034
FXHW60 PHFO 010128
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
328 PM HST SAT MAY 31 2025
SYNOPSIS
MODERATE TO BREEZY EASTERLY TRADE WINDS WILL BRIEFLY SHIFT OUT OF
THE EAST-SOUTHEAST TONIGHT THROUGH MONDAY AS A BROAD SURFACE
TROUGH DEVELOPS FAR NORTHWEST OF THE ISLANDS. INCREASING MOISTURE
AND INSTABILITY 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
MODERATE TO BREEZY TRADES WILL VEER EAST-SOUTHEAST TONIGHT
THROUGH MONDAY AS A STRENGTHENING HIGH WELL TO OUR NORTHEAST
INTERACTS WITH A BROAD TROUGH APPROACHING FROM THE NORTHWEST. THIS
SLIGHTLY VEERED WIND DIRECTION WILL DISRUPT THE TRADE WIND FLOW
ACROSS THE SMALLER ISLANDS AND ALLOW FOR THE DEVELOPMENT OF LAND
AND SEA BREEZES ACROSS LEEWARD AREAS. AN UPPER-LEVEL TROUGH
APPROACHING FROM THE NORTHWEST WILL LOWER 500 MB HEIGHTS AND
TEMPERATURES, INTRODUCING SOME INSTABILITY OVER THE WESTERN HALF
OF THE STATE SUNDAY THROUGH EARLY NEXT WEEK. THE INSTABILITY
ASSOCIATED WITH THIS FEATURE AND AN INFLUX OF LOW LEVEL MOISTURE
MAY HELP TO ENHANCE WINDWARD SHOWERS OVERNIGHT AND SEA BREEZE-
INDUCED CLOUDS AND SHOWERS OVER LEEWARD AREAS DURING THE
AFTERNOONS, PARTICULARLY OVER THE WESTERN HALF OF THE STATE. THIS
EAST-SOUTHEASTERLY FLOW MAY ALSO TRANSPORT VOG TO A MAJORITY OF
THE ISLAND CHAIN THROUGH EARLY NEXT WEEK.
A RETURN TO BREEZY AND MORE STABLE TRADE WIND CONDITIONS IS
EXPECTED BY MONDAY NIGHT AS UPPER-LEVEL HEIGHTS RISE, DRIER AIR
FILTERS IN FROM THE EAST, AND THE SURFACE TROUGH WEAKENS AND
MOVES AWAY FROM THE STATE. THIS WILL RESULT IN A MORE TYPICAL
EASTERLY TRADE WIND PATTERN THROUGH THURSDAY, WITH SHOWERS
FAVORING WINDWARD AND MAUKA AREAS AND GENERALLY DRY CONDITIONS
PREVAILING ELSEWHERE.
FOR THE LATTER END OF THE WEEK AND INTO THE WEEKEND, A WEAK
UPPER-LEVEL TROUGH WILL MOVE OVERHEAD, INTRODUCING SOME MORE
INSTABILITY TO THE REGION. HOWEVER, THE INSTABILITY AND AVAILABLE
MOISTURE LOOK RATHER UNIMPRESSIVE, SO NOT EXPECTING MUCH MORE THAN
PERHAPS A SLIGHT ENHANCEMENT OF TRADE WIND SHOWERS FOR THE END OF
THE FORECAST PERIOD AT THIS TIME.
AVIATION
AIRMET TANGO IN EFFECT FOR TEMPO MODERATE TURBULENCE BELOW 7000
FEET SOUTH THROUGH WEST OF MOUNTAINS DUE TO BREEZY TRADE WINDS.
THE WINDS WILL MAINTAIN STRENGTH INTO SUNDAY, BUT VEER
SOUTHEASTERLY AND PARTIALLY BLOCK SOME LEEWARD AREAS FROM THE FULL
STRENGTH OF THE WINDS, AND MOVING THE MAIN TURBULENCE AREA TO THE
NORTHWEST SECTOR OF THE ISLANDS. LLWS POSSIBLE THROUGH THE REST OF
THIS AFTERNOON AND SUNDAY AFTERNOON AT NEAR PHOG TERMINAL.
LOW CLOUDS AND SHOWERS MAY FILL IN A BIT OVERNIGHT WITH POSSIBLE
MVFR CEILINGS AND VISIBILITY ACROSS ALL WINDWARD AREAS.
MARINE
MODERATE TO LOCALLY STRONG TRADE WINDS WILL VEER OUT OF THE EAST
TO EAST-SOUTHEAST LATE TONIGHT AND SUNDAY AS THE SUBTROPICAL
RIDGE IS PUSHED CLOSER TO THE ISLANDS BY A DEVELOPING TROUGH
NORTHWEST OF KAUAI. THE SMALL CRAFT ADVISORY (SCA) HAS BEEN
ADJUSTED SLIGHTLY FROM THE TYPICALLY WINDY WATERS AROUND THE BIG
ISLAND AND MAUI TO ACCOUNT FOR ENHANCED WINDS NORTH OF THESE
ISLANDS. ON MONDAY, THE TROUGH WILL MOVE WESTWARD, AND THE SURFACE
RIDGE TO THE NORTH WILL REBUILD, CAUSING TRADE WINDS TO SHIFT
BACK TO A MORE EASTERLY DIRECTION. THE SCA WILL LIKELY BE
RECONFIGURED TO THE TYPICALLY WINDY WATERS BY MONDAY AND SHOULD
REMAIN IN PLACE THROUGH AT LEAST MIDWEEK.
A LATE SEASON NORTHWEST SWELL IS PEAKING THIS AFTERNOON, BRINGING
SURF WELL ABOVE SEASONAL AVERAGE. NEARSHORE PACIOOS BUOYS AT
HANALEI AND WAIMEA BAY SHOWED THE 320-330 DEGREE SWELL AT 6 TO 7
FEET AT 13 TO 14 SECONDS, PRODUCING SURF JUST BELOW HIGH SURF
ADVISORY LEVELS. THE SWELL WILL DECLINE TONIGHT AND SUNDAY, WITH
NORTH SHORE SURF DROPPING TO NEAR JUNE AVERAGE FOR THE FIRST HALF
OF THE WORK WEEK. TINY SURF IS EXPECTED BY THURSDAY.
SURF ALONG SOUTH-FACING SHORES WILL CONTINUE TO SEE A MIX OF SMALL
BACKGROUND SWELL FOR THE NEXT FEW DAYS, FOLLOWED BY A SMALL
INCONSISTENT SOUTHWEST SWELL LATE TUESDAY AND WEDNESDAY. A STORM
LOW MOVED INTO THE HAWAII SWELL WINDOW SOUTHEAST OF NEW ZEALAND
YESTERDAY AND IS GENERATING SEAS IN EXCESS OF 30 FEET TODAY. THE
RESULTING LONG-PERIOD SOUTH-SOUTHWEST SWELL WILL BUILD ON FRIDAY
AND PEAK NEXT WEEKEND, LEADING TO SURF WELL ABOVE JUNE AVERAGE.
SURF ALONG EAST-FACING SHORES WILL REMAIN SMALL AND CHOPPY THROUGH
SUNDAY, THEN GRADUALLY BUILD TO NEAR OR ABOVE SEASONAL AVERAGE
MONDAY THROUGH WEDNESDAY DUE TO A RETURN OF FRESH TO STRONG
TRADES OVER AND UPSTREAM OF THE ISLANDS.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR MAUI COUNTY
WINDWARD WATERS-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND
WINDWARD WATERS-BIG ISLAND LEEWARD WATERS.
DISCUSSION...FARRIS
AVIATION...FOSTER
MARINE...WROE
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