801
FXUS21 KWNC 022048
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 02 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
THROUGHOUT THE WEEK-2 PERIOD, AS WELL AS STRONG MID-LEVEL HIGH PRESSURE OVER
THE WESTERN CONUS AND GREENLAND, SETTING UP A BLOCKING PATTERN THAT IS FAVORED
TO FUNNEL ARCTIC AIR INTO THE LOWER 48 EAST OF THE ROCKIES WITH HIGH CHANCES
FOR HAZARDOUS COLD CONDITIONS, AS WELL AS THE POTENTIAL FOR HEAVY SNOW FOR THE
HIGH PLAINS AND GREAT LAKES REGIONS AS WELL AS PORTIONS OF THE SOUTHERN PLAINS
ACROSS TO THE MID-ATLANTIC REGION. STRONG SURFACE LOW PRESSURE OVER THE BERING
SEA IS FAVORED TO PRODUCE HIGH WINDS AND HEAVY PRECIPITATION FOR THE SOUTHERN
COAST OF ALASKA.
HAZARDS
HIGH RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR MUCH OF THE SOUTHEASTERN U.S.
AND PORTIONS OF THE LOWER MISSISSIPPI AND TENNESSEE VALLEYS, FRI-SAT, JAN 10-11.
MODERATE RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR THE SOUTHEASTERN U.S.,
TENNESSEE AND OHIO VALLEYS, AND THE APPALACHIANS, AS WELL AS MUCH OF THE
MID-ATLANTIC, AND LOWER AND MIDDLE MISSISSIPPI VALLEY, AND PORTIONS OF THE
GREAT LAKES, AND CENTRAL AND SOUTHERN PLAINS, FRI-SUN, JAN 10-12.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR MUCH OF THE CENTRAL AND
EASTERN CONUS WITH THE EXCEPTION OF THE WESTERN GREAT PLAINS AND THE NORTHEAST
U.S., FRI-THU, JAN 10-16.
SLIGHT RISK OF HEAVY SNOW FOR PORTIONS OF THE GREAT LAKES FAVORABLE FOR
LAKE-EFFECT SNOW, AND ALONG THE ALLEGHENY FRONT, FRI-TUE, JAN 10-14.
SLIGHT RISK OF HEAVY SNOW FOR MUCH OF THE TENNESSEE VALLEY AS WELL AS PORTIONS
OF THE MID-ATLANTIC, SOUTHEASTERN U.S., AND LOWER AND MIDDLE MISSISSIPPI
VALLEY, FRI, JAN 10.
SLIGHT RISK OF HEAVY SNOW FOR PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES, AND
NORTHERN AND CENTRAL PLAINS, FRI-TUE, JAN 10-14.
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF THE NORTHERN AND CENTRAL PLAINS,
FRI-TUE, JAN 10-14.
MODERATE RISK OF HEAVY SNOW FOR THE WESTERN ALASKA RANGE, AND HIGHER ELEVATIONS
OF MOUNTAINS ALONG THE SOUTHERN COAST AND KODIAK ISLAND, FRI-TUE, JAN 10-14.
SLIGHT RISK OF HEAVY SNOW FOR LOWER ELEVATIONS ADJACENT TO RANGES LISTED ABOVE,
FRI-TUE, JAN 10-14.
SLIGHT RISK OF HEAVY PRECIPITATION FOR MUCH OF THE SOUTHERN AND SOUTHEASTERN
COAST OF ALASKA, FRI-TUE, JAN 10-14.
SLIGHT RISK OF HIGH WINDS FOR THE SOUTHERN AND SOUTHEASTERN COAST OF ALASKA,
FRI-TUE, JAN 10-14.
DETAILED SUMMARY
FOR SUNDAY JANUARY 05 - THURSDAY JANUARY 09:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR FRIDAY JANUARY 10 - THURSDAY JANUARY 16: MODEL ENSEMBLES CONTINUE TO BE IN
VERY GOOD AGREEMENT REGARDING DEPICTION OF A DEEP TROUGH OVER THE EASTERN CONUS
DURING THE WEEK-2 PERIOD, AS WELL AS AMPLIFIED RIDGING OVER GREENLAND AND THE
WEST COAST, RESULTING IN A LONG FETCH OF NORTHERLY WINDS FROM THE CANADIAN
ARCTIC THROUGH MUCH OF THE CENTRAL AND EASTERN CONUS LEADING TO HIGH POTENTIAL
FOR HAZARDOUS COLD ACROSS MUCH OF THE LOWER 48 EAST OF THE ROCKIES. TODAY’S
MODEL GUIDANCE FAVORS A WEAKENING OF THE BLOCKING RIDGES LATER IN WEEK-2 AND A
GRADUAL MODERATION OF THE INTRUDING ARCTIC AIRMASS. NONETHELESS, THIS IS LIKELY
TO BE A VERY IMPACTFUL SURGE OF ARCTIC AIR NEAR THE PEAK OF WINTER FOR MUCH OF
THE CENTRAL AND EASTERN CONUS. THE ECMWF AND GEFS PROBABILISTIC EXTREMES TOOLS
(PETS) BOTH INDICATE AT LEAST A 20% CHANCE OF LOW TEMPERATURES FALLING BELOW
THE 15TH PERCENTILE THROUGHOUT WEEK-2 FOR MUCH OF THE CONUS EAST OF 100W EXCEPT
FOR THE NORTHERN PLAINS ACROSS TO THE NORTHEAST U.S. THERE IS ALSO WIDESPREAD
COVERAGE OF GREATER THAN 40% PROBABILITIES FOR JAN 10-12 OVER NEARLY THE SAME
AREAS AS LISTED ABOVE (WITH THE EXCEPTION OF THE UPPER MISSISSIPPI VALLEY AND
GREAT LAKES). ADDITIONALLY, A HIGH RISK (AT LEAST A 60% CHANCE) OF MUCH
BELOW-NORMAL TEMPERATURES IS POSTED FOR MUCH OF THE SOUTHEASTERN U.S. AS WELL
AS PORTIONS OF THE SOUTHERN APPALACHIANS, AND TENNESSEE AND LOWER MISSISSIPPI
VALLEYS FOR JAN 10-11, WHERE THE PETS SHOW THE STRONGEST SIGNAL FOR REACHING
HAZARDOUS TEMPERATURES IN PERCENTILE SPACE AND WHERE WELL-BELOW FREEZING
TEMPERATURES ARE VERY LIKELY. 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
THROUGHOUT 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 10-14, DURING WHICH THE PETS ARE IN STRONGEST AGREEMENT.
IN ADDITION TO THE ANTICIPATED BITTER COLD, NORTHERLY WINDS FROM CANADA AND
SURFACE LOW PRESSURE OVER THE CANADIAN MARITIMES FAVORS INCREASED CHANCES FOR
HEAVY SNOW FOR PORTIONS OF THE CENTRAL AND EASTERN CONUS THROUGH THE MIDDLE OF
WEEK-2. THE INCREASED RISK FOR HEAVY SNOW EVEN EXTENDS INTO THE SOUTHERN TIER
EARLY IN THE FORECAST PERIOD AS A SURFACE LOW MAY TRACK AS FAR NORTH AS THE
SOUTHERN PLAINS TO THE MID-ATLANTIC, TAPPING INTO MOISTURE OFF THE GULF OF
MEXICO. ECMWF RAW ENSEMBLE SNOWFALL TOTALS HAVE CONSISTENTLY INDICATED MEAN
ACCUMULATIONS NEAR 2”, AND SEVERAL RECENT DETERMINISTIC GFS RUNS DEPICT HEAVY
SNOWFALL ASSOCIATED WITH THE TRACKING SURFACE LOW. WHILE SIGNIFICANT
ACCUMULATIONS ARE NOT EXPECTED, THESE REGIONS ARE OFTEN ILL-EQUIPPED TO HANDLE
SNOWY CONDITIONS, RESULTING IN POTENTIALLY HIGHER IMPACTS WITH LOWER SNOWFALL
TOTALS. IT SHOULD BE NOTED THAT THIS SOUTHERN AREA HIGHLIGHTED FOR THE RISK OF
HEAVY SNOW COULD ALSO EXPERIENCE A VARIETY OF MIXED PRECIPITATION TYPES INSTEAD
OF ALL SNOW. GIVEN RECENT MODEL SPREAD REGARDING TIMING, THE VALID PERIOD FOR
TODAY’S SLIGHT RISK OF HEAVY SNOW COVERING THE SOUTHERN TIER IS NOT BEING
EXTENDED AND IS VALID JAN 10, AND THIS UNFOLDING SITUATION WILL CONTINUE TO BE
MONITORED.
GREATER SNOW ACCUMULATIONS ARE FAVORED FURTHER NORTH 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 AND OVER THE APPALACHIANS FROM
JAN 10-14, AFTER WHICH SNOWFALL TOTALS TAPER OFF BELOW HAZARDOUS THRESHOLDS.
THE MODERATE RISKS OF HEAVY SNOW POSTED YESTERDAY HAVE BEEN REMOVED DUE TO A
COMBINATION OF SOME OF THE ANTICIPATED HEAVY SNOW SHIFTING INTO THE WEEK-1
PERIOD, AS WELL AS LOWER SNOWFALL TOTALS INDICATED BY ECMWF ENSEMBLES RELATIVE
TO PREVIOUS DAYS. A SLIGHT RISK OF HEAVY SNOW HAS ALSO BEEN POSTED FOR PORTIONS
OF THE CENTRAL AND NORTHERN ROCKIES, AND CENTRAL AND NORTHERN PLAINS FOR JAN
10-14, WITH PASSING SHORTWAVE TROUGHS WITHIN NORTHWEST FLOW ALOFT FAVORED TO
PRODUCE SEVERAL ROUNDS OF SNOWFALL. WHILE LARGE ACCUMULATIONS ARE NOT
ANTICIPATED OVER THE PLAINS, WHEN COMBINED WITH THE RISK OF HIGH WINDS
HIGHLIGHTED ABOVE THE POTENTIAL FOR BLIZZARD CONDITIONS WARRANTS INCLUDING THIS
HAZARD 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 10-14 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, KODIAK ISLAND, THE
KENAI PENINSULA, AND COASTAL RANGES EASTWARD TO YAKUTAT FOR JAN 10-14, WHILE A
SLIGHT RISK OF HEAVY SNOW IS POSTED FOR LOWER ELEVATIONS NEAR THE RANGES LISTED
ABOVE, ALSO FOR JAN 10-14.
FORECASTER: DANNY BARANDIARAN
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