005  
FXHW01 KWNH 120750  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
249 AM EST THU DEC 12 2024  
 
VALID 00Z FRI DEC 13 2024 - 00Z FRI DEC 20 2024  
 
LATEST GUIDANCE REMAINS IN GOOD AGREEMENT WITH MOST ASPECTS OF THE  
FORECAST. STRONG TRADES CONTINUING INTO THURSDAY SHOULD GRADUALLY  
SLACKEN SOME AS A SERIES OF FRONTS WILL WEAKEN THE SURFACE RIDGE  
AND PUSH IT SOUTH, POSSIBLY REACHING THE MAIN ISLANDS BY AROUND  
TUESDAY OR WEDNESDAY. AS THE SURFACE PATTERN CHANGES, PRIMARILY  
WINDWARD/MOUNTAIN SHOWER FOCUS WILL LIKELY TRANSITION TOWARD MORE  
SEA BREEZE INFLUENCE BY TUESDAY-WEDNESDAY. GUIDANCE STILL SHOWS  
THE HIGHEST RAINFALL TOTALS DURING THURSDAY-FRIDAY WHEN THE BIG  
ISLAND IN PARTICULAR WILL BE ON THE NORTHERN FRINGE OF ENHANCED  
PRECIPITABLE WATER VALUES AS AN UPPER LOW RETROGRADES WELL SOUTH  
OF THE STATE. MOISTURE SHOULD DECREASE BELOW CLIMATOLOGICAL  
VALUES BY THE WEEKEND, FAVORING MUCH LIGHTER SHOWERS. WITH  
TYPICAL DIFFERENCES IN SPECIFICS, GUIDANCE MAINTAINS THE IDEA THAT  
SOME INCREASE OF MOISTURE SHOULD MOVE INTO THE BIG ISLAND AND  
VICINITY FROM THE SOUTHEAST BY NEXT TUESDAY-WEDNESDAY. HOWEVER  
RAINFALL SHOULD REMAIN FAIRLY LIGHT GIVEN NEARBY STRONG UPPER  
RIDGING. BY THURSDAY MOST SOLUTIONS SHOW A COLD FRONT AND  
ASSOCIATED MOISTURE BAND REACHING VERY CLOSE OR INTO THE MAIN  
ISLANDS. ALTHOUGH THE GFS/GEFS ARE A BIT MORE AMPLIFIED WITH THE  
SUPPORTING UPPER SHORTWAVE VERSUS THE ECMWF/CMC AND THEIR MEANS  
(LEADING TO THE GFS/GEFS FRONT REACHING FARTHER SOUTH), SOME  
MACHINE LEARNING MODELS LEAN AT LEAST AS FAR AS THE GFS SCENARIO.  
AN EVEN COMPROMISE SEEMS TO PROVIDE A GOOD STARTING POINT FOR A  
SPECIFIC FORECAST GIVEN TYPICAL PREDICTABILITY SEVEN DAYS OUT IN  
TIME.  
 
RAUSCH  
 
 
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