536
FXUS21 KWNC 261953
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST DECEMBER 26 2025
SYNOPSIS: CONTINUED MID-LEVEL HIGH PRESSURE OVER EASTERN SIBERIA AND MID-LEVEL
LOW PRESSURE OVER THE GULF OF ALASKA IS FAVORED TO KEEP VERY COLD AIR IN PLACE
OVER MUCH OF ALASKA, WHILE STRONG PRESSURE CONTRASTS AT THE SURFACE BETWEEN THE
WARMER OCEAN AND THE FRIGID INTERIOR PROMOTE STRONG WINDS ALONG THE SOUTHERN
AND SOUTHEASTERN COAST OF ALASKA. MOIST ONSHORE FLOW PERSISTS OVER THE WEST
COAST, BRINGING POTENTIALLY HEAVY RAIN AND SNOW AND HIGH WINDS TO MUCH OF THE
WESTERN CONTIGUOUS U.S. (CONUS). EARLY IN WEEK-2 A SURFACE LOW PRESSURE SYSTEM
IS FAVORED TO MOVE OVER NEW ENGLAND, USHERING IN POTENTIALLY HAZARDOUS COLD
CONDITIONS.
HAZARDS
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR SOUTHWESTERN MAINLAND
ALASKA, THE ALASKA PENINSULA, AND EASTERN ALEUTIANS, SAT-MON, JAN 3-5.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR ALL OF ALASKA WITH THE
EXCEPTION OF THE NORTH SLOPE AND SOUTHEAST ALASKA, SAT-WED, JAN 3-7.
SLIGHT RISK OF HIGH WINDS FOR THE ALASKA PENINSULA, SOUTHERN MAINLAND ALASKA,
AND SOUTHEASTERN ALASKA, SAT-WED, JAN 3-7.
SLIGHT RISK OF HEAVY SNOW FOR THE CASCADES, KLAMATH, AND SIERRA NEVADAS,
SAT-WED, JAN 3-7.
SLIGHT RISK OF HEAVY SNOW FOR PORTIONS OF THE UPPER MISSISSIPPI VALLEY AND
WESTERN GREAT LAKES, SAT-MON, JAN 3-5.
SLIGHT RISK OF HEAVY PRECIPITATION FOR CALIFORNIA SOUTH OF SAN FRANCISCO BAY
AND MUCH OF THE DESERT SOUTHWEST, SAT-SUN, JAN 3-4.
SLIGHT RISK OF HEAVY PRECIPITATION FOR NORTHERN CALIFORNIA, AND WESTERN OREGON
AND WASHINGTON, SUN-TUE, JAN 4-6.
SLIGHT RISK OF HEAVY PRECIPITATION FOR PORTIONS OF THE TENNESSEE AND LOWER
MISSISSIPPI VALLEYS AND SOUTHEASTERN U.S., SAT-MON, JAN 3-5.
SLIGHT RISK OF HIGH WINDS ALONG THE CALIFORNIA COAST SOUTH OF CAPE MEDONCINO,
SAT-SUN, JAN 3-4.
SLIGHT RISK OF HIGH WINDS FOR WESTERN PORTIONS OF THE SOUTHERN AND CENTRAL
PLAINS, SAT-MON, JAN 3-5.
DETAILED SUMMARY
FOR MONDAY DECEMBER 29 - FRIDAY JANUARY 02:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JANUARY 03 - FRIDAY JANUARY 09: TODAY'S MODEL SOLUTIONS ARE IN
RATHER POOR AGREEMENT REGARDING THE SYNOPTIC PATTERN AS DEPICTED BY 500-HPA
HEIGHT ANOMALIES OVER THE NORTH PACIFIC AND NORTH AMERICA, WITH EVER-INCREASING
MODEL SPREAD RELATING TO THE PLACEMENT OF KEY SYNOPTIC FEATURES AS THE FORECAST
PERIOD PROGRESSES. EARLY IN WEEK-2 ENSEMBLE SOLUTIONS DEPICT RIDGING OVER THE
BERING SEA, TROUGHING OVER THE WEST COAST, WEAK RIDGING OVER THE MISSISSIPPI
VALLEY, AND AMPLIFIED TROUGHING OVER THE CANADIAN MARITIMES. MODELS THEN
DIVERGE QUICKLY, WITH THE GEFS MAINTAINING A STRONG RIDGE OVER THE BERING SEA
WHILE THE ECMWF AND CMCE FAVOR A WEAKER RIDGE SHIFTED SOUTHWARD INTO THE NORTH
PACIFIC, AND THERE IS NO CONSENSUS WITH REGARD TO THE EVOLUTION OF THE
DOWNSTREAM TROUGH. AS SUCH, FORECAST CONFIDENCE IS RATHER LOW AND RELIES TO
SOME EXTENT ON PERSISTENCE.
AT THE SURFACE, HIGH PRESSURE PERSISTS 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 THROUGH THE
MIDDLE OF THE PERIOD. THERE IS STILL SOME SIGNAL FOR HIGH WINDS AT THE END OF
WEEK-2, BUT GIVEN INCREASING MODEL SPREAD THERE IS INSUFFICIENT CONFIDENCE TO
ISSUE A FULL-WEEK HAZARD. THEREFORE A SLIGHT RISK OF HIGH WINDS IS POSTED FOR
MOST OF SOUTHERN AND SOUTHEASTERN ALASKA FOR JAN 3-7.
PETS CONTINUE TO HIGHLIGHT ENHANCED CHANCES FOR TEMPERATURES TO FALL TO NEAR
HAZARDOUS THRESHOLDS ACROSS MUCH OF SOUTHERN, INTERIOR, AND SOUTHEAST ALASKA,
DRIVEN IN PART BY THE PRESSURE GRADIENT DISCUSSED ABOVE. A MODERATE RISK OF
MUCH BELOW-NORMAL TEMPERATURES IS POSTED FOR SOUTHERN ALASKA WEST OF PRINCE
WILLIAMS SOUND, THE LOWER YUKON, AND THE ALASKAN PENINSULA, VALID JAN 3-5,
WHILE A BROADER SLIGHT RISK IS POSTED FOR ALL OF THE ALASKAN MAINLAND WITH THE
EXCEPTION OF THE NORTH SLOPE AND SOUTHEAST ALASKA FOR JAN 3-7. TODAY'S FORECAST
HAS SHIFTED THESE HAZARDS WESTWARD AS MODELS INDICATE THE POTENTIAL BREAKDOWN
OF THE BLOCKING SIBERIAN RIDGE, PUSHING THE COLDEST AIR FURTHER WEST. 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 THROUGHOUT THE FORECAST PERIOD. THE INTEGRATED
VAPOR TRANSPORT (IVT) TOOL ALSO INDICATES MODERATE LOW-LEVEL MOISTURE RESUMING
BY THE MIDDLE OF THE FORECAST PERIOD AFTER A BRIEF BREAK LATE IN WEEK-1, WITH
BOTH THE ECMWF AND GEFS SHOWING PROBABILITIES ABOVE 40% FOR IVT TO EXCEED 150
KG/M/S BY DAY-10 (JAN 5). TODAY'S FORECAST SOLUTIONS INITIALLY PLACE THE
HEAVIEST PRECIPITATION OVER THE SOUTHWESTERN CONUS, THEN GRADUALLY SHIFT BACK
NORTH OVER THE PACIFIC NORTHWEST. THE PETS AND UNCALIBRATED PRECIPITATION
GUIDANCE SUPPORTS A SLIGHT RISK OF HEAVY PRECIPITATION FOR CALIFORNIA SOUTH OF
THE GOLDEN GATE AS WELL AS MUCH OF THE DESERT SOUTHWEST FOR JAN 3-4, AS WELL AS
A SLIGHT RISK FOR NORTHERN CALIFORNIA, AND WESTERN OREGON AND WASHINGTON FOR
JAN 4-6.
THE INCOMING MOISTURE ASSOCIATED WITH THIS ATMOSPHERIC RIVER (AR) IS LIKELY TO
PUSH INLAND, RESULTING IN POTENTIALLY HEAVY SNOW FOR MANY OF THE COASTAL RANGES
ALONG THE WEST COAST. UNCALIBRATED PROBABILITIES FROM BOTH THE ECENS AND GEFS
FOR DAILY ACCUMULATIONS OF OVER 6 INCHES EXCEED 40% IN SOME LOCATIONS
THROUGHOUT 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 AND SIERRAS DURING VARIOUS
PORTIONS OF WEEK-2. BASED ON THE GEFS PET AND UNCALIBRATED DAILY SNOWFALL
TOTALS, A SLIGHT RISK OF HEAVY SNOW IS POSTED JAN 3-7 FOR THE CASCADES,
KLAMATH, AND NORTHERN SIERRAS.
ALONG WITH HEAVY PRECIPITATION AND SNOW, HIGH WINDS REACHING HAZARDOUS CRITERIA
ARE ALSO POSSIBLE ASSOCIATED WITH THIS AR EVENT. MODEL ENSEMBLE MAXIMUM WIND
SPEEDS FROM THE ECMWF AND GEFS EXCEED 20MPH ALONG THE CALIFORNIA COAST SOUTH OF
CAPE MENDOCINO DURING THE FIRST HALF OF WEEK-2, WARRANTING A SLIGHT RISK OF
HIGH WIND ALONG THE COAST COVERING THE PERIOD JAN 3-4. FURTHER INLAND, SURFACE
LOW PRESSURE IN THE LEE OF THE ROCKIES EARLY IN THE FORECAST PERIOD IS FAVORED
TO ENHANCE WINDS OVER PORTIONS OF THE GREAT PLAINS. BASED ON ENSEMBLE MEAN WIND
SPEEDS FROM THE GEFS AND ECMWF, A SLIGHT RISK OF HIGH WINDS IS POSTED FOR
WESTERN PORTIONS OF THE SOUTHERN AND CENTRAL PLAINS, ALSO FOR JAN 3-5. GIVEN A
LACK OF ANTECEDENT RAIN AND/OR SNOW, FUELS ARE UNUSUALLY DRY, ELEVATING THE
POTENTIAL FOR PRAIRIE FIRES.
THE LEE CYCLOGENESIS DISCUSSED ABOVE IS ALSO FAVORED TO INDUCE ENHANCED
PRECIPITATION AHEAD OF THE DEVELOPING SURFACE LOW PRESSURE. THE GEFS AND ECMWF
PETS BOTH INDICATE AT LEAST A 20% CHANCE OF 3-DAY PRECIPITATION TOTALS TO
EXCEED THE 85TH PERCENTILE AND AT LEAST 1-INCH FOR MUCH OF THE SOUTHEASTERN
CONUS EARLY IN WEEK-2. POTENTIALLY HEAVY SNOW IS ALSO DEPICTED FURTHER NORTH,
WITH UNCALIBRATED PROBABILITIES FROM THE ECMWF AND GEFS INDICATING AT LEAST A
20% CHANCE OF SNOWFALL ACCUMULATIONS TO EXCEED 4 INCHES, ALTHOUGH THERE IS
LARGE SPREAD WITH REGARD TO THE WESTERN EXTENT OF THE HEAVIEST SNOWFALL. BASED
ON THE BEST MODEL CONSENSUS, A SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED FOR
PORTIONS OF THE TENNESSEE AND LOWER MISSISSIPPI VALLEYS, AND SOUTHEAST U.S. FOR
JAN 3-5, AND A SLIGHT RISK OF HEAVY SNOW FOR PORTIONS OF THE UPPER MISSISSIPPI
VALLEY AND WESTERN GREAT LAKES, ALSO VALID JAN 3-5.
FORECASTER: DANNY BARANDIARAN
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