125
FXUS21 KWNC 271931
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 27 2025
SYNOPSIS: MID-LEVEL LOW PRESSURE FORECAST DURING WEEK-2 FAVORS COLDER THAN
NORMAL TEMPERATURES OVER MUCH OF THE NORTHWESTERN CONTIGUOUS U.S. (CONUS), AND
EXTENDING INTO THE NORTHERN ROCKIES AND PLAINS. ADDITIONALLY, ENHANCED ONSHORE
FLOW IS LIKELY TO RESULT IN ROUNDS OF HEAVY PRECIPITATION ACROSS THE WEST
COAST. HEAVY SNOW IS MOST LIKELY ACROSS THE HIGHER ELEVATIONS OF THE CASCADES,
KLAMATH, AND SIERRA NEVADA MOUNTAINS. HOWEVER, SNOW OR WINTRY WEATHER CANNOT BE
RULED OUT OVER LOWER ELEVATION AREAS INCLUDING THE CITIES OF PORTLAND, OR AND
SEATTLE, WA DUE TO THE ANOMALOUSLY COLD AIR MASS PREDICTED TO BE IN PLACE.
TOWARD THE MIDDLE OF THE PERIOD, A SURFACE LOW IS PREDICTED TO EJECT EASTWARD
BRINGING INCREASED CHANCES OF HEAVY SNOW ACROSS THE NORTHERN TIER, WITH AN
ENHANCED RISK OF HEAVY RAIN OVER PARTS OF THE SOUTH-CENTRAL AND SOUTHEASTERN
CONUS. MID-LEVEL HIGH PRESSURE FAVORS INCREASING CHANCES FOR NEAR TO ABOVE
NORMAL TEMPERATURES ACROSS THE SOUTHERN AND EASTERN CONUS DURING THE PERIOD.
HAZARDS
MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE PACIFIC
NORTHWEST, TUE-FRI, FEB 4-7.
SLIGHT RISK OF MUCH BELOW NORMAL TEMPERATURES ACROSS PORTIONS OF THE
NORTHWESTERN CONUS AND EXTENDING INTO THE NORTHERN ROCKIES AND PLAINS, TUE-MON,
FEB 4-10.
SLIGHT RISK OF HEAVY SNOW ACROSS PORTIONS OF THE CASCADES, KLAMATH, AND SIERRA
NEVADA MOUNTAINS, AND ALSO INCLUDING LOWER ELEVATIONS OF WASHINGTON AND OREGON,
TUE-MON, FEB 4-10.
SLIGHT RISK OF HEAVY SNOW ACROSS PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES,
NORTHERN PLAINS, UPPER MISSISSIPPI VALLEY, AND NORTHERN GREAT LAKES, TUE-SAT,
FEB 4-8.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE PACIFIC NORTHWEST AND
NORTHERN AND CENTRAL CALIFORNIA, TUE-THU, FEB 4-6.
SLIGHT RISK OF HEAVY PRECIPITATION ACROSS PORTIONS OF THE SOUTHERN PLAINS,
LOWER MISSISSIPPI VALLEY, TENNESSEE VALLEY, AND SOUTHEAST, WED-SAT, FEB 5-8.
SLIGHT RISK OF HIGH WINDS ACROSS PORTIONS OF THE WEST COAST AND EXTENDING INTO
THE FOUR CORNERS REGION, TUE-MON, FEB 4-10.
DETAILED SUMMARY
FOR THURSDAY JANUARY 30 - MONDAY FEBRUARY 03:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY FEBRUARY 04 - MONDAY FEBRUARY 10: TROUGHING IS FORECAST ACROSS THE
NORTHWESTERN CONUS DURING WEEK-2 RESULTING IN BELOW-NORMAL TEMPERATURES ALONG
THE WEST COAST AND INTO PARTS OF THE NORTHERN ROCKIES AND NORTHERN PLAINS. THE
MOST ANOMALOUS COLD IS PREDICTED TO BE ACROSS THE PACIFIC NORTHWEST, WITH THE
GEFS GENERALLY ON THE COLDER SIDE OF THE GUIDANCE. THE ECENS PROBABILISTIC
EXTREMES TOOL (PET) DEPICTS AT LEAST A 20 PERCENT CHANCE MINIMUM TEMPERATURES
FALL BELOW THE 15TH CLIMATOLOGICAL PERCENTILE ACROSS THE PACIFIC NORTHWEST,
INCREASING ABOVE 40 PERCENT CLOSER TO THE COAST. THE GEFS PET IS MORE EXPANSIVE
WITH THESE PROBABILITIES AND DEPICTS AT LEAST A 60 PERCENT CHANCE OVER
WASHINGTON AND NORTHWESTERN OREGON. THE UNCALIBRATED 0Z ECENS AND GEFS BOTH
DEPICT SUBFREEZING TEMPERATURES OVER COASTAL AREAS, WITH TEMPERATURES AS LOW AS
20 DEG F IN THE GEFS. A MODERATE RISK OF MUCH BELOW NORMAL TEMPERATURES IS
HIGHLIGHTED ACROSS COASTAL WASHINGTON AND OREGON FEB 4-7 CORRESPONDING WITH THE
LARGEST PREDICTED NEGATIVE TEMPERATURE ANOMALIES AND WHERE COLD WEATHER HAZARDS
CRITERIA IS MOST LIKELY TO BE MET. THE SLIGHT RISK OF MUCH BELOW NORMAL
TEMPERATURES EXTENDS ACROSS THE NORTHERN ROCKIES AND PLAINS FOR ALL OF WEEK-2
WHERE SUBZERO TEMPERATURES ARE POSSIBLE. WHILE THESE TEMPERATURES ARE
CONSIDERABLY COLDER COMPARED TO THE COASTAL PACIFIC NORTHWEST, IT IS LESS
UNCERTAIN IF TEMPERATURES WILL REACH THE VERY COLD CRITERIA ACROSS THESE AREAS,
JUSTIFYING ONLY A SLIGHT RISK.
ALONG WITH THE COLD TEMPERATURES, AN ENHANCED ONSHORE FLOW PATTERN ASSOCIATED
WITH THE TROUGHING FAVORS PERIODS OF HEAVY PRECIPITATION ACROSS THE WEST COAST.
THE INTEGRATED VAPOR TRANSPORT (IVT) TOOL FROM THE ECENS DEPICTS AT LEAST A 50
PERCENT CHANCE IVT VALUES EXCEED 250 KG/M/S ALONG THE OREGON AND CALIFORNIA
COAST EARLY IN WEEK-2, WITH A MUCH WEAKER SIGNAL IN THE GEFS. THE UNCALIBRATED
0Z ECENS DEPICTS A REGION OF HEAVY PRECIPITATION OVER THESE AREAS AT THE
BEGINNING OF THE PERIOD, BUT THE 0Z GEFS IS MUCH DRIER ADDING TO UNCERTAINTY
AND ONLY SUPPORTING A SLIGHT RISK OF HEAVY PRECIPITATION, FEB 4-6. BEYOND THIS
PERIOD, INTERMITTENT CHANCES OF ENHANCED PRECIPITATION ARE LIKELY TO CONTINUE
ACROSS THE WEST COAST, ALTHOUGH THERE IS EVEN MORE UNCERTAINTY WITH THE EXACT
TIMING AND MAGNITUDE. HOWEVER, THE COLD AIR MASS IN PLACE ACROSS THE PACIFIC
NORTHWEST SUPPORTS ENHANCED CHANCES OF HEAVY SNOW OR WINTRY WEATHER EVEN IN LOW
ELEVATION AREAS INCLUDING THE CITIES OF PORTLAND, OR AND SEATTLE, WA.
THEREFORE, A SLIGHT RISK OF HEAVY SNOW IS POSTED ACROSS THESE AREAS, AND FOR
THE HIGHER ELEVATIONS OF THE CASCADES, KLAMATH, AND SIERRA NEVADA MOUNTAINS FOR
THE ENTIRE PERIOD. WITH THE ANOMALOUS TROUGHING AMPLIFYING LOFT, A BROAD SLIGHT
RISK OF HIGH WINDS IS ALSO POSTED ACROSS THE WEST AND INTO THE FOUR CORNERS
REGION FOR ALL OF WEEK-2.
SURFACE LOW PRESSURE IS PREDICTED TO EJECT OUT OF THE TROUGHING OVER THE WEST
BY THE MIDDLE OF WEEK-2, AIDED BY SOME ENHANCED BAROCLINICITY TIED TO
INCREASING MID-LEVEL HIGH PRESSURE OVER THE SOUTHEAST. WHILE THE EXACT TRACK
AND RELATED IMPACTS ARE UNCERTAIN, A SWATH OF HEAVY SNOW CANNOT BE RULED OUT
ACROSS PORTIONS OF THE NORTHERN AND CENTRAL ROCKIES, NORTHERN PLAINS AND UPPER
MIDWEST, WITH THE GEFS SNOW WATER EQUIVALENT (SWE) PET DEPICTING SOME AREAS
WITH AT LEAST A 20 PERCENT CHANCE SWE EXCEEDS THE 85TH CLIMATOLOGICAL
PERCENTILE AND 0.5-INCHES (1-INCH ACROSS THE ROCKIES), AND THE UNCALIBRATED 0Z
ECENS DEPICTING AT LEAST A 20 PERCENT CHANCE FOR SNOWFALL GREATER THAN 4-INCHES
ACROSS THE UPPER MIDWEST DURING THE MIDDLE OF WEEK-2. THEREFORE, A SLIGHT RISK
FOR HEAVY SNOW IS POSTED ACROSS MUCH OF THE NORTHERN TIER, FEB 4-8. BOTH THE
GEFS AND ECENS PETS DEPICT AT LEAST A 20 PERCENT CHANCE 3-DAY PRECIPITATION
EXCEEDS THE 85TH CLIMATOLOGICAL PERCENTILE AND 1-INCH ACROSS PARTS OF THE
SOUTH, ALTHOUGH THESE AREAS ARE PREDICTED TO BE IN THE WARM SECTOR WITH RAIN
THE MOST LIKELY OUTCOME. AS A RESULT, A SLIGHT RISK OF HEAVY PRECIPITATION IS
HIGHLIGHTED ACROSS PORTIONS OF THE SOUTHERN PLAINS, LOWER MISSISSIPPI VALLEY,
TENNESSEE VALLEY, AND SOUTHEAST, FEB 5-8.
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 NORTHWESTERN MAINLAND.
FORECASTER: THOMAS COLLOW
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page