930
FXUS21 KWNC 031955
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 03 2025
SYNOPSIS: MULTIPLE MODEL ENSEMBLES DEPICT DEEP MID-LEVEL LOW PRESSURE OVER THE
EASTERN CONTIGUOUS U.S. (CONUS) DEVELOPING EARLY IN WEEK-1 AND PERSISTING INTO
WEEK-2. WITH STRONG MID-LEVEL HIGH PRESSURE OVER THE WESTERN CONUS AND
GREENLAND, THIS BLOCKING PATTERN IS FAVORED TO FUNNEL ARCTIC AIR INTO THE
LOWER 48 EAST OF THE ROCKIES WITH LINGERING CHANCES FOR HAZARDOUS COLD
CONDITIONS EARLY IN WEEK-2 AS WELL AS THE POTENTIAL FOR HEAVY SNOW FOR PORTIONS
OF THE HIGH PLAINS, GREAT LAKES, AND THE ROCKIES DURING THE PERIOD. STRONG
SURFACE LOW PRESSURE OVER THE BERING SEA IS FAVORED TO PRODUCE HIGH WINDS AND
HEAVY PRECIPITATION FOR THE SOUTHERN COAST OF ALASKA.
HAZARDS
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR THE SOUTHEASTERN U.S.,
TENNESSEE VALLEY, AND THE SOUTHERN APPALACHIANS, AS WELL AS PORTIONS OF THE
MID-ATLANTIC, CENTRAL APPALACHIANS, AND THE OHIO AND LOWER MISSISSIPPI VALLEYS,
SAT, JAN 11.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR THE SOUTHEASTERN U.S.
TENNESSEE AND OHIO VALLEYS, AS WELL AS PORTIONS OF THE LOWER AND MIDDLE
MISSISSIPPI VALLEY, CENTRAL APPALACHIANS, AND MID-ATLANTIC, SAT-SUN, JAN 11-12.
SLIGHT RISK OF HEAVY SNOW FOR AREAS NEAR LAKES ERIE AND ONTARIO FAVORABLE FOR
LAKE-EFFECT SNOW, MON-WED, JAN 13-15.
SLIGHT RISK OF HEAVY SNOW FOR MUCH OF THE ROCKIES AND NORTHERN PLAINS, AS WELL
AS THE NORTHERN AND CENTRAL PLAINS, SAT-MON, JAN 11-13.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE NORTHERN AND CENTRAL PLAINS,
SAT-WED, JAN 11-15.
MODERATE RISK OF HEAVY SNOW FOR THE WESTERN ALASKA RANGE AND HIGHER ELEVATIONS
OF MOUNTAINS ALONG THE SOUTHERN COAST FROM THE KENAI PENINSULA TO YAKUTAT,
SAT-WED, JAN 11-15.
SLIGHT RISK OF HEAVY SNOW FOR LOWER ELEVATIONS ADJACENT TO RANGES LISTED ABOVE
AS WELL AS THE REMAINDER OF THE ALASKA RANGE AND THE COPPER RIVER BASIN,
SAT-WED, JAN 11-15.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE SOUTHERN AND SOUTHEASTERN
COAST OF ALASKA, SAT-WED, JAN 11-15.
SLIGHT RISK OF HIGH WINDS FOR THE SOUTHERN AND SOUTHEASTERN COAST OF ALASKA,
SAT-WED, JAN 11-15.
DETAILED SUMMARY
FOR MONDAY JANUARY 06 - FRIDAY JANUARY 10:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY JANUARY 11 - FRIDAY JANUARY 17: MODEL ENSEMBLE SOLUTIONS ARE
BEGINNING TO DIVERGE WITH RESPECT TO EARLIER DEPICTIONS OF THE DEEP TROUGH OVER
THE EAST COAST AND PARTICULARLY THE ORIENTATION OF THE BLOCKING RIDGE OVER THE
WEST COAST. WHILE A STRONG ARCTIC AIR OUTBREAK WITH VERY COLD TEMPERATURES IS
STILL EXPECTED, TODAY’S MODEL GUIDANCE SUGGESTS THAT HIGHEST RISK OF EXTREME
COLD IS NOW IN WEEK-1 WITH ONLY A LINGERING RISK OF HAZARDOUS COLD EARLY IN
WEEK-2, MOSTLY FOR THE SOUTHEASTERN CONUS. THE ECMWF AND GEFS PROBABILISTIC
EXTREMES TOOLS (PETS) BOTH INDICATE AT LEAST A 20% CHANCE OF LOW TEMPERATURES
FALLING BELOW THE 15TH PERCENTILE EARLY IN WEEK-2 FOR MUCH OF THE EASTERN CONUS
SOUTH OF THE GREAT LAKES AS WELL AS PORTIONS OF THE LOWER AND MIDDLE
MISSISSIPPI VALLEY FOR JAN 11-12 WHERE A SLIGHT RISK OF MUCH BELOW NORMAL
TEMPERATURES IS ISSUED. THE PETS ALSO INDICATE GREATER THAN 40% PROBABILITIES
OVER NEARLY THE SAME AREAS AS LISTED ABOVE (WITH THE EXCEPTION OF AREAS WEST OF
THE MISSISSIPPI RIVER AND NORTH OF THE OHIO RIVER) SUPPORTIVE OF THE
CONTINUATION OF A CORRESPONDING MODERATE RISK AREA FOR JAN 11. THE POTENTIAL
FOR A HARD FREEZE EXTENDS WELL INTO THE FLORIDA PENINSULA, WHICH COULD
NEGATIVELY IMPACT CITRUS PRODUCTION IN THE STATE. IN ADDITION TO THE VERY COLD
TEMPERATURES MULTIPLE MODELS SHOW A BROAD AREA WITH POSSIBLY TIGHT PRESSURE
GRADIENT OVER MUCH OF THE EASTERN CONUS EARLY IN THE WEEK, WHICH COULD RESULT
IN WIDESPREAD BREEZY CONDITIONS AND VERY LOW WIND CHILLS. TODAY’S ECMWF AND
CMCE PETS INDICATE THAT WINDS SPEEDS HAVE AT LEAST A 20% CHANCE OF EXCEEDING
THE 85TH PERCENTILE OVER PORTIONS OF THE NORTHERN AND CENTRAL PLAINS, THEREFORE
A SLIGHT RISK FOR HIGH WINDS IS POSTED FOR JAN 11-15, DURING WHICH THE PETS ARE
IN STRONGEST AGREEMENT.
IN ADDITION TO THE ANTICIPATED BITTER COLD, EMBEDDED SHORTWAVES WITHIN
NORTHERWESTERLY FLOW ALOFT FAVORS INCREASED CHANCES FOR HEAVY SNOW FOR
PORTIONS OF THE GREAT PLAINS AND ROCKIES EARLY IN WEEK-2. POTENTIALLY IMPACTFUL
SNOW ACCUMULATIONS ARE ALSO FAVORED FURTHER EAST WITH FAVORABLE LAKE-EFFECT
SNOW CONDITIONS DOWNWIND OF LAKES ERIE AND ONTARIO. THE GEFS PET INDICATES A
20% CHANCE OF 3-DAY ACCUMULATED SNOW WATER EQUIVALENT (SWE) EXCEEDING THE 85TH
PERCENTILE, AND MODEL ENSEMBLE TOTALS FOR SNOWFALL FROM THE ECMWF CONTINUE TO
DEPICT ENHANCED SNOWFALL NEAR THE GREAT LAKES FROM JAN 13-15 AFTER A BRIEF LULL
AT THE OUTSET OF WEEK-2. A SLIGHT RISK OF HEAVY SNOW HAS ALSO BEEN POSTED FOR
MUCH OF THE ROCKIES, AS WELL AS PORTIONS OF THE CENTRAL AND NORTHERN PLAINS FOR
JAN 11-15, WHERE PASSING SHORTWAVES ARE FAVORED TO PRODUCE SEVERAL ROUNDS OF
SNOWFALL. WHILE LARGE ACCUMULATIONS ARE NOT ANTICIPATED OVER THE PLAINS, WHEN
COMBINED WITH THE INCREASED RISK OF HIGH WINDS HIGHLIGHTED ABOVE, THERE IS THE
POTENTIAL FOR BLIZZARD CONDITIONS OVER THE PLAINS IN TODAY’S OUTLOOK.
AMPLIFIED RIDGING OVER THE WEST COAST AND STRONG SURFACE LOW PRESSURE OVER THE
BERING SEA THROUGHOUT WEEK-2 FAVORS STRONG MOIST ONSHORE FLOW INTO THE SOUTHERN
COAST OF ALASKA. THE ECMWF AND GEFS PETS BOTH INDICATE A 20% CHANCE OF 3-DAY
RAINFALL TO EXCEED THE 85TH PERCENTILE AND 2-3 INCHES FOR MUCH OF THE ALASKAN
COAST FROM THE KENAI PENINSULA EAST ALONG THE COAST AND DOWN THROUGH THE
PANHANDLE. MODEL OUTPUT ALSO INDICATES THE POTENTIAL FOR WINDS EXCEEDING 40MPH
ALONG THE SAME STRETCH OF ALASKAN COAST, ALTHOUGH THE SIGNAL FOR BOTH HEAVY
PRECIPITATION AND HIGH WINDS TAILS OFF TOWARDS THE END OF THE WEEK-2 PERIOD.
THEREFORE, SLIGHT RISKS OF HEAVY PRECIPITATION AND HIGH WINDS ARE POSTED FOR
JAN 11-15 FOR THE AREAS HIGHLIGHTED ABOVE. ADDITIONALLY, ECMWF ENSEMBLE SNOW
ACCUMULATIONS HAVE INCREASED NOTICEABLY OVER THE PAST FEW DAYS ALONG THE
SOUTHERN COAST. WHILE ABOVE-NORMAL TEMPERATURES ARE STRONGLY FAVORED ALONG THE
COAST, HIGHER ELEVATIONS COULD SEE SUBSTANTIAL SNOWFALL ACCUMULATIONS AS A
RESULT OF THE PERSISTENT MOISTURE INFLUX. A MODERATE RISK OF HEAVY SNOW IS
POSTED FOR HIGHER ELEVATIONS OF THE WESTERN ALASKA RANGE, THE KENAI PENINSULA,
AND COASTAL RANGES EASTWARD TO YAKUTAT FOR JAN 11-15, WHILE A SLIGHT RISK OF
HEAVY SNOW IS POSTED FOR LOWER ELEVATIONS NEAR THE RANGES LISTED ABOVE AS WELL
AS THE REMAINDER OF THE ALASKA RANGE AND THE COPPER RIVER BASIN, ALSO FOR JAN
JAN 11-15.
FORECASTER: DANNY BARANDIARAN
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page