE THREAT FOR HEAVY FREEZING SPRAY AT TIMES IN MARINE AREAS IN
ADDITION TO HAZARDOUS LOW WIND CHILLS POSSIBLE, IMPACTING VULNERABLE
POPULATIONS. ADDITIONALLY, THIS PATTERN MAY BE CONDUCIVE TO HEAVY PRECIPITATION
LINGERING FROM THE END OF WEEK-1 INTO THE ONSET OF WEEK-2, RESULTING IN A
SLIGHT RISK OF HEAVY SNOW FOR NORTHERN PORTIONS OF SOUTHEAST ALASKA (THE
PANHANDLE) AND HEAVY PRECIPITATION (MORE LIKELY RAINFALL) ACROSS SOUTHERN
PORTIONS, DECEMBER 30.
A STORM SYSTEM IS PREDICTED TO FORM IN THE CENTRAL PACIFIC BY THE START OF
WEEK-2, WHICH COULD APPROACH HAWAII. THIS WOULD INCREASE CHANCES FOR
ABOVE-NORMAL PRECIPITATION INITIALLY FOR THE WESTERN ISLANDS SHIFTING EASTWARD
WITH TIME. SOME AREAS MAY HAVE INCREASED LIKELIHOOD OF HEAVY PRECIPITATION
DURING WEEK-2.
FORECASTER: MELISSA OU
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