201  
FXHW01 KWNH 190722  
PMDHI  
 
HAWAII EXTENDED FORECAST DISCUSSION  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
321 AM EDT FRI MAY 19 2023  
 
VALID 00Z SAT MAY 20 2023 - 00Z SAT MAY 27 2023  
   
..A WET PATTERN FOR HAWAII TO LINGER INTO THE WEEKEND
 
 
A FAVORED GUIDANCE COMOSITE INDICATES THAT A WET PATTERN FOR  
HAWAII WILL LINGER INTO THE WEEKEND AS AN UPPER TROUGH MOVES  
SLOWLY ACROSS THE STATE. ANOMALOUSLY HIGH TROPICAL MOISTURE IS  
STREAMING IN WITH THE DEEP SOUTHERLY FLOW WITH/AHEAD OF THIS  
FEATURE, PROVIDING FOR WIDESPREAD RAIN. THIS IS QUITE EVIDENT IN  
LATEST BLENDED PRECIPITABLE WATER SATELLITE LOOPS AND AS PER AN  
ACTIVE ONGOING RADAR LOOP SIGNATURE. SOME THUNDERSTORMS MAY BE  
POSSIBLE AS THE TROUGH ALOFT COULD LESSEN OR OR ELIMINATE THE  
TYPICAL INVERSION AND PROVIDE INSTABILITY, BUT A LIMITING FACTOR  
FOR STRONG STORMS COULD BE THE WIDESPREAD CLOUD COVER REDUCING  
SURFACE HEATING. REGARDLESS, ENHANCED RAINFALL TOTALS THAT MAY  
LEAD TO LOCAL RUNOFF ISSUES ARE MOST LIKELY TODAY INTO SATURDAY.  
 
SHOWER COVERAGE SHOULD GRADUALLY DECREASE THROUGH THE WEEKEND INTO  
EARLY NEXT WEEK AS THE WEAKENING UPPER TROUGH MOVES AWAY AND IS  
INCREASINGLY REPLACED BY UPPER RIDGING. THIS WILL SHIFT THE  
MOISTURE PLUME AWAY FROM THE STATE NEXT WEEK WHILE SURFACE HIGHS  
BUILD TO THE NORTHEAST AND THE NORTHWEST OVER THE ISLANDS ACROSS  
THE MID-LATITUDES OF THE PACIFIC, CREATING A MORE TYPICAL AND  
DRIER EASTERLY TRADE WIND PATTERN. TRADES MAY INCREASE TO BREEZY  
LEVELS AT TIMES NEXT WEEK, AND SHOWERS THAT DO FORM SHOULD FOCUS  
ACROSS WINDWARD AND MOUNTAIN AREAS. THERE IS A GROWING BUT STILL  
UNCERTAIN GUIDANCE SIGNAL THAT FAVORS SLOW CARVING OF AN UPPER  
WEAKNESS OF THE STATE FOR MID-LATER NEXT WEEK THAT COULD AGAIN  
POOL SHOWER FUELING MOISTURE.  
 
SCHICHTEL  
 

 
 
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