647
FXUS21 KWNC 112051
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST DECEMBER 11 2025
SYNOPSIS: STRONG MID-LEVEL AND SURFACE LOW PRESSURE OVER THE NORTH PACIFIC
BRING THE POTENTIAL FOR A VARIETY OF HAZARDOUS WEATHER INCLUDING HAZARDOUS COLD
ACROSS SOUTHERN ALASKA, AND HIGH WINDS, HEAVY PRECIPITATION, AND HIGH-ELEVATION
SNOW ACROSS THE WESTERN CONTIGUOUS U.S. (CONUS) THROUGHOUT THE WEEK-2 PERIOD.
SURFACE LOW PRESSURE OVER THE GREAT PLAINS ALONG WITH SURFACE HIGH PRESSURE
OVER THE SOUTHEAST U.S. PAIR TO PRODUCE POTENTIALLY HAZARDOUS WINDS OVER MUCH
OF THE PLAINS, UPPER MISSISSIPPI VALLEY, AND GREAT LAKES. STRONG SURFACE HIGH
PRESSURE OVER THE YUKON IS FAVORED TO PUSH EXTREMELY COLD AIR INTO SOUTHEASTERN
ALASKA, POTENTIALLY BELOW HAZARDOUS CRITERIA.
HAZARDS
HIGH RISK OF HEAVY SNOW FOR THE NORTHERN SIERRA NEVADAS, KLAMATH, AND OREGON
CASCADES, FRI-SUN, DEC 19-21.
MODERATE RISK OF HEAVY SNOW FOR THE CASCADES, KLAMATH, AND NORTHERN AND CENTRAL
SIERRA NEVADAS, FRI-MON, DEC 19-22.
MODERATE RISK OF HEAVY SNOW FOR THE NORTHERN ROCKIES, FRI-MON, DEC 19-22.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADES, KLAMATH, AND SIERRA NEVADAS,
FRI-THU, DEC 19-25.
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN AND CENTRAL ROCKIES, THE WASATCH,
AND THE NORTHEASTERN BASIN AND RANGE, FRI-THU, DEC 19-25.
HIGH RISK OF HEAVY PRECIPITATION FOR COASTAL PORTIONS OF NORTHWESTERN
CALIFORNIA AND SOUTHWESTERN OREGON, FRI-SUN, DEC 19-21.
MODERATE RISK OF HEAVY PRECIPITATION OF PORTIONS OF NORTHERN CALIFORNIA AND
COASTAL PORTIONS OF OREGON AND WASHINGTON, FRI-MON, DEC 19-22.
SLIGHT RISK OF HEAVY PRECIPITATION ALONG THE ENTIRE WEST COAST, FRI-THU, DEC
19-25.
MODERATE RISK OF HIGH WINDS FOR MUCH OF NORTHERN CALIFORNIA, THE PACIFIC
NORTHWEST, NORTHERN GREAT BASIN, AND NORTHERN ROCKIES, FRI-SUN, DEC 19-21.
SLIGHT RISK OF HIGH WINDS FOR MUCH OF CALIFORNIA, PACIFIC NORTHWEST, GREAT
BASIN, NORTHERN ROCKIES, NORTHERN AND CENTRAL PLAINS, MIDDLE AND UPPER
MISSISSIPPI VALLEY, AND GREAT LAKES, FRI-THU, DEC 19-25.
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR SOUTHEASTERN ALASKA,
FRI-TUE, DEC19-23.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR MUCH OF SOUTH-CENTRAL AND
SOUTHEASTERN ALASKA, FRI-THU, DEC 19-25.
FLOODING POSSIBLE FOR PORTIONS OF THE PACIFIC NORTHWEST AND NORTHERN CALIFORNIA.
DETAILED SUMMARY
FOR SUNDAY DECEMBER 14 - THURSDAY DECEMBER 18:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY DECEMBER 19 - THURSDAY DECEMBER 25: THE 0Z ECWMF, GEFS, AND CANADIAN
ENSEMBLES DEPICT AN AMPLIFIED MID-LEVEL RIDGE CENTERED OVER THE BERING SEA,
WITH AN AMPLIFIED DOWNSTREAM MID-LEVEL TROUGH ESTABLISHED OVER SOUTHEAST
ALASKA. AT THE SURFACE, THIS SET-UP FAVORS PERSISTENT HIGH PRESSURE ACROSS MUCH
OF ALASKA AND THE YUKON THROUGHOUT WEEK-2. CONVERSELY, MEAN LOW PRESSURE IS
FAVORED IN THE GULF OF ALASKA. THE PRESSURE GRADIENT BETWEEN THESE FEATURES
BRINGS INCREASED CHANCES FOR EPISODES OF HIGH WINDS ACROSS MUCH OF SOUTHERN
ALASKA FROM THE CENTRAL ALEUTIAN ISLANDS THROUGH SOUTHEAST ALASKA. HIGH WINDS
WOULD BE PARTICULARLY FAVORED IN GAPS AND INLETS. PROBABILISTIC EXTREMES TOOLS
(PETS) SHOW ENHANCED CHANCES OF WIND SPEEDS EXCEEDING THE 85TH CLIMATOLOGICAL
PERCENTILE. THEREFORE, A SLIGHT RISK OF HIGH WINDS IS POSTED FOR MOST OF
SOUTHERN AND SOUTHEASTERN ALASKA FOR ALL OF WEEK-2.
PETS CONTINUE TO HIGHLIGHT ENHANCED CHANCES FOR TEMPERATURES TO FALL TO NEAR
HAZARDOUS THRESHOLDS ACROSS PORTIONS OF SOUTH-CENTRAL, INTERIOR, AND SOUTHEAST
ALASKA. AS THE BERING SEA RIDGE SLOWLY WEAKENS, THE ANOMALOUS COLD (AND
ASSOCIATED NORTHERLY FLOW) WILL GRADUALLY EXPAND WESTWARD ACROSS THE STATE. A
MODERATE RISK IS POSTED FOR SOUTHEAST ALASKA FOR DEC 19-23, WHILE A BROADER
SLIGHT RISK IS MAINTAINED FOR MUCH OF SOUTH-CENTRAL AND SOUTHEAST ALASKA FOR
ALL OF WEEK-2. TEMPERATURES BETWEEN -20 DEG F AND -35 DEG F ARE PREDICTED TO BE
WIDESPREAD ACROSS MUCH OF INLAND ALASKA, WITH -40 DEG F TEMPERATURES INDICATED
BY THE PETS OVER THE EASTERN INTERIOR TO THE NORTH OF FAIRBANKS. CLOSER TO THE
COAST, TEMPERATURES ARE EXPECTED TO RANGE BETWEEN 0 AND -15 DEG F (ANCHORAGE
NEAR -10 DEG F), WHILE THE SOUTHERN HALF OF SOUTHEAST ALASKA IS PREDICTED TO BE
SOMEWHAT MILDER, WITH HIGH TEMPERATURES ABOUT +10 DEG F. THE COMBINATION OF
VERY COLD WEATHER AND HIGH WINDS ALONG THE SOUTHERN TIER OF THE STATE INCREASES
THE THREAT FOR HEAVY FREEZING SPRAY AT TIMES NEAR LARGER BODIES OF WATER.
THE 0Z ECENS, 0Z GEFS, AND 0Z CMCE MODEL SOLUTIONS DEPICT PERSISTENT MID-LEVEL
TROUGHING OVER THE NORTH PACIFIC AND BROAD POSITIVE 500-HPA HEIGHT ANOMALIES
ACROSS MUCH OF THE SOUTHERN CONUS, RESULTING IN AN ENHANCED JET STREAM OVER THE
PACIFIC NORTHWEST. THE INTEGRATED VAPOR TRANSPORT (IVT) TOOL ALSO INDICATES
DEEP LOW-LEVEL MOISTURE STREAMING INTO THE WEST COAST THROUGHOUT THE FORECAST
PERIOD, WITH BOTH THE ECMWF AND GEFS SHOWING PROBABILITIES EXCEEDING 40% FOR
IVT TO EXCEED 250 KG/M/S, ESPECIALLY EARLY IN WEEK-2.
THE PETS AND UNCALIBRATED PRECIPITATION GUIDANCE SUPPORTS A SLIGHT RISK OF
HEAVY PRECIPITATION ALONG ALL OF THE WEST COAST FOR DEC 19-25. A MODERATE RISK
FOR HEAVY PRECIPITATION IS INDICATED FOR THE PACIFIC NORTHWEST, NORTHERN AND
PORTIONS OF CENTRAL CALIFORNIA FROM DEC 19-22. ADDITIONALLY, A HIGH RISK OF
HEAVY PRECIPITATION IS POSTED FOR SOUTHWESTERN OREGON AND NORTHWESTERN
CALIFORNIA, ALSO VALID FROM DEC 19-21. PRECIPITATION AMOUNTS OF 2 INCHES ARE
PREDICTED BY PET GUIDANCE WITHIN THIS BROAD REGION OF ELEVATED ONSHORE FLOW
FROM WASHINGTON STATE SOUTHWARD TO CENTRAL CALIFORNIA. NEAR AN INCH OF
PRECIPITATION IS INDICATED AS FAR SOUTH AS THE LOS ANGELES AREA. THIS
FORECASTED HEAVY PRECIPITATION, IN ADDITION TO THE ANTECEDENT WEEK-1
PRECIPITATION, IS LIKELY TO AGGRAVATE FLOODING ISSUES FOR THE PACIFIC
NORTHWEST, WITH A FLOODING POSSIBLE HAZARD REMAINING POSTED AND EXTENDED INTO
NORTHWESTERN CALIFORNIA. CONTINUED PRECIPITATION ACCUMULATIONS ON SATURATED
SOILS BRINGS THE ADDITIONAL RISKS OF LANDSLIDES AND DEBRIS FLOWS IN STEEP
TERRAIN OR BURN SCARS.
THE INCOMING MOISTURE ASSOCIATED WITH THIS ATMOSPHERIC RIVER IS LIKELY TO PUSH
WELL INLAND, RESULTING IN POTENTIALLY HEAVY SNOW FOR MANY MOUNTAIN RANGES
ACROSS THE WEST. UNCALIBRATED PROBABILITIES FROM BOTH THE ECENS AND GEFS FOR
DAILY ACCUMULATIONS OF OVER 6 INCHES EXCEED 40% IN SOME LOCATIONS ESPECIALLY
EARLY IN THE WEEK, AND THE GEFS PET FOR SNOW WATER EQUIVALENT (SWE) INDICATES
AT LEAST A 20% CHANCE OF 3-DAY SWE TO EXCEED THE 85TH CLIMATOLOGICAL PERCENTILE
AND AT LEAST 1 INCH FOR MUCH OF THE CASCADES, SIERRAS, AND NORTHERN AND CENTRAL
ROCKIES THROUGHOUT THE WEEK. BASED ON THE GEFS PET AND UNCALIBRATED DAILY
SNOWFALL TOTALS, A HIGH RISK OF HEAVY SNOW IS POSTED FOR THE OREGON CASCADES,
NORTHERN SIERRA NEVADAS, AND PORTIONS OF THE KLAMATH FOR DEC 19-21. THERE IS A
MODERATE RISK OF HEAVY SNOW FOR DEC 19-22 FOR THE CASCADES, KLAMATH, AND
NORTHERN AND CENTRAL SIERRAS, AND A SLIGHT RISK OF HEAVY SNOW FOR THE CASCADES,
KLAMATH, AND SIERRA NEVADAS FOR ALL OF WEEK-2. FURTHER EAST, A MODERATE RISK OF
HEAVY SNOW IS POSTED FOR MUCH OF THE NORTHERN ROCKIES FOR DEC 19-22, AND A
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN AND CENTRAL ROCKIES, THE WASATCH,
AND NORTHEASTERN BASIN AND RANGE FOR ALL OF WEEK-2.
ALONG WITH HEAVY PRECIPITATION AND SNOW, HIGH WINDS REACHING HAZARDOUS CRITERIA
ARE ALSO POSSIBLE ASSOCIATED WITH THIS ATMOSPHERIC RIVER (AR) EVENT. THIS IS
WELL INDICATED BY THE ECMWF AND GEFS PETS WHICH INDICATE AT LEAST A 20% CHANCE
OF 3-DAY MAXIMUM WIND SPEEDS EXCEEDING THE 85TH PERCENTILE FOR MUCH OF THE
CONUS THROUGHOUT THE WEEK. OVER THE WESTERN CONUS, ENHANCED WINDS ARE LIKELY
THE RESULT OF DEEP TROUGHING AND AR OVER THE WEST COAST, WHILE PERIODS OF
SURFACE LOW PRESSURE OVER THE PLAINS AND HIGH PRESSURE OVER THE SOUTHEAST U.S.
ARE THE FEATURES ENHANCING WINDS ELSEWHERE. A SLIGHT RISK OF HIGH WINDS IS
POSTED FOR MOST OF THE WESTERN CONUS AS WELL AS THE NORTHERN AND CENTRAL PLAINS
AND GREAT LAKES REGIONS FOR ALL OF WEEK-2. THE ECMWF PET IS ESPECIALLY BULLISH,
WITH PROBABILITIES EXCEEDING 80% FOR MUCH OF THE NORTHWESTERN CONUS EARLY IN
WEEK-2, FURTHER BACKED BY PATTERN RECOGNITION, WARRANTING A MODERATE RISK OF
HIGH WINDS FOR MUCH OF THE PACIFIC NORTHWEST, NORTHERN GREAT BASIN, AND
NORTHERN ROCKIES FOR DEC 19-21.
FORECASTER: DANNY BARANDIARAN
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