901
FXUS21 KWNC 022049
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST DECEMBER 02 2025
SYNOPSIS: MID-LEVEL LOW PRESSURE ACROSS THE NORTHEASTERN PACIFIC AND ALASKA
ALONG WITH MID-LEVEL HIGH PRESSURE FURTHER WEST ARE EXPECTED TO KEEP VERY COLD
AIR ACROSS CENTRAL AND SOUTHERN MAINLAND ALASKA ALONG WITH EPISODES OF HIGH
WINDS ACROSS SOUTHERN ALASKA FROM THE ALEUTIANS INTO SOUTHEASTERN ALASKA. THIS
MID-LEVEL LOW PRESSURE AND AN AMPLIFYING MID-LEVEL RIDGE FARTHER SOUTH SHOULD
ENHANCE MOIST PACIFIC FLOW ACROSS THE NORTHWESTERN CONUS, BRINGING RISKS OF
HEAVY PRECIPITATION, HEAVY HIGH-ELEVATION SNOW, AND HIGH WINDS TO THE REGION
EARLY WEEK-2. MID-LEVEL LOW PRESSURE IS ALSO FORECAST ACROSS THE EASTERN U.S.,
RESULTING IN UNSETTLED WEATHER THAT MAY INCLUDE HEAVY SNOW WITH LAKE-EFFECT
SQUALLS ACROSS PORTIONS OF THE GREAT LAKES, NORTHEAST, AND CENTRAL
APPALACHIANS, BUT SPECIFIC AMOUNTS, TIMING, AND LOCATIONS AFFECTED ARE
UNCERTAIN.
HAZARDS
MODERATE RISK OF HEAVY PRECIPITATION ACROSS WESTERN WASHINGTON AND NORTHWESTERN
OREGON, WED-THU, DEC 10-11.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS MUCH OF THE PACIFIC NORTHWEST,
NORTHERN INTERMOUNTAIN WEST, AND NORTHERN ROCKIES, WED-FRI, DEC 10-12.
MODERATE RISK OF HEAVY SNOW ACROSS THE NORTHERN CASCADES, WED-THU, DEC 10-11.
SLIGHT RISK OF HEAVY SNOW ACROSS THE CASCADES, WED-FRI, DEC 10-12.
SLIGHT RISK OF HEAVY SNOW ACROSS THE NORTHERN ROCKIES AND ADJACENT HIGH PLAINS,
WED-FRI, DEC 10-12.
SLIGHT RISK OF HEAVY SNOW ACROSS THE UPPER PENINSULA OF MICHIGAN AND WESTERN
PORTIONS OF LOWER MICHIGAN, WED-THU, DEC 10-11.
SLIGHT RISK OF HEAVY SNOW ACROSS PORTIONS OF THE INTERIOR NORTHEAST AND CENTRAL
APPALACHIANS, INCLUDING THE LEE OF LAKES ERIE AND ONTARIO, WED-THU, DEC 10-11.
MODERATE RISK OF HIGH WINDS ACROSS MUCH OF THE PACIFIC NORTHWEST, NORTHERN
GREAT BASIN, NORTHERN ROCKIES, AND NORTHERN HIGH PLAINS, WED-THU, DEC 10-11.
SLIGHT RISK OF HIGH WINDS ACROSS THE NORTHWESTERN CONUS INTO THE NORTHERN AND
CENTRAL HIGH PLAINS, WED-FRI, DEC 10-12.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS MOST OF CENTRAL AND
SOUTHERN MAINLAND ALASKA, WED-SAT, DEC 10-13.
SLIGHT RISK OF HIGH WINDS ACROSS SOUTHERN ALASKA FROM SOUTHEAST ALASKA THROUGH
MUCH OF THE ALEUTIANS, WED-TUE, DEC 10-16.
FLOODING POSSIBLE ACROSS THE PACIFIC NORTHWEST.
DETAILED SUMMARY
FOR FRIDAY DECEMBER 05 - TUESDAY DECEMBER 09:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY DECEMBER 10 - TUESDAY DECEMBER 16: THE 0Z ECWMF, GEFS, AND
CANADIAN ENSEMBLES ALL DEPICT ANOMALOUS 500-HPA TROUGHING ACROSS THE EAST
THROUGH MUCH OF WEEK-2. AT LEAST A COUPLE OF SHORTWAVE IMPULSES ARE EXPECTED TO
TRAVERSE THE CENTRAL AND EASTERN CONUS THE FIRST HALF OF WEEK-2, FAVORING AN
ACTIVE WEATHER PATTERN ACROSS THE EAST. THE INTERACTION BETWEEN THE SOUTHERN
AND NORTHERN STREAMS WILL ULTIMATELY DETERMINE THE PLACEMENT OF WINTRY WEATHER
AND THE INTENSITY OF PRECIPITATION, BUT PROBABILISTIC OUTPUT FROM THE ECMWF,
GEFS, AND CANADIAN ENSEMBLES ALONG WITH AN ENHANCED SIGNAL ON THE GEFS
PROBABILISTIC EXTREMES TOOL (PET) SUPPORT A SLIGHT RISK OF HEAVY SNOW ACROSS
PORTIONS OF THE GREAT LAKES AND INTERIOR NORTHEAST, EXTENDING SOUTHWARD ALONG
THE ALLEGHENY FRONT, DEC 10-11, WITH HEAVY SNOW EITHER DIRECTLY ASSOCIATED WITH
THE INDIVIDUAL SHORTWAVE IMPULSES, OR LAKE EFFECT SNOW IN THEIR WAKE.
THE 0Z ECWMF, GEFS, AND CANADIAN ENSEMBLES DEPICT AN AMPLIFIED RIDGE-TROUGH
DIPOLE FROM WEST OF ALASKA THROUGH THE NORTHEAST NORTH PACIFIC EARLY WEEK-2.
THIS SET-UP FAVORS SURFACE HIGH PRESSURE AND EXCEPTIONALLY COLD AIR ACROSS MUCH
OF MAINLAND ALASKA, ALONG WITH SURFACE LOW PRESSURE FARTHER SOUTH THAT MAY
BRING HIGH WINDS ALONG THE SOUTHERN TIER OF THE STATE. THERE ARE SIGNIFICANT
DIFFERENCES IN MINIMUM TEMPERATURE FORECASTS AMONG THE TOOLS, BUT ECENS AND
CNENS MEANS DEPICT TEMPERATURE REACHING -30 TO -45 DEG. F OVER PARTS OF CENTRAL
AND EASTERN ALASKA. THE ECMWF AND CANADIAN DYNAMICAL MODELS ARE EVEN MORE
EXTREME, HIGHLIGHTING WIND CHILLS DROPPING BELOW -30 DEG. F OVER MOST OF INLAND
ALASKA, REACHING AS LOW AS -55 DEG. F AT TIMES OVER PARTS OF THE CENTRAL AND
EASTERN MAINLAND. AS A RESULT, A SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES
IS POSTED FOR ALMOST ALL OF CENTRAL AND SOUTHERN ALASKA. TEMPERATURES SHOULD
MODERATE AFTER THE MIDDLE OF THE PERIOD, BUT SURFACE LOW PRESSURE SYSTEMS ARE
EXPECTED TO CONTINUE AFFECTING SOUTHERN PARTS OF THE STATE PERIODICALLY
THROUGHOUT WEEK-2. DYNAMICAL MODELS INDICATE WIND GUSTS MAY BRIEFLY PEAK AT OR
ABOVE HURRICANE FORCE (74 MPH) OVER WATER, NEAR THE COAST, AND IN ISLAND AND
INLET GAPS. FOR THIS REASON, A SLIGHT RISK OF HIGH WINDS IS POSTED FOR ALL OF
WEEK-2 ALONG THE ENTIRE SOUTHERN TIER OF ALASKA FROM THE CENTRAL ALEUTIANS
THROUGH MOST OF SOUTHEAST ALASKA.
THE MID-LEVEL LOW PRESSURE OVER THE NORTH PACIFIC AND AMPLIFYING MID-LEVEL HIGH
PRESSURE FARTHER SOUTH NEAR THE WESTERN CONUS SHOULD BRING STRONG PACIFIC FLOW
ACROSS THE NORTHWESTERN QUARTER OF THE CONUS, WHICH IS EXPECTED TO RESULT IN
HEAVY PRECIPITATION (INCLUDING HEAVY HIGH-ELEVATION SNOWS) AND HIGH WINDS EARLY
WEEK-2. THE PETS DERIVED FROM THE ENSEMBLE MEANS ARE NOT QUITE AS ROBUST WITH
ODDS FOR HEAVY PRECIPITATION AS THEY WERE YESTERDAY, AND ARE A BIT FARTHER
NORTH. ENSEMBLE MEAN AND DYNAMICAL MODEL OUTPUT ALSO SHOW HEAVY PRECIPITATION A
LITTLE FARTHER NORTH, BUT SOME OF THE DYNAMICAL MODELS SHOW SIMILAR OR SLIGHTLY
HIGHER TOTALS COMPARED TO YESTERDAY. THEREFORE, A MODERATE RISK OF HEAVY
PRECIPITATION IS POSTED FOR THE FIRST TWO DAYS OF WEEK-2 FOR THE WESTERN
WASHINGTON AND NORTHWESTERN OREGON, WITH A SLIGHT RISK OF HEAVY PRECIPITATION
THROUGH THE FIRST 3 DAYS OF THE PERIOD OVER A LARGER PART OF THE NORTHWESTERN
CONUS EXTENDING INTO THE NORTHERN ROCKIES AND ADJACENT AREAS. PETS BASED ON THE
GEFS AND ECENS SHOW CHANCES FOR PRECIPITATION TOTALS ABOVE THE 85TH PERCENTILE
IN THE 20 TO 50 PERCENT RANGE IN THE WETTEST AREAS, WITH 20 TO 30 PERCENT ODDS
FOR AMOUNTS EXCEEDING 2 INCHES IN WESTERN WASHINGTON AND THE NORTHERN
WASHINGTON CASCADES. IN THE HIGHER ELEVATIONS, MOST OR ALL OF THIS
PRECIPITATION SHOULD FALL AS SNOW, SO A MODERATE RISK OF HEAVY SNOW IS POSTED
FOR THE NORTHERN WASHINGTON CASCADES, WITH SLIGHT RISKS FOR HEAVY SNOW
EXTENDING THROUGH MOST OF THE REST OF THE CASCADES, AND ALSO THE HIGHER
ELEVATIONS OF THE NORTHERN ROCKIES. MULTIPLE FEET OF SNOW ARE FORECAST BY THE
DYNAMICAL GUIDANCE IN THE NORTHERN WASHINGTON CASCADES. THE HIGH WIND GUIDANCE
FROM THE PETS REMAINS AS ROBUST AS YESTERDAY, PERHAPS A LITTLE MORESO IN SOME
LOCATIONS. THEY ALSO BRING THE ENHANCED HIGH WIND RISKS A LITTLE FARTHER SOUTH
THAN INDICATED YESTERDAY. AS A RESULT, A MODERATE RISK OF HIGH WINDS FOR THE
FIRST 2 DAYS OF WEEK-2 COVERS A LARGE PART OF THE NORTHWESTERN QUARTER OF THE
CONUS, WITH A SLIGHT RISK EXTENDING SOMEWHAT FARTHER TO THE SOUTH AND EAST
THROUGH THE FIRST 3 DAYS OF THE PERIOD. APPROACHING THE MIDDLE OF WEEK-2,
ENSEMBLE MEANS AND DYNAMICAL MODEL OUTPUT SHOW MID-LEVEL FEATURES WEAKENING,
ENDING THE PRECIPITATION, SNOW, AND WIND RISKS.
FORECASTER: RICH TINKER
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