154
FXHW60 PHFO 131349
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
349 AM HST SAT JUN 13 2026
SYNOPSIS
TRADE WINDS WILL REMAIN WEAK TODAY AND ALLOW FOR SEA BREEZE
DEVELOPMENT ALONG COASTAL AREAS BY LATE THIS MORNING INTO THE
AFTERNOON. ISOLATED AFTERNOON SHOWERS WILL BE MAINLY LIMITED TO
INTERIOR REGIONS AND ALONG MOUNTAIN SLOPES. HOWEVER, THESE SHOWERS
SHOULD DISSIPATE BY THIS EVENING WITH THE LOSS OF DIURNAL
HEATING. EXPECT A SLIGHT UPTICK IN SHOWER ACTIVITY ALONG WINDWARD
AREAS SUNDAY INTO MONDAY, AS TRADES STRENGTHEN AND AN AREA OF
MARGINALLY ENHANCED MOISTURE PUSHES ACROSS THE STATE. BY MIDWEEK,
THERE WILL BE A RETURN TO LIGHT FLOW WITH AFTERNOON SEA BREEZE
DEVELOPMENT AND ISOLATED INTERIOR SHOWERS.
DISCUSSION
BENIGN WEATHER CONDITIONS PREVAILED OVERNIGHT WITH LAND BREEZES
HELPING TO KEEP CLOUDS AND SHOWERS OFF THE ISLANDS AND OUT TO SEA.
THE 12Z RAOB SOUNDINGS FROM BOTH LIHUE AND HILO INDICATED A
RATHER SHALLOW AND STABLE MARINE BOUNDARY LAYER WITH CAPPING
TEMPERATURE INVERSION HEIGHT BETWEEN 5000 TO 6000 FEET. A WEAK
SURFACE PRESSURE GRADIENT WILL ONCE AGAIN HELP MAINTAIN LIGHT
BACKGROUND FLOW TODAY, AS SURFACE HIGH PRESSURE RESIDES WELL
NORTHEAST OF THE STATE AND A DISSIPATING FRONTAL SYSTEM APPROACHES
FROM THE NORTHWEST. AS WAS THE CASE YESTERDAY, SEA BREEZES WILL
LIKELY FORM ALONG COASTAL AREAS BY LATE THIS MORNING INTO THE
AFTERNOON. THIS SHOULD AID IN THE DEVELOPMENT OF SCATTERED CLOUDS
AND ISOLATED SHOWERS OVER MAINLY INTERIORS REGIONS AND MOUNTAIN
SLOPES, ESPECIALLY ALONG THE LOWER SOUTH SLOPES OF MAUNA LOA ON
THE BIG ISLAND.
TONIGHT, SURFACE HIGH PRESSURE BEGINS TO STRENGTHEN NORTHEAST OF
THE ISLANDS AND WILL REMAIN ANCHORED IN PLACE THROUGH MONDAY.
IN RESPONSE, LOCAL PRESSURE GRADIENTS WILL TIGHTEN AND TRADE
WINDS SHOULD STRENGTHEN BACK INTO THE MODERATE RANGE. LATEST
SHORT TERM MODEL GUIDANCE DEPICTS AN AREA OF ENHANCED LOW LEVEL
MOISTURE MOVING OVER THE ISLANDS FROM THE EAST NORTHEAST LATE
THIS WEEKEND INTO EARLY NEXT WEEK, CAUGHT UP IN THE TRADE WIND
FLOW. MODEL TIME-HEIGHT CROSS-SECTIONS DEEPEN THE BOUNDARY LAYER
INVERSION HEIGHT TO AROUND 8000 FEET AS THE MOISTURE PASSES
THROUGH. AS REFLECTED IN THE LATEST FORECAST PACKAGE, EXPECT A
SLIGHT UPTICK IN CLOUDS AND SHOWERS ALONG WINDWARD LOCATIONS
SUNDAY INTO MONDAY, MAINLY FROM OAHU TO THE BIG ISLAND.
TUESDAY THROUGH THURSDAY, THE AFOREMENTIONED HIGH MOVES NORTHWARD
AWAY FROM THE ISLANDS, ONCE AGAIN ALLOWING FOR LIGHT EASTERLY
FLOW ACROSS THE STATE. BOTH THE GFS AND ECMWF INDICATE DEEPER LOW
LEVEL MOISTURE STRETCHING FROM EAST TO WEST ACROSS THE BIG ISLAND
WITH DRIER AIR POSITIONED FURTHER NORTH OVER THE SMALLER ISLANDS.
IF THIS SCENARIO COMES TO FRUITION, EXPECT THE MORE ROBUST SHOWER
ACTIVITY TO BE CONCENTRATED OVER THE BIG ISLAND, WHILE MORE
ISOLATED DIURNALLY DRIVEN SHOWERS AND CLOUDS FORM OVER THE SMALLER
ISLANDS INTERIORS.
AVIATION
GENTLE TO MODERATE TRADES PERSIST THROUGH THE WEEKEND, LEADING TO
LOCALIZED SEA BREEZES EACH AFTERNOON. A STABLE AND SOMEWHAT DRY
AIR MASS WILL MAINTAIN MOSTLY VFR CONDITION. ISOLATED MVFR
CEILINGS WILL DEVELOP OVER LEEWARD AND INTERIOR EACH AFTERNOON
AND ACROSS WINDWARD AREAS OVERNIGHT.
NO AIRMETS ARE IN EFFECT.
MARINE
GENTLE TO MODERATE EAST-NORTHEASTERLY WINDS ARE EXPECTED TODAY AS
A WEAK FRONT PASSING FAR NORTH OF THE STATE DISPLACES THE RIDGE
AND KEEPS THE TRADE WINDS TEMPERED. MODERATE TO FRESH EASTERLY
TRADES WILL RETURN SUNDAY THROUGH EARLY NEXT WEEK AS THE SURFACE
RIDGE STRENGTHENS, BUT REMAINS WELL NORTH OF THE AREA.
A COASTAL FLOOD STATEMENT HAS BEEN ISSUED FOR ISOLATED MINOR
COASTAL FLOODING OF VULNERABLE LOW-LYING COASTAL ROADWAYS, DOCKS,
BOAT RAMPS AND OTHER COASTAL INFRASTRUCTURE. PEAK MONTHLY HIGH
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.
SURF ALONG SOUTH AND WEST-FACING SHORES WILL BEGIN TO TREND UP BY
THIS AFTERNOON AS FORERUNNERS ARRIVE FROM A LARGE, LONG-PERIOD SWELL
ORIGINATING FROM SOUTHEAST OF NEW ZEALAND. THIS SWELL PEAKED AT
THE AMERICAN SAMOA BUOYS AROUND 12 FEET 17 SECONDS THURSDAY
AFTERNOON. SURF WILL CONTINUE TO TREND UP TONIGHT, LIKELY
REACHING ADVISORY LEVELS ON SUNDAY BEFORE PEAKING SUNDAY NIGHT
INTO MONDAY NEAR WARNING LEVELS (BUT MOST LIKELY TO REMAIN AT
HIGH-END ADVISORY LEVELS). THIS SWELL WILL ALSO COINCIDE WITH THE
PEAK MONTHLY TIDES WHICH WILL ADD THE POTENTIAL FOR SIGNIFICANT
WAVE RUNUP ON TOP OF THE AFOREMENTIONED MINOR COASTAL FLOODING
POTENTIAL DURING THE FIRST HALF OF NEXT WEEK. 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.
VERY LITTLE SWELL ENERGY IS ARRIVING ALONG NORTH FACING SHORES THIS
MORNING, KEEPING SURF TINY TO FLAT. A SMALL BUMP IN SURF IS POSSIBLE
FOR NORTH-FACING SHORES EARLY NEXT WEEK WITH THE ARRIVAL OF A SMALL
NORTHWEST SWELL AND A SMALLER NORTH SWELL. WEAKER THAN AVERAGE TRADE
WINDS NEAR AND UPSTREAM OF THE ISLANDS WILL PRODUCE BELOW AVERAGE SURF
ALONG EAST-FACING SHORES THROUGH THE WEEKEND AND INTO EARLY NEXT
WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...THOMAS
AVIATION...WROE
MARINE...QUESADA
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