934  
FXHW01 KWNH 031222  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
721 AM EST SAT FEB 03 2018  
 
VALID 00Z SUN FEB 04 2018 - 00Z SUN FEB 11 2018  
 
...LOCALLY HEAVY RAIN FOR NORTHWEST ISLANDS THROUGH THE WEEKEND  
THEN THROUGH THE REST OF THE ISLANDS EARLY NEXT WEEK...  
 
VERY DEEP TROUGHING NEAR THE DATELINE (500MB HEIGHT ANOMALIES  
AROUND -3 STANDARD DEVIATIONS) WILL MOVE EASTWARD OVER THE  
WEEKEND, DRIVING A SURFACE COLD FRONT THROUGH THE REGION STARTING  
EARLY MONDAY OVER KAUAI AND NI'IHAU. THE MODELS HAVE TRENDED  
TOWARD A BIT SLOWER FRONTAL PASSAGE OWING TO A STRONGER UPPER  
SHORTWAVE (POSSIBLY CLOSING OFF) AND A COUPLE SURFACE WAVES (EVEN  
UP THROUGH 850-800MB) FORMING ALONG THE COLD FRONT AND LIFTING  
NORTHEASTWARD. WITH AVAILABLE MOISTURE WELL ABOVE AVERAGE  
(1.50-1.75" PRECIPITABLE WATER) THE HEAVY RAIN THREAT WILL  
TRANSLATE EASTWARD THROUGH THE ISLAND CHAIN MONDAY-TUESDAY AND  
MAYBE INTO EARLY WEDNESDAY. MODELS/ENSEMBLES SHOW THE COLD FRONT  
EXITING PAST THE BIG ISLAND LATE WEDNESDAY OR EARLY THURSDAY AS  
THE UPPER TROUGH FINALLY SWINGS THROUGH. NORTHWESTERLY UPPER FLOW  
WILL FOLLOW IN THE WAKE OF THE FROPA AS SURFACE WINDS VEER TO  
NORTHWESTERLY BEHIND THE FRONT THEN NORTHERLY TO NORTHEASTERLY. A  
SHOWERY AND BREEZY PATTERN FOR THE ISLANDS WILL FOLLOW LATER NEXT  
WEEK INTO NEXT WEEKEND WITH THE UPPER LOW AND SURFACE FRONT EAST  
OF THE REGION. GFS/ECMWF BLENDED SOLUTION SHOULD SUFFICE THROUGH  
THE PERIOD GIVEN THE SHIFTS IN THE GUIDANCE OVER THE PAST 24-48  
HOURS.  
 
FRACASSO  
 

 
 
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