940
FXHW60 PHFO 070108 CCA
AFDHFO
AREA FORECAST DISCUSSION...CORRECTED
NATIONAL WEATHER SERVICE HONOLULU HI
308 PM HST THU AUG 6 2026
SYNOPSIS
MODERATE TRADE WINDS WILL PREVAIL THROUGH TONIGHT, THEN INCREASE
FRIDAY THROUGH THIS WEEKEND. MOST SHOWER ACTIVITY WILL OCCUR
DURING THE NIGHTS AND EARLY MORNINGS AND AFFECT WINDWARD AND MAUKA
LOCATIONS. FROM SATURDAY AFTERNOON THROUGH MONDAY, AN AREA OF
TROPICAL MOISTURE WILL MOVE OVER THE SOUTHERN HALF OF THE STATE
(BIG ISLAND AND MAUI) FROM EAST TO WEST AND BRING ENHANCED SHOWERS.
A TYPICAL STABLE TRADE WIND PATTERN WILL RETURN BY TUESDAY OF
NEXT WEEK.
DISCUSSION
AN UPPER LEVEL LOW TO THE WEST-NORTHWEST IS CURRENTLY BRINGING
HIGH CLOUDS OVER THE STATE, WHILE A WEAK SURFACE TROUGH TO THE
NORTHEAST HAS SUPPRESSED TRADE WIND SPEEDS. BOTH THE UPPER LOW TO
THE WEST AND TROUGH TO THE NORTHEAST WILL MOVE NORTH AND TRADE
WINDS WILL STRENGTHEN INTO THE MODERATE TO BREEZY RANGE FRIDAY
INTO THE WEEKEND. SHOWERS WILL FOCUS MOSTLY OVER WINDWARD AND
MOUNTAIN AREAS AND SHOULD STAY ON THE LIGHTER SIDE DUE TO A NORMAL
SUMMERTIME INVERSION HEIGHT OF APPROXIMATELY 6,000 FT.
CURRENT SATELLITE IMAGERY DEPICTS A TROPICAL LOW WITH AN
ASSOCIATED TROPICAL WAVE APPROXIMATELY 960 NM EASE-SOUTHEAST OF
HILO. THIS TROPICAL FEATURE APPEARS TO BE SEPARATING FROM THE
ITCZ AND MODEL GUIDANCE PROJECTS THIS LOW WEAKENING TO A TROUGH
OVER THE NEXT FEW DAYS AS IT MOVES WEST-NORTHWEST. THIS TROUGH
WILL HAVE A DECENT MOISTURE PROFILE ASSOCIATED WITH IT WHEN IT
ARRIVES AND IT IS FORECAST TO REACH THE BIG ISLAND BY SATURDAY
EVENING. RAINFALL CHANCES AND HUMIDITY WILL INCREASE FOR THE BIG
ISLAND AND MAUI COUNTY, THEN TO A LESSER EXTEND, OAHU AND KAUAI
SUNDAY INTO MONDAY. THE MOST RECENT GFS MODEL TIME- HEIGHT CROSS
SECTION DEPICTS THE BOUNDARY LAYER INVERSION WEAKENING, AS
CONDITIONS BECOME MORE UNSTABLE, AND MOISTURE DEEPENING UP TO
15000-20000 FEET. THUS, FROM SATURDAY AFTERNOON THROUGH MONDAY,
EMBEDDED POCKETS OF HEAVIER RAINFALL WILL BE POSSIBLE FOR THE BIG
ISLAND AND MAUI COUNTY, ESPECIALLY FOR WINDWARD LOCATIONS. WHILE
STILL TOO EARLY TO DETERMINE MORE CONCRETE FORECAST DETAILS, A FEW
INCHES OF RAINFALL ACCUMULATION COULD FALL ON SOME OF THE WETTEST
WINDWARD SITES.
TYPICAL MODERATE TRADE WIND WEATHER WILL RETURN BY TUESDAY
THROUGH THE END OF THE WEEK WITH SCATTERED SHOWERS MAINLY
WINDWARD AND MAUKA AREAS DURING THE NIGHTS AND EARLY MORNINGS.
AVIATION
MODERATE TRADE WINDS STRENGTHEN TO BREEZY FRIDAY. ISOLATED
SHOWERS ARE POSSIBLE TONIGHT MAINLY WINDWARD AND MOUNTAIN AREAS.
ACROSS WINDWARD BIG ISLAND, INCREASING SHOWERS ARE ALSO POSSIBLE
FRIDAY DURING THE DAY WHICH COULD CREATE INTERMITTENT MVFR
CONDITIONS.
NO AIRMETS ARE IN EFFECT.
MARINE
MODERATE TRADES PERSIST AS SURFACE TROUGHING TO THE NORTHEAST
MAINTAINS A RATHER WEAK PRESSURE GRADIENT OVER THE STATE.
DISSIPATION OF THE TROUGH TO THE NORTHEAST COMBINED WITH RENEWED
TROUGH DEVELOPMENT SOUTH OF THE ISLANDS AND STRENGTHENING HIGH
PRESSURE TO THE NORTHEAST WILL FAVOR FRESH TO LOCALLY STRONG
TRADES BY WEEK'S END.
BACKGROUND MEDIUM AND LONG PERIOD ENERGY WILL PRODUCE SMALL SURF FOR
SOUTH FACING SHORES THROUGH FRIDAY. A SERIES OF LARGER, MEDIUM TO
LONG PERIOD SOUTH SWELLS ARRIVE BEGINNING ON SATURDAY, CAUSING SURF TO
TREND UP FOR SOUTH AND WEST FACING SHORES THIS WEEKEND INTO EARLY
NEXT WEEK. A MODERATE, LONG PERIOD SOUTH SWELL WILL PEAK NEAR THE
HIGH SURF ADVISORY THRESHOLD BY THE MIDDLE OF NEXT WEEK.
ALONG EAST FACING SHORES, TRADE WIND SWELL AND MODERATE TRADES
WILL SUPPORT SURF SLIGHTLY BELOW SEASONAL AVERAGES. SURF WILL BUILD
THIS WEEKEND IN RESPONSE TO STRENGTHENING TRADE WINDS. SURF ALONG
NORTH SHORES REMAINS FLAT TO TINY THROUGH THE PERIOD.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...TSAMOUS
AVIATION...PECHACEK/FARRIS
MARINE...JVC
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