086
FXHW60 PHFO 051838
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
838 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 COUPLE OF DAYS, AND
COULD PRODUCE A FEW THUNDERSTORMS IN THE WESTERN 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
WATER VAPOR IMAGERY SHOWS AN UPPER LOW WEST OF THE MAIN HAWAIIAN
ISLANDS THIS MORNING. THIS FEATURE IS GENERATING INSTABILITY AND
WIND SHEAR RESULTING IN SCATTERED THUNDERSTORMS AROUND 50 MILES
WEST OF NIIHAU. GUIDANCE KEEPS THE ACTIVITY OVER THE COASTAL
WATERS JUST WEST OF THE ISLANDS TODAY AND THURSDAY, WHICH THE
CURRENT FORECAST DEPICTS. HOWEVER, ENHANCED SHOWERS ARE EXPECTED
TODAY ACROSS KAUAI (AND OAHU TO A LESSER EXTENT) AS THE
INSTABILITY CREEPS ONTO THE WESTERN END 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 HAVE CUT OFF THE HIGH PRESSURE TO OUR
NORTH, INTERRUPTING THE TRADE WIND FLOW. THE WEAKER TRADES WILL
LIKELY RESULT IN LOCALIZED SEA BREEZES EACH AFTERNOON, 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 STATE, 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.
AVIATION
A WEAK HIGH PRESSURE RIDGE FAR NORTH OF THE STATE WILL MAINTAIN GENTLE
TRADE WINDS IN THE FORECAST. OVERALL, A FAIRLY DRY DAY IS EXPECTED
DURING THE DAY TODAY BUT A FEW SHOWERS WILL BE POSSIBLE ESPECIALLY
OVER AND AROUND KAUAI. DUE TO THE GENTLE TRADE WINDS, SEA BREEZES
COULD DEVELOP LATER THIS MORNING, WHICH WOULD ALLOW FOR AFTERNOON
CLOUDS AND A FEW SHOWERS OVER SELECT LEEWARD SLOPES.
AN UPPER LEVEL DISTURBANCE IS PRODUCING SCATTERED THUNDERSTORMS
JUST WEST OF KAUAI THIS MORNING. SIGMET XRAY IS IN EFFECT FOR THE
POTENTIAL OF SEVERE TURBULENCE ASSOCIATED WITH THESE
THUNDERSTORMS. THE THREAT FOR THUNDERSTORMS SHOULD STAY WEST OF
KAUAI AND IS EXPECTED TO DISSIPATE BY THIS AFTERNOON.
AIRMET SIERRA IN EFFECT FOR MOUNTAIN OBSCURATION ABOVE 020 FOR THE
ENTIRE ISLAND OF KAUAI. THIS AIRMET WILL LIKELY BE CANCELLED LATER
THIS MORNING.
MARINE
MODERATE TRADES PERSIST AS SURFACE TROUGHING TO THE NE MAINTAINS A
RATHER WEAK PRESSURE GRADIENT OVER THE STATE. DISSIPATION OF THE
TROUGH TO THE NE COMBINED WITH RENEWED TROUGH DEVELOPMENT S OF THE
ISLANDS WILL FAVOR BREEZY TRADES BY WEEK'S END. THE RESIDENT UPPER
LEVEL LOW IS SUPPORTING ONGOING ISOLATED THUNDERSTORMS NW OF
KAUAI IN THE VICINITY OF THE NEARSHORE WATERS THIS MORNING. THIS
ACTIVITY IS FORECAST TO DIMINISH THROUGH THE DAY.
SURF ALONG S SHORES REMAINS BELOW THE SEASONAL AVERAGE. BY THIS
WEEKEND A SMALL, LONG PERIOD S SWELL ARRIVES FOLLOWED BY A SERIES
OF REINFORCING SWELLS THAT WILL BOOST SURF TOWARD SEASONAL
AVERAGES HEADING INTO NEXT WEEK.
SMALL, MEDIUM PERIOD E SWELL GENERATED FROM FORMER TROPICAL
CYCLONE GENEVIEVE LINGERS, BUT WILL EASE THROUGH TODAY. MODERATE
TRADES MAINTAIN SHORT PERIOD CHOP.
SURF ALONG N AND W SHORES REMAINS FLAT TO TINY THROUGH THE PERIOD
EXCEPT FOR LOCALES EXPOSED TO TRADE WIND SWELL
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...FOSTER
AVIATION...KINO
MARINE...JVC
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