940  
FXHW01 KWNH 170756  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
355 AM EDT TUE OCT 17 2023  
 
VALID 00Z WED OCT 18 2023 - 00Z WED OCT 25 2023  
 
FAIRLY LIGHT TRADES WILL PREVAIL THROUGH MIDWEEK, ALLOWING FOR  
LAND/SEA BREEZE INFLUENCE ON SHOWERS WHEREVER THE BACKGROUND FLOW  
IS TOO WEAK TO PROMOTE A MORE TYPICAL WINDWARD FOCUS. A FRONT  
REACHING THE NORTHWESTERN ISLANDS AFTER MIDWEEK SHOULD BRING A  
NARROW AXIS OF MOISTURE INTO THE AREA WITH SOME INCREASE OF  
RAINFALL. LATEST MODEL RUNS SUGGEST THAT THIS MOISTURE AXIS MAY  
BREAK UP BY THE WEEKEND. MEANWHILE HIGH PRESSURE TO THE NORTH OF  
THE FRONT MAY HELP TRADES TO REBOUND BRIEFLY AROUND  
THURSDAY-FRIDAY.  
 
GUIDANCE CONTINUES TO SHOW SIGNIFICANT TROUGH AMPLIFICATION (WITH  
EMBEDDED UPPER LOW) TO THE NORTH AND WEST OF THE STATE AROUND  
SATURDAY-MONDAY, PERHAPS BEGINNING TO LIFT OUT TUESDAY. THE  
ASSOCIATED SURFACE FRONT WILL APPROACH FROM THE NORTHWEST AND  
SUPPORT SOUTHEASTERLY TO SOUTHERLY WINDS ACROSS THE STATE, LIKELY  
PULLING UP INCREASING MOISTURE FROM LOWER LATITUDES. THERE IS  
STILL SOME SPREAD FOR SPECIFICS, INCLUDING THE PRECISE LOCATION OF  
THE ENHANCED MOISTURE AXIS, BUT TODAY'S MODELS AND MEANS ARE  
NOTICEABLY BETTER CLUSTERED THAN YESTERDAY FOR SURFACE AND UPPER  
LEVEL DETAILS. THE 00Z ECMWF IS SOMEWHAT DEEPER THAN OTHER  
GUIDANCE WITH THE UPPER TROUGH AROUND MONDAY-TUESDAY, POTENTIALLY  
PLAYING A ROLE IN ITS FORECAST OF MUCH HEAVIER RAINFALL OVER THE  
CENTRAL ISLANDS NEXT TUESDAY. ON THE OTHER HAND, SOME OTHER MODEL  
RUNS COULD BE UNDERDONE WITH RAINFALL TO SOME DEGREE GIVEN THE  
RELATIVE CONSENSUS AMONG GFS/ECMWF AND ENSEMBLE MEAN RUNS TOWARD  
HIGHER PRECIPITABLE WATER VALUES BY LATE MONDAY/TUESDAY.  
 
RAUSCH  
 

 
 
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