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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