177
FXHW60 PHFO 311314
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
314 AM HST SAT MAY 31 2025
SYNOPSIS
BREEZY EASTERLY TRADE WINDS WILL PERSIST TODAY, WITH SHOWERS
FAVORING WINDWARD AND MAUKA AREAS. THE TRADES WILL BRIEFLY WEAKEN
AND SHIFT OUT OF THE EAST-SOUTHEAST TONIGHT THROUGH SUNDAY AS A
BROAD SURFACE TROUGH DEVELOPS FAR NORTHWEST OF THE ISLANDS.
INCREASING MOISTURE MAY LEAD TO ENHANCED SHOWER ACTIVITY SUNDAY
INTO MONDAY, PARTICULARLY OVER THE WESTERN END OF THE STATE.
BREEZY EASTERLY TRADES AND DRIER CONDITIONS ARE EXPECTED TO RETURN
DURING THE FIRST HALF OF NEXT WEEK AS THE TROUGH WEAKENS AND
SHIFTS AWAY FROM THE REGION.
DISCUSSION
A WET AND BREEZY TRADE WIND PATTERN REMAINS IN PLACE THIS
MORNING, WITH NUMEROUS SHOWERS FAVORING WINDWARD AND MAUKA AREAS.
SOME OF THESE SHOWERS ARE MANAGING TO REACH THE TYPICALLY DRIER
LEEWARD AREAS OVER THE SMALLER ISLANDS, DUE TO A WEAK MID-LEVEL
TROUGH, AN ELEVATED TRADE WIND INVERSION POSITIONED BETWEEN 8,000
AND 9,000 FT, AND POCKETS OF MOISTURE MOVING THROUGH. PEAK
OVERNIGHT RAINFALL ACCUMULATIONS AROUND THE STATE RANGED FROM A
QUARTER TO JUST UNDER HALF OF AN INCH (THROUGH 2 AM HST). THIS
SHOWERY PATTERN IS EXPECTED TO PERSIST THROUGH THE MORNING,
GRADUALLY IMPROVING LATER IN THE DAY AS THE MOISTURE SHIFTS
WESTWARD.
UPPER-LEVEL HEIGHT FALLS AND THE DEVELOPMENT OF A BROAD SURFACE
TROUGH FAR NORTHWEST OF THE STATE WILL LEAD TO A WEAKENING AND
VEERING OF THE TRADES OUT OF THE EAST-SOUTHEAST LATE TONIGHT
THROUGH THE SECOND HALF OF THE WEEKEND. THIS EVOLVING PATTERN WILL
DRAW INCREASED MOISTURE NORTHWARD INTO THE AREA, ENHANCING
INSTABILITY AND SUPPORTING GREATER CLOUD AND SHOWER COVERAGE -
PARTICULARLY OVER THE WESTERN END OF THE STATE, WHERE THE
INSTABILITY WILL BE MORE PRONOUNCED. AS WINDS EASE ON SUNDAY,
SHOWERS WILL BECOME MORE FOCUSED OVER INTERIOR AND LEEWARD AREAS
OF KAUAI AND OAHU DURING THE AFTERNOON, WITH A FEW POTENTIALLY
BECOMING BRIEFLY HEAVY. THIS UNSETTLED PATTERN WILL PERSIST INTO
SUNDAY NIGHT AND EARLY MONDAY, WITH LAND BREEZES DEVELOPING ACROSS
THE WESTERN ISLANDS AND SHOWERS FAVORING WINDWARD AND COASTAL
LOCATIONS - AGAIN WITH THE POTENTIAL FOR LOCALLY HEAVY DOWNPOURS.
MEANWHILE, MORE STABLE CONDITIONS AND A CONTINUATION OF TYPICAL
EASTERLY TRADES ARE EXPECTED TO HOLD ACROSS THE EASTERN END OF THE
STATE.
A RETURN TO BREEZY AND MORE STABLE TRADE WIND CONDITIONS IS
EXPECTED BY MONDAY NIGHT INTO THE FIRST HALF OF NEXT WEEK AS
UPPER-LEVEL HEIGHTS RISE AND DRIER AIR FILTERS IN FROM THE EAST.
THIS WILL RESULT IN A MORE TYPICAL TRADE WIND PATTERN, WITH
SHOWERS FAVORING WINDWARD AND MAUKA AREAS AND GENERALLY DRY
CONDITIONS PREVAILING ELSEWHERE.
AVIATION
BREEZY TRADES WILL PERSIST TODAY, THEN WEAKEN AND VEER OUT OF THE
SOUTHEAST LATER TONIGHT THROUGH SUNDAY. LOW CIGS AND SHRA SHOULD
IMPACT WINDWARD AND MAUKA LOCATIONS, WITH SOME SPILLOVER TO
LEEWARD SIDES. MVFR CONDITIONS CAN BE EXPECTED IN HEAVIER SHRA,
WITH VFR CONDITIONS PREVAILING OTHERWISE.
AIRMET SIERRA IS IN EFFECT FOR MTN OBSC FOR N THRU SE SECTIONS OF
ALL ISLANDS.
AIRMET TANGO IS IN EFFECT FOR MOD TURB OF ALL ISLANDS DOWNWIND OF
ISLAND TERRAIN.
MARINE
FRESH TO STRONG EASTERLY TRADES ASSOCIATED WITH A SURFACE RIDGE
TO THE NORTH WILL CONTINUE TODAY, WITH THE STRONGEST WINDS OVER
THE TYPICALLY WINDIER CHANNELS AND WATERS AROUND MAUI COUNTY AND
THE BIG ISLAND. FORECAST GUIDANCE SUGGESTS THE RIDGE WILL BRIEFLY
WEAKEN THROUGH THE LATTER HALF OF THE WEEKEND AND AS A BROAD
SURFACE TROUGH DEVELOPS FAR NORTHWEST OF THE AREA. THIS WILL LEAD
TO THE TRADES VEERING OUT OF THE EAST-SOUTHEAST TO SOUTHEAST BY
SUNDAY, WITH LIGHTER AND MORE SOUTHEAST WINDS OVER THE WESTERN END
OF THE STATE AND FRESH EAST-SOUTHEAST WINDS CONTINUING OVER THE
EASTERN END. THE WINDS WILL SHIFT BACK OUT OF THE EAST AND
STRENGTHEN EARLY NEXT WEEK AS THE TROUGH WEAKENS AND TRACKS AWAY
FROM THE AREA.
SURF ALONG EXPOSED NORTH AND WEST-FACING SHORES WILL CLIMB WELL
ABOVE AVERAGE FOR THIS TIME OF YEAR TODAY AS A FRESH, MEDIUM-
PERIOD NORTH-NORTHWEST (330-340 DEGREES) SWELL BUILDS DOWN THE
ISLAND CHAIN. SWELL OBSERVATIONS AT THE OFFSHORE BUOYS SURGED
ABOVE PREDICTED LEVELS OVERNIGHT, WHICH WILL LEAD TO SURF HEIGHTS
NEARING ADVISORY LEVELS TODAY AS IT FILLS IN. THIS NORTH-
NORTHWEST SOURCE WILL PEAK TODAY, THEN STEADILY LOWER LATE
TONIGHT THROUGH EARLY NEXT WEEK, WITH HEIGHTS RETURNING TO
SEASONAL LEVELS.
SURF ALONG EXPOSED SOUTH-FACING SHORES WILL CONTINUE TO SEE A MIX
OF LONG-PERIOD BACKGROUND SOUTH-SOUTHWEST AND SHORTER-PERIOD
SOUTHEAST SWELL THROUGH THE MIDDLE OF NEXT WEEK. ANOTHER LONG-
PERIOD SOUTH-SOUTHWEST SWELL IS POSSIBLE LATE NEXT WEEK DUE TO A
SYSTEM PASSING THROUGH OUR SWELL WINDOW NEAR NEW ZEALAND. IF THIS
MATERIALIZES, SURF COULD CLIMB TO ABOVE AVERAGE LEVELS BY NEXT
WEEKEND.
SURF ALONG EAST-FACING SHORES WILL REMAIN SMALL AND CHOPPY THROUGH
THE WEEKEND, THEN GRADUALLY BUILD THROUGH THE UPCOMING WEEK DUE
TO A RETURN OF FRESH TO STRONG TRADES LOCALLY AND UPSTREAM ACROSS
THE NORTHEASTERN PACIFIC.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...GIBBS
AVIATION...WALSH
MARINE...GIBBS
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