835  
FXHW01 KWNH 181213  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
811 AM EDT WED OCT 18 2017  
 
VALID 00Z THU OCT 19 2017 - 00Z THU OCT 26 2017  
 
BREEZY TRADES WILL SLOWLY SUBSIDE BY THE WEEKEND AS A 1034MB  
SURFACE HIGH MOVES SOUTHEASTWARD AND THEN EASTWARD ALONG 33N LATER  
THIS WEEK BUT WEAKENS TO ABOUT 1026MB. GENERALLY LIGHT  
WINDWARD/MAUKA SHOWERS ARE EXPECTED. NEXT WEEK, A TROUGH IS  
FORECAST TO DIG PAST 165W NORTH OF 35N BUT THE ENSEMBLES DIVERGE  
ON WHETHER TO CONTINUE DIGGING IT TO/SOUTH OF 30N OR BEGIN TO LIFT  
IT BACK EASTWARD THEN NORTHEASTWARD. THE GFS/CANADIAN WERE MOST  
AGGRESSIVE WITH THIS SYSTEM WHILE THE 00Z ECMWF WAS  
QUICKER/WEAKER. THE MULTI-CENTER ENSEMBLES WERE EXTENDED EVEN  
FARTHER SOUTHWEST (DEEPER/SLOWER) AND NORTHEAST (QUICKER/WEAKER)  
THAN THE DETERMINISTIC MODELS, BUT AN OVERALL CONSENSUS SEEMS TO  
BE NEAR THE 00Z OR 06Z GEFS MEAN WHICH IS CLOSER TO THE 00Z ECMWF  
IN THE SUBTROPICAL CENTRAL PACIFIC (THOUGH NOT AS CLOSE IN THE  
NORTHEAST PACIFIC). THIS WOULD ALLOW THE COLD FRONT TO DROP  
SOUTHEASTWARD VERY CLOSE TO THE NORTHWESTERN ISLANDS AND ALSO  
ALLOW SOUTHEASTERLY FLOW IN THE LOW LEVELS TO BRING IN MORE  
MOISTURE. MORE WIDESPREAD RAIN WOULD BE A POSSIBILITY GIVEN  
INSTABILITY/LIFT INCREASING AS WELL.  
 
FRACASSO  
 

 
 
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