121
FXHW60 PHFO 141347
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
347 AM HST SUN JUN 14 2026
SYNOPSIS
SURFACE HIGH PRESSURE STRENGTHENS TO THE NORTHEAST OF THE STATE
TODAY AND WILL BRING AN INCREASE IN TRADE WIND FLOW. IN ADDITION,
EXPECT AN UPTICK IN LOW CLOUD COVER AND SHOWER ACTIVITY THROUGH
EARLY MONDAY OVER WINDWARD PORTIONS OF MAUI, MOLOKAI, AND OAHU AS
AN AREA OF ENHANCED MOISTURE MOVES IN FROM THE EAST. FROM LATE
MONDAY THROUGH FRIDAY, LIGHT EASTERLY WINDS WILL RETURN TO THE
REGION. AFTERNOON COASTAL SEA BREEZES SHOULD HELP TO FOCUS
SCATTERED CLOUDS AND ISOLATED SHOWERS OVER MAINLY INTERIOR AND
MOUNTAINOUS LOCATIONS. FOR THE LATTER PART OF THE WEEK, DEEPER
MOISTURE MOVING IN FROM THE SOUTHEAST COULD BRING INCREASED
PRECIPITATION CHANCES TO THE BIG ISLAND.
DISCUSSION
LATEST RADAR AND IR SATELLITE IMAGERY LOOP FROM THIS MORNING
SHOWED A BAND OF ENHANCED LOW CLOUDS AND SHOWERS MOVING INTO MAUI
COUNTY FROM THE EAST. FOR THE MOST PART, THIS ACTIVITY HAS BEEN
LIGHT, THOUGH SOME BRIEF POCKETS OF HEAVIER SHOWERS HAVE BEEN
NOTED. A FEW STATIONS ON THE WEST MAUI MOUNTAINS PICKED UP
JUST OVER HALF AN INCH OF RAINFALL ACCUMULATION OVER THE PAST 6
HOURS, BUT MOST WINDWARD SITES REPORTED LESS THAN A QUARTER INCH.
THROUGH THE REMAINDER OF THIS MORNING, SURFACE HIGH PRESSURE WILL
GRADUALLY BUILD WELL NORTHEAST OF THE STATE AND ALLOW TRADE WINDS
TO STRENGTHEN INTO THE MODERATE RANGE. BY THIS AFTERNOON, THESE
TRADES SHOULD HELP TO DRIVE THE AFOREMENTIONED AREA OF ENHANCED
LOW CLOUDS AND SHOWERS WESTWARD OVER OAHU. A MODEL TIME-HEIGHT
CROSS-SECTION OVER OAHU SHOWS THE CAPPING MARINE BOUNDARY
TEMPERATURE INVERSION HEIGHT DEEPENING TO AROUND 8000 TO 9000
FEET. THOUGH MOST ACTIVITY WILL AFFECT WINDWARD SIDES OF THE
ISLAND, THE MOISTURE LEVEL SHOULD BE DEEP ENOUGH TO ALLOW FOR SOME
SHOWERS TO BRIEFLY SPILL OVER THE TERRAIN AND ONTO LEEWARD SIDES.
FOR THE BIG ISLAND, EXPECT LEEWARD SHOWERS TO ONCE AGAIN DEVELOP
OVER THE SOUTH KONA SLOPES IN THIS AFTERNOON DURING PEAK DIURNAL
HEATING. BY TONIGHT, SHOWERS SHOULD BE CONFINED TO WINDWARD AREAS
ON MOST ISLANDS AS MODERATE TRADES AND RESIDUAL MOISTURE FROM THE
EARLIER BAND BEGIN TO EXIT THE REGION.
LATE MONDAY THROUGH WEDNESDAY AFTERNOON, THE SURFACE HIGH WEAKENS
AND MOVES NORTH, ONCE AGAIN ALLOWING A RETURN OF LIGHT TO LOCALLY
MODERATE EASTERLY BACKGROUND FLOW. SCATTERED AFTERNOON LOW CLOUDS
AND ISOLATED SHOWERS WILL LIKELY BE LIMITED TO THE INTERIOR OF
ISLANDS AND OVER ELEVATED TERRAIN AS DIURNALLY DRIVEN SEA BREEZES
PREVAIL. DURING THE NIGHTS ISOLATED SHOWERS MAY AFFECT WINDWARD
LOCATIONS, BUT NOTHING OF SIGNIFICANCE.
LATE WEDNESDAY THROUGH FRIDAY, BOTH THE GFS AND ECMWF HAVE BEEN
CONSISTENT OVER THE LAST SEVERAL MODEL RUNS IN ADVECTING AN AREA
OF DEEPER MOISTURE UP FROM THE SOUTHEAST TOWARDS THE BIG ISLAND.
THIS MOIST LAYER, ROUGHLY 10000 TO 12000 FEET DEEP BY CURRENT
MODEL ESTIMATES, WOULD HELP ENHANCE SHOWER ACTIVITY INITIALLY OVER
THE BIG ISLAND, THEN MAUI COUNTY IF IT HOLDS TOGETHER.
AVIATION
MODERATE AND RATHER STABLE TRADE WINDS WILL PERSIST TODAY. A
SMALL AREA OF LOW LEVEL MOISTURE WITHIN THE TRADES IS PRODUCING
MVFR CONDITIONS OVER WINDWARD SLOPES OF MAUI, MOLOKAI, AND LANAI,
AND AIRMET SIERRA FOR MOUNTAIN OBSCURATION REMAINS IN EFFECT ON
THESE ISLANDS. THE MOISTURE WILL LIKELY SPREAD TO WINDWARD OAHU
THIS MORNING AND REQUIRE AN EXPANSION OF THE AIRMET, WHILE
CONDITIONS IMPROVE ON MAUI. VFR CONDITIONS WILL PREVAIL ELSEWHERE,
EXCEPT FOR ISOLATED MVFR ACROSS LEEWARD TERRAIN IN THE AFTERNOON.
A SHARP, THOUGH WEAK, UPPER LEVEL TROUGH IS PRODUCING MODERATE
TURBULENCE ALOFT OVER THE BIG ISLAND, WHERE AIRMET TANGO IS IN
PLACE ABOVE FL300.
MARINE
A LONG-PERIOD SOUTH-SOUTHWEST (200 DEGREE) SWELL WILL CONTINUE TO FILL
IN TODAY AND PEAK TONIGHT INTO MONDAY BEFORE GRADUALLY DECLINING
THROUGH THE REST OF THE WEEK. BUOY 51002, SOUTH OF THE ISLANDS, IS
OBSERVING AROUND A 4 FOOT SWELL AT 19 SECONDS THIS MORNING, WITH
A PEAK OBSERVATION EXCEEDING 5 FEET. AS A RESULT, SURF HEIGHTS
ALONG EXPOSED SOUTH FACING SHORES ARE FORECAST TO HOVER NEAR HIGH-
END ADVISORY LEVELS TODAY, WHILE WEST-FACING SHORES SEE MODERATE
SURF. THERE IS POTENTIAL THAT AS THE SWELL REACHES ITS PEAK
TONIGHT THAT SURF COULD REACH WARNING LEVELS, ALONG WITH ADVISORY
LEVEL SURF FOR WEST FACING SHORES. SOUTH SHORE SURF WILL REMAIN
ELEVATED THROUGH MUCH OF NEXT WEEK DUE TO THE SLOW DECLINE OF THIS
LARGE SOUTH SWELL AND A SERIES OF CONTINUED OVERLAPPING SOUTHERLY
SWELLS.
THIS SWELL WILL ALSO COINCIDE WITH THE PEAK MONTHLY TIDES WHICH
WILL ADD THE POTENTIAL FOR SIGNIFICANT WAVE RUNUP ON TOP OF MINOR
COASTAL FLOODING POTENTIAL DURING THE MONTHLY PEAK TIDES THROUGH
THE FIRST HALF OF NEXT WEEK. ONCE THE PEAK SWELL PASSES, SOUTH
SHORE SURF WILL REMAIN ELEVATED THROUGH MUCH OF THE WEEK DUE TO
THE SLOW DECLINE OF THIS LARGE SOUTH SWELL AND A SERIES OF
CONTINUED OVERLAPPING SOUTHERLY SWELLS.
VERY LITTLE SWELL ENERGY IS ARRIVING ALONG NORTH FACING SHORES,
KEEPING SURF TINY TO FLAT. A SMALL BUMP IN SURF IS POSSIBLE FOR NORTH-
FACING SHORES ON TUESDAY WITH THE ARRIVAL OF A SMALL NORTHWEST SWELL
AND A SMALLER NORTH SWELL. GENTLE TO MODERATE EAST-NORTHEASTERLY WINDS
EXPECTED THROUGH NEXT WEEK WILL KEEP SURF ALONG EAST FACING SHORES
BELOW SEASONAL AVERAGE.
A COASTAL FLOOD STATEMENT REMAINS IN EFFECT FOR MINOR COASTAL
FLOODING OF VULNERABLE LOW-LYING COASTAL ROADWAYS, DOCKS, BOAT
RAMPS AND OTHER COASTAL INFRASTRUCTURE. KING TIDES COMBINED WITH
WATER LEVELS THAT ARE RUNNING HIGHER THAN PREDICTED WILL LEAD TO
MINOR FLOODING POTENTIAL AROUND THE DAILY PEAK TIDE, WHICH WILL BE
DURING THE LATE AFTERNOON AND EARLY EVENING HOURS, THROUGH AT
LEAST TUESDAY. WHILE MINOR COASTAL FLOODING IS EXPECTED ALONG ALL
SHORELINES, THE COMBINATION OF THE SOUTH-SOUTHWEST SWELL, KING
TIDES AND THE DAILY HIGH TIDE WILL MAKE LOW-LYING COASTAL AREAS
ALONG SOUTH AND WEST SHORES SUSCEPTIBLE TO MORE WIDESPREAD COASTAL
FLOODING THROUGH THE FIRST HALF OF NEXT WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
HIGH SURF ADVISORY UNTIL 6 AM HST TUESDAY FOR NIIHAU-KAUAI
LEEWARD-WAIANAE COAST-KAHOOLAWE-MAUI LEEWARD WEST-KONA-KOHALA-
KAUAI SOUTH-EAST HONOLULU-HONOLULU METRO-EWA PLAIN-MOLOKAI
SOUTHEAST-MOLOKAI LEEWARD SOUTH-LANAI LEEWARD-LANAI SOUTH-MAUI
CENTRAL VALLEY SOUTH-KIPAHULU-SOUTH MAUI/UPCOUNTRY-SOUTH
HALEAKALA-BIG ISLAND SOUTH-BIG ISLAND SOUTHEAST.
DISCUSSION...THOMAS
AVIATION...WROE
MARINE...QUESADA
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