509  
FXHW01 KWNH 260800  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
300 AM EST SAT NOV 26 2022  
 
VALID 00Z SUN NOV 27 2022 - 00Z SUN DEC 04 2022  
 
ONCE AGAIN THE GUIDANCE AGREES FAIRLY WELL THROUGH THE FIRST PART  
OF NEXT WEEK WITH SIGNIFICANT DIFFERENCES AND RUN-TO-RUN  
VARIABILITY THEREAFTER. FLOW AROUND AN INITIAL DEEP-LAYER LOW  
NORTHEAST OF THE STATE WILL SUPPORT RELATIVELY DRY CONDITIONS INTO  
THE WEEKEND. WINDS SHOULD TREND NOTICEABLY WEAKER BY SATURDAY,  
POSSIBLY ALLOWING FOR SOME LAND/SEA BREEZE INFLUENCE ON SHOWER  
ACTIVITY DURING THE WEEKEND. CONSENSUS MAINTAINS A PRONOUNCED  
NORTHWARD SURGE OF TROPICAL MOISTURE AND ENERGY ALOFT BY AROUND  
LATE SUNDAY THROUGH TUESDAY, WITH PRECIPITABLE WATER VALUES  
POSSIBLY REACHING AT LEAST 2.0 INCHES AT SOME LOCATIONS (WITH  
BETTER 00Z GFS/ECMWF AGREEMENT THAN SEEN 24 HOURS AGO).  
STANDARDIZED ANOMALIES IN THE GFS/ECMWF AND THEIR MEANS REACH PLUS  
2.5-4. GUIDANCE GENERALLY AGREES ON A HEAVY RAINFALL THREAT BUT  
WITH TYPICAL SPREAD FOR THE SPECIFICS. ENOUGH SOUTHEASTERLY  
BACKGROUND FLOW MAY EXIST AT LOW LEVELS TO PROVIDE THE BEST  
ENHANCEMENT OVER FAVORED TERRAIN ON THE BIG ISLAND, BUT OTHER  
LOCATIONS COULD SEE MEANINGFUL RAINFALL TOTALS AS WELL.  
 
BY MID-LATE WEEK THE GUIDANCE, IF ANYTHING, HAS BECOME EVEN MORE  
DIVERSE THAN YESTERDAY WITH RESPECT TO THE POSSIBLE UPPER PATTERN  
OVER AND NEAR THE ISLANDS ALONG WITH THE RESULTING SURFACE PATTERN  
AND MOISTURE LEVELS. THE ONE POSITIVE TREND FROM YESTERDAY IS  
THAT THE 00Z GFS HAS FINALLY HEDGED BACK SOME ON THE AMOUNT OF  
MOISTURE LINGERING OVER OR RETURNING ACROSS THE ISLANDS. STILL,  
THERE IS ENOUGH UPPER TROUGHING JUST WEST OF THE STATE IN THE  
GFS/GEFS MEAN (AND SUFFICIENTLY CLOSE PROXIMITY OF A SURFACE  
FRONT) TO KEEP FAIRLY HIGH PRECIPITABLE WATER VALUES OVER THE AREA  
OR AT LEAST THE FAR WESTERN ISLANDS FOR MOST OF THE PERIOD. ON  
THE OTHER HAND THE 00Z ECMWF UPPER PATTERN IS SHIFTED FAR ENOUGH  
WEST THAT SHORTWAVE ENERGY DROPPING DOWN THE EAST SIDE OF THE  
RIDGE AXIS ACTUALLY LEADS TO A SIGNIFICANT DRYING TREND FROM THE  
NORTH. THE 12Z ECMWF MEAN IS NOT AS EXTREME WITH THE DRYING TREND  
BUT IS STILL A LOT DRIER THAN THE GFS/GEFS MEAN. SOMEWHERE  
BETWEEN THESE EXTREMES, EXPECT A GRADUAL REDUCTION IN MOISTURE AND  
RAINFALL WITH TIME ALONG WITH THE EVENTUAL RETURN OF AT LEAST  
LIGHT TRADE WINDS.  
 
RAUSCH  
 

 
 
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