574  
FXHW60 PHFO 072006  
AFDHFO  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE HONOLULU HI  
1006 AM HST TUE JUL 7 2020  
   
SYNOPSIS
 
 
STRENGTHENING TRADE WINDS WILL PERSIST THROUGH THE WEEKEND.  
SHOWERS EMBEDDED WITHIN THE TRADE WIND FLOW WILL BE FOCUSED OVER  
THE WINDWARD SIDES OF THE ISLANDS, PRIMARILY DURING THE NIGHTS AND  
EARLY MORNING HOURS. ADDITIONAL SHOWERS WILL BE LIKELY OVER THE  
LEEWARD SLOPES OF THE BIG ISLAND DURING THE AFTERNOON HOURS.  
 

 
   
DISCUSSION
 
 
A 1033 MB SURFACE HIGH IS CENTERED 1300 MILES NORTH NORTHEAST OF  
HAWAII AND IS DRIVING FRESH TRADE WINDS ACROSS THE STATE. 12Z  
SOUNDINGS FROM HILO AND LIHUE SHOW A MIDLEVEL INVERSION OVER THE  
AREA BETWEEN 7000 AND 9000 FEET WITH NEAR NORMAL PRECIPITABLE  
WATER VALUES AROUND 1.2 INCHES. VISIBLE SATELLITE AND RADAR SHOW  
LOW CLOUDS AND SHOWERS CARRYING OVER THE ISLANDS BY THE TRADE  
WINDS. SHOWERS ARE FOCUSED OVER WINDWARD AND MAUKA AREAS, OCCASIONALLY  
SPILLING ONTO LEEWARD SIDES OF THE SMALLER ISLANDS. RAINFALL  
MAXIMUMS WILL OCCUR DURING THE NIGHTS AND EARLY MORNINGS, WITH THE  
EXCEPTION OF THE KONA SLOPES OF THE BIG ISLAND (AFTERNOONS).  
 
AN UPPER LEVEL LOW TO THE NORTHEAST OF THE ISLANDS IS EXPECTED TO  
LIFT FURTHER AWAY OVER THE NEXT SEVERAL DAYS. SOME MIDLEVEL  
RIDGING WILL FILL IN BY WEDNESDAY, WHICH COULD HELP TO SHOWER  
ACTIVITY INTO THURSDAY. HEADING INTO THIS WEEKEND, A MID TO UPPER  
LEVEL LOW IS FORECAST TO MOVE TOWARDS THE ISLANDS. THIS FEATURE  
COULD BRING AN INCREASE IN WINDS TO HALEAKALA AND THE BIG ISLAND  
SUMMITS DURING THE END OF THE WEEKEND AND THE BEGINNING PART OF  
NEXT WEEK. SHOWERS COULD ALSO INCREASE DEPENDING UPON HOW CLOSE  
THE LOW NEARS HAWAII.  
 

 
   
AVIATION
 
 
HIGH PRESSURE WELL NORTH OF THE STATE WILL GENERATE MODERATE TO  
LOCALLY BREEZY TRADE WINDS OVER THE NEXT SEVERAL DAYS. SPEEDS  
WILL RAMP UP THROUGH TONIGHT AND WILL LIKELY REQUIRE ISSUANCE OF  
AIRMET TANGO FOR LOW-LEVEL TURBULENCE LATER THIS AFTERNOON OR  
EVENING.  
 
SCATTERED SHOWERS WILL AFFECT MAINLY THE WINDWARD COASTS AND  
SLOPES, THOUGH A FEW SHOWERS MAY BE PUSHED OVER TO LEEWARD AREAS  
AT TIMES. PERIODS OF MVFR CONDITIONS ARE EXPECTED DUE TO LOWERED  
CEILINGS AND DECREASED VISIBILITY IN THE SHOWERS, THOUGH NOT  
WIDESPREAD ENOUGH FOR EXTENSIVE MOUNTAIN OBSCURATION.  
 

 
   
MARINE
 
 
FRESH TO STRONG TRADE WINDS WILL PREVAIL THROUGH THE WEEK AS  
STRONG HIGH PRESSURE HOLDS FAR NORTH AND NORTHEAST OF THE  
ISLANDS. A SMALL CRAFT ADVISORY (SCA) IS IN EFFECT FOR THE  
TYPICALLY WINDIER WATERS AROUND MAUI COUNTY AND THE BIG ISLAND  
THROUGH TOMORROW, AND WILL ALMOST CERTAINLY NEED TO BE EXTENDED  
THROUGH THE WEEK.  
 
NO SIGNIFICANT SWELLS ARE DUE THROUGH MUCH OF THE WEEK. A MIX OF  
MAINLY BACKGROUND SWELLS FROM THE SOUTHWEST AND SOUTHEAST WILL  
DOMINATE, WITH A SOUTH-SOUTHWEST SWELL POTENTIALLY BOOSTING SOUTH  
SHORE SURF TO AROUND SUMMERTIME AVERAGE ON THURSDAY AND FRIDAY.  
TRADE WIND SWELL WILL GRADUALLY BUILD TO AROUND SUMMERTIME AVERAGE  
BY THURSDAY OR FRIDAY, THEN HOLD INTO EARLY NEXT WEEK. SURF ALONG  
NORTH FACING SHORES WILL REMAIN SMALL.  
 

 
   
HFO WATCHES/WARNINGS/ADVISORIES
 
 
SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR MAALAEA BAY-  
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG  
ISLAND SOUTHEAST WATERS.  
 

 
 

 
 
DISCUSSION...FOSTER  
AVIATION...TS  
MARINE...WROE  
 
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