878
FXHW60 PHFO 080151
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
351 PM HST SUN SEP 7 2025
SYNOPSIS
A STABLE, LIGHT TO MODERATE TRADE WIND FLOW WILL PRODUCE LIGHT
RAINFALL OVER WINDWARD SLOPES TONIGHT, AND DRIER AIR MOVING IN
FROM THE EAST ON MONDAY WILL LEAD TO A DECREASE IN SHOWER
ACTIVITY ON MOST ISLANDS. HURRICANE KIKO IS FORECAST TO PASS
NORTH OF THE ISLAND CHAIN ON TUESDAY AND WEDNESDAY, DISRUPTING
THE TRADE WINDS, PRODUCING INCREASED HUMIDITY WITH AREAS HEAVY
RAINFALL, AND GENERATING LARGE SURF ALONG EAST FACING SHORES.
DISCUSSION
SEA BREEZES HAVE OVERPOWERED A WEAK TRADE WIND FLOW TODAY AS
STABLE CONDITIONS REMAIN IN PLACE. TRADES ARE SUPPRESSED AS THE
LOCAL PRESSURE GRADIENT HAS BEEN WEAKENED BY A TROUGH SITTING
ROUGHLY 200 MILES NORTH OF KAUAI. THE UPPER-LEVEL LOW SUPPORTING
THIS TROUGH WEAKENS CONSIDERABLY OVER THE ISLANDS, ALLOWING A
LINGERING MID-LEVEL RIDGE TO MAINTAIN STABLE CONDITIONS WITH AN
INVERSION HOLDING BETWEEN 5,000 TO 8,000 FT. A VERY DIFFUSE AREA
OF LOW- LEVEL MOISTURE WITHIN THE WEAK TRADE WIND FLOW MANAGED TO
PRODUCE ISOLATED MODEST RAINFALL ON MAUI COUNTY AND OAHU TODAY,
WHILE OTHER AREAS HAVE REMAINED MOSTLY DRY. AS THIS MOISTURE
PUSHES SLOWLY WESTWARD OVERNIGHT, EXPECT HIGHER CHANCES FOR MAINLY
LIGHT SHOWERS TO BE FOCUSED ON WINDWARD OAHU AND EVENTUALLY
KAUAI.
EXCEPT FOR A FEW LINGERING SHOWERS NEAR KAUAI AND OAHU IN THE
MORNING, A SLOT OF RATHER DRY CONDITIONS WILL SPREAD FROM EAST TO
WEST ON MONDAY AS HURRICANE KIKO APPROACHES THE REGION. TOWARDS
SUNSET, MOISTURE ALONG THE WESTERN FLANK OF WEAKENING KIKO WILL
NEAR THE WINDWARD COASTS OF THE BIG ISLAND AND MAUI.
THE LATEST NATIONAL HURRICANE CENTER FORECASTS CONTINUE TO SHOW
KIKO WEAKENING TO A TROPICAL STORM AS IT PASSES NORTH OF THE
ISLANDS TUESDAY AND WEDNESDAY. CONFIDENCE IN THIS SCENARIO IS
INCREASING, THOUGH INTERESTS IN HAWAII SHOULD CONTINUE TO MONITOR
OFFICIAL FORECASTS FOR KIKO. MOISTURE ALONG THE PERIPHERY OF THE
SYSTEM WILL SPREAD OVER THE STATE MONDAY NIGHT AND TUESDAY.
INITIALLY, THIS WILL PROVIDE AN INCREASE IN CLOUDS AND MAINLY
WINDWARD SHOWERS, BUT AS TRADE WINDS BECOME DISRUPTED, AFTERNOON
SEA BREEZES WILL LIKELY TRIGGER SPOTTY INTERIOR RAINFALL. THESE
SHOWERS COULD BE LOCALLY HEAVY IN PLACES, AND WE CANNOT RULE OUT A
BRIEF THUNDERSTORM AS THE ATMOSPHERE DESTABILIZES ON TUESDAY. AS
DEW POINTS CREEP INTO THE LOW TO MID 70S, RATHER HUMID CONDITIONS
WILL PREVAIL. IN ADDITION, LARGE SURF WILL AFFECT EAST FACING
SHORES, AND SEE THE MARINE SECTION OF THIS DISCUSSION FOR MORE
DETAILS.
AS KIKO MOVES OFF TO THE NORTHWEST OF THE STATE ON WEDNESDAY
NIGHT AND THURSDAY, MODERATE TRADE WINDS AND A RIDGE ALOFT ARE
EXPECTED TO BUILD IN FROM THE EAST. THE RESULTING STABLE
CONDITIONS WILL BRING A DRIER AIR MASS WITH A TYPICAL PATTERN OF
WINDWARD RAINFALL AND DEW POINTS DROPPING BACK INTO THE MID 60S.
AVIATION
WINDS WILL REMAIN RATHER LIGHT THROUGH TONIGHT, WITH WIDESPREAD
LAND AND SEA BREEZES. CLOUDS AND ISOLATED SHOWERS WILL CONTINUE
OVER LEEWARD AND INTERIOR AREAS THROUGH THIS EVENING, WITH SOME
CLEARING OVERNIGHT. LIGHT TO MODERATE TRADES EXPECTED ON MONDAY,
WITH LOCALIZED LAND AND SEA BREEZES. EXPECT AN INCREASE IN CLOUDS
AND SHOWERS TOMORROW AFTERNOON AS MOISTURE ASSOCIATED WITH
TROPICAL CYCLONE KILO STARTS TO FILTER INTO THE REGION. BRIEF MVFR
IS POSSIBLE WITH ANY SHOWERS. OTHERWISE, EXPECT MAINLY VFR ACROSS
THE STATE, WITH AN INCREASING CHANCE OF MVFR CIGS ON MONDAY.
TROPICAL CYCLONE KIKO WILL APPROACH THE HAWAIIAN ISLANDS FROM THE
SOUTHEAST OVER THE NEXT COUPLE OF DAYS. THE NATIONAL HURRICANE
CENTER IS CURRENTLY FORECASTING KIKO TO PASS NORTH OF THE ISLANDS
ON TUESDAY. ANY DEVIATION SOUTH OF THIS FORECAST TRACK MAY RESULT
IN WIND AND RAIN IMPACTS TO THE STATE.
NO AIRMETS ARE IN EFFECT NOR EXPECTED THROUGH TONIGHT. AIRMET
SIERRA FOR TEMPO MOUNTAIN OBSCURATION MAY BE NECESSARY ON MONDAY
AS MOISTURE FROM TROPICAL CYCLONE KIKO MOVES INTO THE AREA.
MARINE
A WEAK TROUGH NORTH OF THE STATE WILL CONTINUE TO DRIFT WESTWARD
AND AWAY FROM THE STATE THROUGH MONDAY. AS THIS TROUGH MOVES AWAY,
A BRIEF RETURN OF MODERATE TO LOCALLY FRESH TRADES IS EXPECTED ON
MONDAY. TRADES COULD STILL BE LIGHT ENOUGH FOR LOCALIZED SEA
BREEZES DURING THE DAY MONDAY ESPECIALLY OVER THE WESTERN HALF OF
THE STATE.
ATTENTION THEN TURNS TO HURRICANE KIKO, WHICH WAS LOCATED
APPROXIMATELY 550 NM E OF HILO THIS AFTERNOON. HURRICANE KIKO
CONTINUES TO TRACK WEST-NORTHWEST IN THE CENTRAL PACIFIC, AND
ACCORDING TO THE LATEST FORECAST FROM THE NATIONAL HURRICANE
CENTER, IS EXPECTED TO ENTER OUR OFFSHORE WATERS MONDAY NIGHT AS A
WEAKENING HURRICANE. KIKO WILL THEN CONTINUE TO MOVE WEST-NORTHWEST
THROUGH THE OFFSHORE WATERS AS IT WEAKENS TO TROPICAL STORM
STATUS. A HURRICANE WARNING REMAINS IN EFFECT FOR THE OFFSHORE
WATERS WITH HURRICANE CONDITIONS EXPECTED OVER THE E AND NE
OFFSHORE WATERS MONDAY AND MONDAY NIGHT. AS FAR AS THE COASTAL
WATERS, CONFIDENCE IS INCREASING FOR KIKO TO STAY NORTH OF THE
COASTAL WATERS. ALTHOUGH NO WIND IMPACTS ARE EXPECTED OVER THE
COASTAL WATERS, A QUICK RISE OF WAVE HEIGHTS ARE EXPECTED MONDAY
NIGHT INTO TUESDAY AS KIKO PASSES.
SURF ALONG EAST FACING SHORES WILL SLOWLY RISE THROUGH MONDAY AS
SWELL ENERGY FROM TROPICAL CYCLONE KIKO ARRIVES. LATEST BUOY
OBSERVATIONS FROM HILO AND BUOY 51004 SHOW SOME INCREASE IN THE 10
SECOND SPECTRAL BANDS, BUT ONLY A SUBTLE INCREASE IN THE LONGER
PERIODS. THIS SUGGESTS SURF WILL LIKELY COME IN BELOW GUIDANCE IN
THE NEAR-TERM WITH SURF LIKELY STAYING BELOW ADVISORY THRESHOLDS
THROUGH MONDAY. ALTHOUGH AS KIKO NEARS THE STATE LATE MONDAY INTO
TUESDAY, WE SHOULD SEE A RAPID INCREASE OF SWELL WITH SURF HEIGHTS
POSSIBLY REACHING LOW END HIGH SURF WARNING LEVELS MONDAY NIGHT
INTO TUESDAY ALONG EAST FACING SHORES. THE RISE IN SURF WILL BE
SHORT-LIVED WITH A STEADY DECLINE EXPECTED TUESDAY THROUGH TUESDAY
NIGHT. SURF WILL LIKELY DROP WELL BELOW ADVISORY THRESHOLDS BY
WEDNESDAY. NOTE, PEAK SURF HEIGHTS WILL BE HIGHLY DEPENDENT ON
THE TRACK AND INTENSITY OF KIKO AS IT NEARS THE STATE.
A MODERATE LONG PERIOD SOUTH-SOUTHWEST SWELL WILL PEAK TODAY
HELPING TO BUILD SURF ABOVE THE SUMMER AVERAGE. AS THIS SWELL
DECLINES ON MONDAY, ANOTHER REINFORCING SWELL OUT OF THE SOUTH-
SOUTHWEST IS EXPECTED ON TUESDAY. THIS SHOULD HELP MAINTAIN SURF
NEAR OR SLIGHTLY ABOVE THE SUMMER AVERAGE THROUGHOUT THE FIRST
HALF OF THE WEEK. ADDITIONALLY, MULTIPLE SMALL PULES OF NORTHWEST
SWELL ENERGY WILL GENERATE SMALL SURF ALONG NORTH FACING BEACHES
THROUGHOUT THE WEEK.
PEAK MONTHLY HIGH TIDES, COMBINED WITH WATER LEVELS RUNNING
HIGHER THAN PREDICTED, MAY LEAD TO MINOR FLOODING ALONG THE
SHORELINE AND IN LOW LYING COASTAL AREAS. A COASTAL FLOOD
STATEMENT REMAINS IN EFFECT THROUGH THIS AFTERNOON. COASTAL FLOOD
STATEMENT IS EXPECTED TO BE CANCELLED LATER TODAY.
FIRE WEATHER
WINDS ARE FORECAST TO REMAIN BELOW CRITICAL FIRE WEATHER
THRESHOLDS FOR THE NEXT FEW DAYS. A NARROW SLOT OF VERY DRY AND
STABLE AIR WILL MOVE OVER THE ISLANDS FROM EAST TO WEST ON THE
WEAK TRADE WIND FLOW MONDAY. THIS COULD PUSH THE INVERSION DOWN TO
AROUND 4,000 FEET AND PRODUCE VERY LOW HUMIDITY AT HIGHER
ELEVATIONS OF THE KAALA FIRE IN THE HAMAKUA DISTRICT OF THE BIG
ISLAND. INCREASED HUMIDITY AND HIGHER CHANCES FOR RAINFALL ARE
EXPECTED MONDAY NIGHT INTO WEDNESDAY AND TROPICAL CYCLONE KIKO
PASSES NORTH OF THE STATE.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...WROE
AVIATION...AHUE
MARINE...KINO
FIRE WEATHER...WROE
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