664
FXHW60 PHFO 051350
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
350 AM HST WED AUG 5 2026
SYNOPSIS
LIGHT TO MODERATE TRADE WINDS WILL PREVAIL FOR THE NEXT FEW DAYS,
FOLLOWED BY INCREASING TRADE WIND SPEEDS THIS WEEKEND. MEANWHILE,
AN UPPER DISTURBANCE JUST TO THE NORTHWEST WILL ENHANCE SHOWERS
OVER THE WESTERN END OF THE STATE FOR THE NEXT FEW DAYS, AND COULD
PRODUCE A FEW THUNDERSTORMS IN THE NORTHWEST COASTAL WATERS AS
WELL. THE FOCUS FOR INCREASED SHOWERS WILL SHIFT TO THE EASTERN
END OF THE STATE THIS WEEKEND AS AN AREA OF TROPICAL MOISTURE
PASSES BY.
DISCUSSION
EARLY THIS MORNING, SCATTERED THUNDERSTORMS ARE OCCURRING JUST
OUTSIDE OF THE COASTAL WATERS WITHIN THE OFFSHORE ZONE ABOUT 60
MILES NORTHWEST OF KAUAI. THESE THUNDERSTORMS ARE BEING SUPPORTED
BY AN UPPER LOW AND ITS ASSOCIATED MID-LEVEL TROUGH NORTHWEST OF
THE MAIN HAWAIIAN ISLANDS. THE 12Z UPPER AIR SOUNDING AT LIHUE IS
SIMILAR TO THE PREVIOUS ONE FROM YESTERDAY AFTERNOON, DEPICTING AN
ERODED TRADE WIND INVERSION, SUFFICIENT CONVECTIVE AVAILABLE
POTENTIAL ENERGY (CAPE), AND AROUND 42 KT OF EFFECTIVE SHEAR, ALL
OF WHICH POINT TO AN UNSTABLE ENVIRONMENT OVER THE WESTERN END OF
THE STATE. ALTHOUGH THE THUNDERSTORM ACTIVITY HAS REMAINED TO THE
WEST THUS FAR IN CLOSER PROXIMITY TO THE UPPER DISTURBANCE,
VARIOUS CAMS SHOW THAT THUNDERSTORMS COULD CREEP INTO THE COASTAL
WATERS NEAR NIIHAU AND WATERS NORTH AND WEST OF KAUAI LATER THIS
MORNING AS THE COOLER 500MB TEMPERATURES EDGE CLOSER TO THE
ISLANDS. THEREFORE, ISOLATED THUNDER CHANCES HAVE BEEN INTRODUCED
FOR THESE AREAS WITH THIS MORNING'S FORECAST PACKAGE.
THE UPPER LOW AND MID-LEVEL THROUGH WILL LINGER FOR THE NEXT
COUPLE OF DAYS, ENHANCING INCOMING TRADE WIND SHOWERS ACROSS THE
WESTERN HALF OF THE STATE. THE UPPER LOW IS FORECAST TO LIFT AWAY
TO THE NORTH ON FRIDAY, RETURNING MORE STABLE CONDITIONS TO THE
AREA.
MEANWHILE, TRADE WINDS WILL REMAIN AT ONLY LIGHT TO MODERATE
SPEEDS FOR THE NEXT COUPLE OF DAYS AS THE REMNANTS OF FORMER
TROPICAL CYCLONE GENEVIEVE CUT OFF THE HIGH PRESSURE TO OUR NORTH,
INTERRUPTING THE TRADE WIND FLOW. THE WEAKER TRADES WILL LIKELY
RESULT IN LOCALIZED SEA BREEZES EACH DAY, BRINGING INCREASED
CLOUD BUILDUPS AND A FEW SHOWERS EACH AFTERNOON. SHOWERS WILL BE
MORE PROMINENT ACROSS KAUAI AND OAHU DUE TO MORE AVAILABLE
MOISTURE AND INSTABILITY. BY THE WEEKEND, TRADE WINDS WILL
INCREASE BACK TO LOCALLY BREEZY LEVELS.
THE FORECAST BECOMES MORE INTERESTING AGAIN THIS WEEKEND AS MODEL
GUIDANCE CONTINUES TO SUGGEST THAT A PLUME OF MOISTURE WILL EITHER
MOVE OVER OR VERY NEAR THE EASTERN END OF THE STATE LATE SATURDAY
INTO SUNDAY. DESPITE MOST GUIDANCE KEEPING THE BULK OF THE
MOISTURE JUST SOUTH OF THE ISLANDS, IT IS LIKELY THAT AT LEAST
SOME OF THE ENHANCED TROPICAL MOISTURE WILL BECOME EMBEDDED WITHIN
THE TRADE WIND FLOW, INCREASING SHOWERS FOR MAUI AND THE BIG
ISLAND. WITH THIS MORNING'S FORECAST UPDATES, RAIN CHANCES HAVE
BEEN ADJUSTED UPWARD TO BETTER HIGHLIGHT THE INCREASING POTENTIAL
FOR SHOWERS THIS WEEKEND OVER MAUI AND THE BIG ISLAND. THE FINER
DETAILS SHOULD BECOME MORE CLEAR OVER THE NEXT FEW DAYS.
AVIATION
A WEAK HIGH PRESSURE RIDGE FAR NORTH OF THE STATE WILL KEEP
GENTLE TRADE WINDS IN THE FORECAST. BRIEF PERIODS OF SHOWERS WILL
FAVOR WINDWARD MOUNTAIN SLOPES IN THE OVERNIGHT TO EARLY MORNING
HOURS. DURING THE DAY TIME A HYBRID TRADE WIND WITH SEA BREEZES
ALONG LEEWARD MOUNTAIN SLOPES WILL PRODUCE A FEW STRAY AFTERNOON
TO EARLY EVENING SHOWERS OVER SOUTH AND WEST SLOPES OF EACH
ISLAND.
AIRMET SIERRA IN EFFECT FOR MOUNTAIN OBSCURATION ABOVE 020 FOR THE
ENTIRE ISLAND OF KAUAI.
AIRMET TANGO MAY BE ISSUED LATER THIS MORNING DUE TO UPPER LEVEL
TURBULENCE AS AN UPPER LEVEL LOW AND ASSOCIATED SUBTROPICAL JET
STREAM APPROACHES KAUAI FROM THE NORTHWEST.
MARINE
A WEST TO EAST ORIENTED STATIONARY FRONT REMAINS ANCHORED WELL
NORTH OF THE STATE. THIS, ALONG WITH A SURFACE LOW FAR NORTHEAST
OF THE STATE WILL HELP TO LIMIT TRADE WIND SPEEDS ACROSS THE
ISLANDS TODAY. AS BOTH FEATURES DISSIPATE BY LATE THIS WEEK,
BUILDING HIGH PRESSURE NORTH OF THE ISLANDS WILL HELP STRENGTHEN
TRADE WINDS BACK TO FRESH TO LOCALLY BREEZY. SMALL CRAFT
ADVISORIES WILL BE NEEDED FOR AT LEAST THE TYPICAL WINDIER WATERS
FRIDAY THROUGH THIS WEEKEND.
ISOLATED THUNDERSTORMS WILL BE POSSIBLE TODAY OVER THE WATERS WEST
OF KAUAI AS AN UPPER LEVEL DISTURBANCE LINGERS WEST OF THE STATE.
SURF ALONG SOUTH-FACING SHORES WILL REMAIN BELOW SEASONAL AVERAGES
THROUGH LATE THIS WEEK. BY THIS WEEKEND, A SMALL, LONG PERIOD
SOUTH SWELL IS EXPECTED TO ARRIVE, FOLLOWED BY A SERIES OF
REINFORCING SOUTH SWELLS THAT WILL BOOST SURF HEIGHTS TO NEAR OR
ABOVE SEASONAL AVERAGES INTO NEXT WEEK.
SMALL, MEDIUM PERIOD EASTERLY SWELL GENERATED FROM FORMER TROPICAL
CYCLONE GENEVIEVE CONTINUES TO LINGER, BUT WILL GRADUALLY EASE
TODAY. CHOPPY CONDITIONS WILL REMAIN, GENERATED BY THE MODERATE
TRADE WINDS.
SURF ALONG NORTH FACING AND WEST SHORES WILL REMAIN FLAT TO TINY
THROUGH THE FORECAST PERIOD, EXCEPT FOR AREAS EXPOSED TO THE EASTERLY
TRADE WRAP.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...VAUGHAN
AVIATION...BOHLIN
MARINE...THOMAS
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