318
FXUS21 KWNC 181940
PMDTHR
US HAZARDS OUTLOOK
NWS CLIMATE PREDICTION CENTER COLLEGE PARK MD
300 PM EST FEBRUARY 18 2025
SYNOPSIS: SURFACE HIGH PRESSURE OVER THE GREAT BASIN AND LOW PRESSURE OVER THE
COLORADO RIVER DELTA CREATE CONDITIONS FAVORABLE FOR SANTA ANA WINDS OVER
SOUTHERN CALIFORNIA AT THE OUTSET OF WEEK-2. MULTIPLE MODEL ENSEMBLES DEPICT
DEVELOPING LOW PRESSURE OVER THE GREAT PLAINS, INCREASING CHANCES FOR HIGH
WINDS TO PORTIONS OF THE NORTHERN CONTIGUOUS U.S. (CONUS).
HAZARDS
SLIGHT RISK OF HIGH WINDS FOR PORTIONS OF COASTAL SOUTHERN CALIFORNIA, WED-THU,
FEB 26-27.
SLIGHT RISK OF EPISODIC HIGH WINDS FOR PORTIONS OF THE NORTHERN AND CENTRAL
PLAINS, WED-TUE, FEB 26-MAR 4.
DETAILED SUMMARY
FOR FRIDAY FEBRUARY 21 - TUESDAY FEBRUARY 25:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
FOR WEDNESDAY FEBRUARY 26 - TUESDAY MARCH 04: MODEL ENSEMBLE SOLUTIONS OF
500-HPA GEOPOTENTIAL HEIGHTS FROM THE GEFS, ECENS, AND CMCE GENERALLY AGREE ON
A GRADUAL TRANSITION TOWARDS ZONAL FLOW OVER THE CONUS DURING THE WEEK-2
PERIOD, WITH WEAK POSITIVE HEIGHT ANOMALIES OVER THE WEST COAST AND BROAD BUT
WEAK TROUGHING OVER THE EAST. THIS IS FAVORED TO BRING MILDER TEMPERATURES TO
MUCH OF THE CONUS AND A RELATIVELY QUIET WEEK-2 FORECAST PERIOD FROM A HAZARDS
PERSPECTIVE.
AT THE OUTSET OF WEEK-2 MULTIPLE MODEL ENSEMBLES DEPICT A STRONG SURFACE HIGH
PRESSURE OVER THE GREAT BASIN AND AN INVERTED TROUGH ALONG THE COAST OF
SOUTHERN CALIFORNIA, A SETUP FAVORABLE FOR SANTA ANA WINDS. THIS FEATURE IS
SHORT-LIVED BUT WELL-DEFINED IN ENSEMBLE MEANS, TRANSLATING TO THE GEFS AND
ECMWF MEMBER SOLUTIONS SHOWING AN UPTICK IN MAXIMUM WIND SPEEDS EARLY IN
WEEK-2. THEREFORE A SLIGHT RISK (20 TO 40 % CHANCE) OF HIGH WINDS IS POSTED FOR
COASTAL PORTIONS OF SOUTHERN CALIFORNIA FOR FEB 26-27.
MODEL SOLUTIONS FEATURE TIGHT PRESSURE GRADIENTS ALONG THE EASTERN FRONT OF THE
ROCKIES, WHERE THEY INDICATE THE POTENTIAL FOR LEE CYCLOGENESIS OVER THE GREAT
PLAINS DURING THE WEEK-2 PERIOD. THE GEFS AND ECMWF PETS ARE LESS BULLISH THAN
YESTERDAY BUT BOTH CONTINUE TO INDICATE AT LEAST A 20% PROBABILITY OF MAXIMUM
WIND SPEED EXCEEDING THE 85TH PERCENTILE OVER PORTIONS OF THE GREAT PLAINS
THROUGHOUT WEEK-2. A SLIGHT RISK OF EPISODIC HIGH WIND IS POSTED FOR PORTIONS
OF THE NORTHERN AND CENTRAL PLAINS FOR FEB 26-MAR 4, WHERE MODEL AGREEMENT IS
BEST. THE PETS ALSO INDICATE THE POTENTIAL FOR IMPACTFUL PRECIPITATION AND/OR
WIND TO AFFECT THE LOWER MISSISSIPPI VALLEY LATE IN WEEK-2, HOWEVER UNCERTAINTY
IS VERY HIGH SO NO ASSOCIATED HAZARDS ARE POSTED AT THIS TIME.
DEEP LOW PRESSURE OVER THE NORTH PACIFIC DISCUSSED ABOVE IS EXPECTED TO LEAD TO
MOIST ONSHORE FLOW FOR SOUTHEASTERN ALASKA. THE PETS INDICATE A MODEST
POTENTIAL FOR 3-DAY PRECIPITATION TOTALS TO EXCEED THE 85TH PERCENTILE.
HOWEVER, ACCUMULATION TOTALS ARE NOT EXPECTED TO EXCEED HAZARDOUS CRITERIA SO
NO ASSOCIATED HAZARD IS POSTED AT THIS TIME. HERE IS, HOWEVER, AN INCREASED
POTENTIAL FOR LANDSLIDES IN THE REGION GIVEN COPIOUS ANTECEDENT RAINFALL AND
WARMER THAN AVERAGE TEMPERATURES RESULTING IN HIGHER THAN NORMAL SNOW LEVELS.
THE ECMWF AND GEFS PETS FOR MINIMUM TEMPERATURE BOTH INDICATE A WEAK SIGNAL FOR
MUCH BELOW NORMAL TEMPERATURES FOR PORTIONS OF THE NORTHEAST U.S. FOR FEB
27-28. TEMPERATURES ARE NOT EXPECTED TO DIP BELOW ADVISORY CRITERIA SO NO
ASSOCIATED HAZARD IS POSTED AT THIS TIME.
FORECASTER: DANNY BARANDIARAN
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