044
FXHW60 PHFO 161336
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
336 AM HST SAT MAY 16 2026
SYNOPSIS
A SLIGHTLY UNSTABLE TRADE WIND FLOW WILL PREVAIL TODAY AS A
WEAKENING UPPER LEVEL LOW PRODUCES ISOLATED HEAVY SHOWERS AND
THUNDERSTORMS, MAINLY ON THE BIG ISLAND. SOMEWHAT WET EASTERLY
TRADE WINDS WILL FOCUS MOST RAINFALL ALONG WINDWARD SLOPES SUNDAY
INTO EARLY NEXT WEEK. A MORE STABLE, MODERATE TO BREEZY TRADE WIND
FLOW WILL DEVELOP TUESDAY AND WEDNESDAY.
DISCUSSION
HEAVY SHOWERS AND THUNDERSTORMS DECREASED DRAMATICALLY YESTERDAY
EVENING AS THE UPPER LEVEL LOW OVER THE ISLANDS WEAKENED, AND
EASTERLY TRADE WINDS HAVE FOCUSED MAINLY MODERATE SHOWERS OVER
WINDWARD SLOPES OVERNIGHT. THERE IS SOME LINGERING INSTABILITY
FROM THE UPPER LOW, BUT SO FAR, ONLY A FEW HEAVY SHOWERS HAVE
BRIEFLY FLARED UP, EVEN WITH A STEADY SUPPLY OF LOW LEVEL MOISTURE
STREAMING INTO WINDWARD BIG ISLAND. GIVEN RECENT TRENDS, THE FLOOD
WATCH HAS BEEN CANCELLED.
CHANCES OF HEAVY SHOWERS AND THUNDERSTORMS WILL DIMINISH TODAY AS
THE UPPER LOW DRIFTS EASTWARD AND WEAKENS. MODERATE EASTERLY
TRADE WINDS WILL FOCUS RAINFALL OVER WINDWARD AREAS OF ALL
ISLANDS, WITH MORE SHOWER ACTIVITY EXPECTED ON BIG ISLAND DUE TO
INCREASED LOW LEVEL MOISTURE FILTERING IN FROM THE EAST.
LINGERING INSTABILITY FROM THE DEPARTING UPPER LEVEL LOW COULD
ALSO TRIGGER ISOLATED HEAVY SHOWERS AND THUNDERSTORMS ON THE BIG
ISLAND, BUT THE THREAT OF FLOODING DOES NOT APPEAR HIGH ENOUGH TO
CONTINUE THE FLOOD WATCH TODAY.
MODERATE EASTERLY WINDS AND A SOMEWHAT WET PATTERN OF MAINLY
WINDWARD AND MAUKA SHOWERS IS EXPECTED SUNDAY INTO EARLY TUESDAY.
THE UPPER LOW WILL BE REPLACED BY A BROAD AND FLAT UPPER TROUGH,
WHICH WILL NOT ALLOW THE ATMOSPHERE TO BECOME VERY STABLE. AS A
RESULT, WE CANNOT RULE OUT A BRIEFLY HEAVY SHOWER, MAINLY OVER THE
HEATED LEEWARD SLOPES OF THE BIG ISLAND AND MAUI DURING THE
AFTERNOON HOURS.
INCREASED STABILITY AND STRONGER TRADE WINDS ARE DUE LATE TUESDAY
OR WEDNESDAY. EXPECT A TYPICAL PATTERN OF MAINLY WINDWARD RAINFALL
AND MOSTLY DRY CONDITIONS LEEWARD.
AVIATION
AN UPPER LEVEL LOW CONTINUES TO WEAKEN THIS MORNING JUST NORTH OF
THE BIG ISLAND. EXPECT AN UNSETTLED TRADE WIND WEATHER PATTERN
WITH BRIEF PERIODS OF MVFR CONDITIONS. SHOWER TRENDS WILL DECREASE
THROUGH THE WEEKEND AS THE UPPER LOW CONTINUES TO WEAKEN AND
MARCH EASTWARD.
AIRMET SIERRA REMAINS IN EFFECT FOR MOUNTAIN OBSCURATION OVER
KAUAI, OAHU, MOLOKAI, AND BIG ISLAND.
MARINE
WINDS WILL REMAIN SLIGHTLY EAST SOUTHEASTERLY THIS WEEKEND AT
MODERATE TO FRESH LEVELS. THE UPPER LEVEL DISTURBANCE THAT GAVE US
SOME SEVERE WEATHER YESTERDAY WILL BE MOVING NORTHEAST AWAY FROM
THE STATE, WITH STABILITY SLOWLY RETURNING TO THE REGION. AS A
RESULT, EXPECT DECREASING SHOWERS AND THUNDERSTORMS ACROSS THE
WATERS. A MORE TYPICAL EASTERLY TRADE WIND PATTERN WILL RETURN
NEXT WEEK.
A SMALL, MEDIUM PERIOD NORTH NORTHWEST (320-330 DEGREE) SWELL
THAT PEAKED OVERNIGHT WILL CONTINUE TO DECLINE. SURF ALONG NORTH
AND WEST FACING SHORES WILL FOLLOW SUIT, EASING DURING THE
WEEKEND.
A MIX OF SMALL, MEDIUM TO LONG PERIOD SOUTH SWELLS WILL MAINTAIN
SMALL SURF ALONG SOUTH-FACING SHORES THIS WEEKEND. A SERIES OF
GALE LOWS PASSING SOUTH OF NEW ZEALAND SHOULD SEND SMALL SOUTH
SWELL ENERGY INTO THE SOUTHERN WATERS THROUGH NEXT WEEK. SURF
SHOULD LIFT TO SUMMER AVERAGES AROUND SUNDAY AND HOLD THROUGH
WEDNESDAY. MODERATE TO FRESH TRADES WILL MAINTAIN ROUGH AND
CHOPPY SURF ALONG EAST-FACING SHORES.
TIDES WILL PEAK AROUND 2.5 TO 3.0 FT MLLW THIS WEEKEND. MINOR
OVERWASH OF LOW LYING COASTAL AREAS WILL BE POSSIBLE DURING TIMES
OF HIGH TIDE.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...WROE
AVIATION...BOHLIN
MARINE...WALSH
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