633
FXUS21 KWNC 311941
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 31 2025
SYNOPSIS: AN AMPLIFIED MID-LEVEL HEIGHT PATTERN IS FORECAST TO DEVELOP DURING
THE WEEK-2 PERIOD, WITH MID-LEVEL LOW PRESSURE PREDICTED OVER THE WEST, WITH
AREAS OF MID-LEVEL HIGH PRESSURE ACROSS THE EASTERN PACIFIC AND ALASKA, AND
NEAR THE EAST COAST. THIS FAVORS BELOW-NORMAL TEMPERATURES TO PERSIST ACROSS
PORTIONS OF THE NORTHWESTERN AND NORTH-CENTRAL CONTIGUOUS U.S. (CONUS)
THROUGHOUT THE PERIOD. A SERIES OF SURFACE LOWS ARE PREDICTED TO TRACK ACROSS
THE EAST-CENTRAL CONUS. MODELS HAVE TRENDED COLDER ACROSS THE NORTHERN TIER
COMPARED TO YESTERDAY, AND THERE ARE INCREASING CHANCES FOR HEAVY SNOW OR
WINTRY WEATHER ACROSS PORTIONS OF THE NORTHEAST AND NEW ENGLAND, AND HEAVY RAIN
ACROSS REMAINING PORTIONS OF THE EAST AND SOUTHEAST DEPENDENT ON THE EXACT
TRACK OF INDIVIDUAL SURFACE LOWS.
HAZARDS
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE PACIFIC
NORTHWEST, SAT-MON, FEB 8-10.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE
NORTHWESTERN CONUS AND EXTENDING INTO THE NORTHERN ROCKIES AND PLAINS, SAT-FRI,
FEB 8-14.
MODERATE RISK OF HEAVY SNOW ACROSS PORTIONS OF NORTHERN NEW ENGLAND, SAT-MON,
FEB 8-10.
SLIGHT RISK OF HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN PLAINS, UPPER
MISSISSIPPI VALLEY, GREAT LAKES, AND NORTHEAST, SAT-FRI, FEB 8-14.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS MUCH OF THE EASTERN CONUS, SAT-FRI,
FEB 8-14.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF SOUTHERN CALIFORNIA, SAT-SUN, FEB
8-9.
DETAILED SUMMARY
FOR MONDAY FEBRUARY 03 - FRIDAY FEBRUARY 07:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR SATURDAY FEBRUARY 08 - FRIDAY FEBRUARY 14: TROUGHING IS FORECAST ACROSS THE
NORTHWESTERN CONUS DURING WEEK-2 FAVORING ENHANCED CHANCES OF BELOW-NORMAL
TEMPERATURES ALONG THE WEST COAST AND INTO PARTS OF THE NORTH-CENTRAL CONUS.
THE MOST ANOMALOUS COLD IS PREDICTED TO BE ACROSS THE PACIFIC NORTHWEST, WHERE
THE ECENS AND GEFS PROBABILISTIC EXTREMES TOOLS (PETS) DEPICT PROBABILITIES OF
AT LEAST 40 PERCENT FOR MINIMUM TEMPERATURES FALLING BELOW THE 15TH
CLIMATOLOGICAL PERCENTILE. THE UNCALIBRATED 0Z GEFS AND ECENS AS WELL AS THE
NATIONAL BLEND OF MODELS INDICATE MINIMUM TEMPERATURES IN THE MID- TO UPPER 20S
DEG F. THIS SUPPORTS THE MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES
THROUGH DAY-10 (FEB 10) ACROSS THE PACIFIC NORTHWEST. THE ECENS, GEFS, AND CMCE
DEPICT PERSISTENT TROUGHING OVER THE WEST DURING THE PERIOD. THEREFORE,
ANOMALOUSLY COLD TEMPERATURES ARE FORECAST TO CONTINUE THROUGHOUT WEEK-2
SUPPORTING THE SLIGHT RISK FOR THE ENTIRE PERIOD. THE SLIGHT RISK AREA INCLUDES
PORTIONS OF THE NORTHERN ROCKIES, NORTHERN PLAINS, AND UPPER MISSISSIPPI VALLEY
WHERE SUBZERO TEMPERATURES ARE POSSIBLE. WHILE THESE TEMPERATURES ARE
CONSIDERABLY COLDER COMPARED TO THE COASTAL PACIFIC NORTHWEST, IT IS LESS
CERTAIN IF APPARENT TEMPERATURES WILL REACH THE VERY COLD HAZARDOUS CRITERIA
ACROSS THE NORTH-CENTRAL CONUS, JUSTIFYING ONLY A SLIGHT RISK. ENHANCED ONSHORE
FLOW IS POSSIBLE ALONG THE WEST COAST, ESPECIALLY DURING THE SECOND HALF OF THE
PERIOD. THIS MAY LEAD TO EPISODES OF HEAVY PRECIPITATION, WITH SNOW OR WINTRY
WEATHER POSSIBLE ACROSS LOW ELEVATION AREAS GIVEN THE COLD AIR MASS IN PLACE.
HOWEVER, 24-HOUR TOTALS APPEAR MARGINAL AND THEREFORE, NO RELATED PRECIPITATION
OR SNOW HAZARDS ARE INDICATED AT THIS TIME.
THE TROUGHING OVER THE WESTERN CONUS AND RIDGING ALONG THE EASTERN SEABOARD
FAVORS AN ENHANCED BAROCLINIC ZONE OVER THE EAST-CENTRAL CONUS, AND MULTIPLE
AREAS OF SURFACE LOW PRESSURE TO TRACK ACROSS THE REGION. THERE IS IMPROVING
MODEL CONSENSUS REGARDING A SURFACE LOW MOVING THROUGH THE EAST PRIOR TO THE
START OF WEEK-2, FOLLOWED BY SOME COLDER AIR AND ANOTHER WAVE OF LOW PRESSURE
AROUND DAY-9 (FEB 9). MID-LEVEL HEIGHT FALLS BEHIND THE INITIAL WAVE WOULD
SUPPORT A PERIOD OF RELATIVELY COLDER TEMPERATURES, AND ENSEMBLES INDICATE
ENHANCED CHANCES FOR A PERIOD OF SNOW OR SNOW CHANGING TO RAIN WITH THE SECOND
WAVE, PARTICULARLY ACROSS NEW ENGLAND. THE UNCALIBRATED 0Z ECENS DEPICTS
PROBABILITIES OF 40-50 PERCENT FOR SNOWFALL EXCEEDING 4-INCHES ACROSS NORTHERN
NEW ENGLAND ON DAYS 8-10 (FEB 8-10), WITH ADDED SUPPORT FROM THE 0Z AND 6Z GEFS
INDICATING ELEVATED CHANCES 24-HOUR SNOWFALL EXCEEDS 3-INCHES OVER SOME
LOCATIONS. ADDITIONALLY, THE GEFS SNOW WATER EQUIVALENT (SWE) PET DEPICTS AREAS
OF UPSTATE NEW YORK, VERMONT, NEW HAMPSHIRE, AND MAINE WITH A 30-40 PERCENT
CHANCE 3-DAY SWE EXCEEDS 0.5-INCHES. WHILE THIS IS MORE LIKELY TO BE A
LOW-IMPACT EVENT, THE FORECAST TOOLS SUPPORT A MODERATE RISK FOR HEAVY SNOW
ACROSS NORTHERN NEW ENGLAND FEB 8-10, AND A SLIGHT RISK OF HEAVY SNOW EXTENDS
FURTHER TO THE SOUTH AND BACK THROUGH THE MIDWEST FOR ALL OF WEEK-2. A BROAD
SLIGHT RISK OF HEAVY PRECIPITATION IS POSTED ACROSS MUCH OF THE EASTERN CONUS
FOR ALL OF WEEK-2 ALONG THE SOUTHERN AND EASTERN TRACKS OF SURFACE LOW PRESSURE.
OFFSHORE FLOW IS FAVORED TO INCREASE ACROSS SOUTHERN CALIFORNIA EARLY IN THE
PERIOD AS SURFACE HIGH PRESSURE MOVES BY TO THE NORTH. WHILE SIGNALS FOR
HAZARDOUS WINDS ARE MODEST AT BEST IN THE GUIDANCE, THERE IS HIGH SENSITIVITY
IN THE REGION DUE TO RECENT AND ONGOING WILDFIRES. THEREFORE, A SLIGHT RISK FOR
HIGH WINDS IS HIGHLIGHTED FEB 8-9.
RIDGING IS FORECAST OVER ALASKA DURING WEEK-2 FAVORING RELATIVELY WARMER
TEMPERATURES OVER MUCH OF THE MAINLAND AND ALEUTIANS COMPARED TO WEEK-1.
BELOW-NORMAL TEMPERATURES REMAIN FORECAST ACROSS SOUTHEAST ALASKA, BUT HAZARDS
THRESHOLDS ARE UNLIKELY TO BE REACHED. BELOW-NORMAL PRECIPITATION IS ALSO
PREDICTED OVER MUCH OF SOUTHERN ALASKA, WITH RIDGING PUSHING HIGHER CHANCES OF
PRECIPITATION FURTHER TO THE NORTH ACROSS THE WESTERN AND NORTHERN MAINLAND.
FORECASTER: THOMAS COLLOW
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