701  
FXHW01 KWNH 181208  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
708 AM EST SAT NOV 18 2017  
 
VALID 00Z SUN NOV 19 2017 - 00Z SUN NOV 26 2017  
 
MODELS AGREE IN PRINCIPLE THAT MEAN TROUGHING ALOFT OVER AND  
NORTHEAST OF THE STATE THROUGH THE PERIOD WILL KEEP PRECIPITABLE  
WATER VALUES WELL BELOW CLIMATOLOGICAL LEVELS, WITH SOME MODEST  
FLUCTUATION IN RESPONSE TO INDIVIDUAL SHORTWAVES WITHIN THE MEAN  
TROUGH. AS A RESULT EXPECT WINDWARD-FOCUSED (BUT OCCASIONALLY  
STRAYING TO LEEWARD LOCATIONS) SHOWER ACTIVITY TO BE ON THE  
LIGHTER SIDE OF THE SPECTRUM.  
 
THE STRONGEST FEATURE TO AFFECT THE ISLANDS' WEATHER WILL BE FROM  
NOW INTO EARLY NEXT WEEK, AN UPPER TROUGH AND SURFACE LOW TO THE  
NORTHEAST OF THE AREA. GUIDANCE AGREES THAT LOWEST HEIGHTS ALOFT  
WILL PASS OVER THE STATE AROUND SUNDAY FOLLOWED BY NORTHEASTWARD  
PROGRESSION OF THE SHORTWAVE. THE ASSOCIATED COLD FRONT IS  
CURRENTLY CROSSING THE REGION AND WILL REMAIN TO THE EAST AFTER  
PASSAGE. THE FLOW BETWEEN THE SURFACE LOW AND CENTRAL PACIFIC  
HIGH PRESSURE WILL LEAD TO BRISK WINDS GENERALLY FROM THE  
NORTHWEST OR NORTH INTO THE FIRST PART OF NEXT WEEK. THEN FROM  
MIDWEEK ONWARD THE SURFACE HIGH SHOULD EXTEND FAR ENOUGH SOUTHEAST  
TO RETURN WINDS TO A MORE TYPICAL NORTHEASTERLY OR EASTERLY  
ORIENTATION. A FAIRLY TIGHT PRESSURE GRADIENT WILL LIKELY KEEP  
WINDS ON THE BRISK/STRONG SIDE INTO NEXT WEEKEND. THERE IS  
REASONABLE MODEL/ENSEMBLE AGREEMENT ON THE SURFACE PATTERN THROUGH  
THURSDAY-SATURDAY THOUGH LOW-PREDICTABILITY DETAIL DIFFERENCES  
ALOFT DEVELOP.  
 
RAUSCH  
 

 
 
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