369
FXUS21 KWNC 201908
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST JANUARY 20 2025
SYNOPSIS: A MAJOR TEMPERATURE CHANGE IS FORECAST BY THE END OF JANUARY WITH
NEAR TO ABOVE-NORMAL TEMPERATURES FAVORED FOR A MAJORITY OF THE LOWER 48 STATES
WHILE ANOMALOUSLY COLD TEMPERATURES PREVAIL ACROSS ALASKA. A TRANSITION TO A
MORE ZONAL FLOW PATTERN IS ANTICIPATED WHICH LOWERS THE RISK OF ANY WIDESPREAD,
HIGH IMPACT WINTER STORMS. HOWEVER, A LOW PRESSURE SYSTEM IS EXPECTED TO BRING
AN INCREASED CHANCE OF HEAVY SNOW TO SOUTHERN COLORADO, NEW MEXICO, AND THE
TEXAS PANHANDLE FROM JANUARY 28 TO 30. BEGINNING ON JANUARY 30, ENHANCED
ONSHORE FLOW IS FORECAST TO RESULT IN PERIODS OF SNOW, POTENTIALLY HEAVY, TO
THE CASCADES AND NORTHERN ROCKIES. OFFSHORE WINDS ARE EXPECTED TO RETURN TO
SOUTHERN CALIFORNIA NEXT WEEK AS SURFACE HIGH PRESSURE BECOMES CENTERED OVER
THE GREAT BASIN.
HAZARDS
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR PARTS OF INTERIOR WESTERN AND
CENTRAL ALASKA, TUE-MON, JAN 28-FEB 3.
SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES FOR NEW ENGLAND AND PARTS OF NEW
YORK, WED-FRI, JAN 29-31.
SLIGHT RISK OF HEAVY SNOW FOR PARTS OF SOUTHERN COLORADO, NEW MEXICO, AND THE
TEXAS PANHANDLE, TUE-THU, JAN 28-30.
SLIGHT RISK OF HEAVY SNOW FOR THE NORTHERN CASCADES AND NORTHERN ROCKIES,
THU-MON, JAN 30-FEB 3.
SLIGHT RISK OF HIGH WINDS FOR SOUTHERN CALIFORNIA, TUE-FRI, JAN 28-31.
DETAILED SUMMARY
FOR THURSDAY JANUARY 23 - MONDAY JANUARY 27:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR TUESDAY JANUARY 28 - MONDAY FEBRUARY 03: FOLLOWING AN ARCTIC OUTBREAK THIS
WEEK ACROSS THE EASTERN TWO THIRDS OF THE CONTIGUOUS U.S. (CONUS), TEMPERATURES
ARE LIKELY TO MODERATE PRIOR TO WEEK-2. THE GEFS AND ECENS ARE IN GOOD
AGREEMENT AND REMAIN CONSISTENT THAT NEGATIVE (POSITIVE) 500-HPA HEIGHT
ANOMALIES BECOME ESTABLISHED OVER THE HIGH (MIDDLE) LATITUDES OF NORTH AMERICA.
THIS POSITIVE ARCTIC OSCILLATION IS FORECAST BY THE GEFS TO PERSIST INTO THE
BEGINNING OF FEBRUARY. THE MADDEN-JULIAN OSCILLATION (MJO) IS FORECAST TO
PROPAGATE EASTWARD FROM THE INDIAN OCEAN TO THE MARITIME CONTINENT DURING THE
NEXT TWO WEEKS AND THIS MJO EVOLUTION TYPICALLY CORRESPONDS TO BELOW-NORMAL
TEMPERATURES ACROSS ALASKA WITH ABOVE-NORMAL TEMPERATURES MORE PREVALENT
THROUGHOUT MUCH OF THE CONUS. MODEL GUIDANCE IS CONSISTENT WITH THIS
TEMPERATURE PATTERN DURING WEEK-2. THE GEFS AND ECENS PROBABILITIES EXTREME
TOOLS (PETS) DEPICT MINIMUM TEMPERATURES HAVING MORE THAN A 20 PERCENT CHANCE
OF MINIMUM TEMPERATURES FALLING BELOW THE 15TH PERCENTILE AND NEAR OR BELOW -20
DEGREES F, WHICH SUPPORTS AT LEAST A SLIGHT RISK OF MUCH BELOW-NORMAL
TEMPERATURES FOR PORTIONS OF INTERIOR WESTERN AND CENTRAL ALASKA. ALSO, STRONG
SURFACE HIGH CENTERED OVER NORTHEASTERN SIBERIA COUPLED WITH A SURFACE LOW
ACROSS THE GULF OF ALASKA IS EXPECTED TO RESULT IN ENHANCED WINDS ESPECIALLY
EARLY IN WEEK-2. THESE ENHANCED WINDS MAY CAUSE WIND CHILL VALUES TO APPROACH
OR EXCEED THE COLD TEMPERATURE CRITERIA OF -40F AND -55F ACROSS SOUTHERN AND
CENTRAL ALASKA, RESPECTIVELY.
EARLY IN WEEK-2, THE ENSEMBLE MEANS DEPICT A 500-HPA TROUGH AMPLIFYING OVER
SOUTHEASTERN CANADA AND THE NORTHEASTERN CONUS WHICH IS LIKELY TO PROMOTE
ANOTHER SURGE OF ARCTIC AIR. A SLIGHT RISK OF MUCH BELOW-NORMAL TEMPERATURES,
VALID JANUARY 29-31, IS POSTED FOR PARTS OF NEW YORK AND NEW ENGLAND WHERE THE
GEFS AND ECENS DEPICT MINIMUM TEMPERATURES HAVING A 20 PERCENT CHANCE OF
FALLING BELOW THE 15TH PERCENTILE AND BELOW -10 DEGREES F. GUSTY NORTHWEST
WINDS COULD LEAD TO WIND CHILL VALUES BELOW -20 DEGREES F IN THE DESIGNATED
TEMPERATURE HAZARD. BY THE BEGINNING OF FEBRUARY, TEMPERATURES ARE FORECAST TO
RAPIDLY MODERATE AS THE ANOMALOUS 500-HPA TROUGH SHIFTS EASTWARD.
A SHORTWAVE TROUGH IN THE SOUTHERN STREAM IS EXPECTED TO TRACK EASTWARD FROM
THE SOUTHWEST TO THE SOUTHERN GREAT PLAINS. BASED ON THE ECENS (NEAR A 20
PERCENT CHANCE OF SNOWFALL AMOUNTS EXCEEDING 4 INCHES) AND THE GEFS PET WITH
MORE THAN A 20 PERCENT CHANCE OF SNOW WATER EQUIVALENT (SWE) VALUES ABOVE THE
85TH PERCENTILE, A SLIGHT RISK OF HEAVY SNOW IS POSTED FROM SOUTHERN COLORADO
AND NEW MEXICO EAST TO THE TEXAS PANHANDLE.
BEGINNING ON JANUARY 30 AND THROUGH THE END OF WEEK-2, THE GEFS AND ECENS FAVOR
ENHANCED ONSHORE FLOW INTO WASHINGTON, IDAHO, AND MONTANA WHICH MAY RESULT IN
PERIODS OF HEAVY SNOW FOR THE NORTHERN CASCADES AND NORTHERN ROCKIES. THE
SLIGHT RISK OF HEAVY SNOW IS CONSISTENT WITH WHERE THE GEFS PET HAS A 20
PERCENT CHANCE THAT 3-DAY SWE TOTALS EXCEED THE 85TH PERCENTILE AND 1 INCH,
LIQUID EQUIVALENT.
BY JANUARY 28 AND CONTINUING THROUGH THE END OF JANUARY, THE 12Z GEFS DEPICTS
ANOMALOUS SURFACE HIGH PRESSURE RETURNING TO THE GREAT BASIN. THIS WOULD FAVOR
OFFSHORE FLOW ACROSS SOUTHERN CALIFORNIA WITH AN ELEVATED CHANCE OF SANTA ANA
WINDS. THEREFORE, A SLIGHT RISK OF HIGH WINDS IS DESIGNATED FOR SOUTHERN
CALIFORNIA. THE LACK OF A PREDICTED HIGH AMPLITUDE 500-HPA RIDGE NEAR THE WEST
COAST PRECLUDES THE DESIGNATION OF A MODERATE RISK AT THIS TIME.
FORECASTER: BRAD PUGH
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