414
FXHW60 PHFO 070619
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
819 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.
SHORT TERM UPDATE
WATER VAPOR IMAGERY LOOP FROM THIS EVENING DEPICTS THE BROAD
CYCLONIC SPIN OF AN UPPER LOW, CENTERED AROUND 450 MILES NORTHWEST
OF KAUAI. THIS FEATURE CONTINUES TO DRAW AREAS OF MID AND UPPER
LEVEL MOISTURE NORTHWARD OVER THE STATE.
TRADES HAVE REMAINED IN THE LIGHT TO MODERATE RANGE, THANKS TO A
TROUGH FAR TO THE NORTHEAST ACTING TO SUBDUE THE EFFECT OF
STRONGER HIGH PRESSURE FURTHER NORTH. THE 00Z HILO UPPER AIR
SOUNDING INDICATES A RATHER SHALLOW MARINE LAYER, NEAR 5000 FEET.
THIS HAS HELPED TO PUT UP A CAP ON ANY CUMULUS AND KEPT SHOWER
COVERAGE TO A MINIMUM. EXPECTING ONLY ISOLATED SHOWERS TO AFFECT
WINDWARD AND MAUKA TO CONTINUE TONIGHT. IN THE SHORT TERM UPDATE,
CHANCES OF PRECIPITATION AND CLOUD COVER WERE DECREASED ACROSS
ALL ISLANDS THROUGH FRIDAY MORNING TO ACCOUNT FOR CURRENT TRENDS.
ALL OTHER FORECAST PARAMETERS LOOKED ON TRACK.
AVIATION
TRADE WINDS ARE FORECAST TO RAMP UP INTO THE WEEKEND AS THE
DRIVING HIGH STRENGTHENS AND PUSHES SLIGHTLY CLOSER TO HAWAII.
STABILITY WILL ALSO BE INCREASING ON FRIDAY AS AN UPPER LOW TO THE
WEST LIFTS AWAY. LEEWARD TURBULENCE WILL LIKELY INCREASE AROUND
FRIDAY NIGHT OR SATURDAY, BUT NO AIRMET WILL BE NEEDED FOR NOW.
A BAND OF LOW CLOUDS AND SHOWERS WILL MOVE ONTO WINDWARD BIG
ISLAND TONIGHT, THEN BECOME MORE DIFFUSE AS IT SPREADS WESTWARD.
MOUNTAIN OBSCURATIONS/AIRMET SIERRA WILL BE POSSIBLE FOR THIS AREA
OVERNIGHT AS THIS MOISTURE TRACKS IN, BUT NOTHING WILL BE NEEDED
THROUGH THE EVENING.
MARINE
ISSUED AT 308 PM HST THU AUG 6 2026
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...FOSTER
MARINE...JVC
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