784
FXHW60 PHFO 101454
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
454 AM HST WED SEP 10 2025
UPDATE
KIKO HAS BEEN DOWNGRADED TO A POST-TROPICAL CYCLONE. HAVE UPDATED
THE PREVIOUS AFD BELOW.
SYNOPSIS
AS WEAKENING POST-TROPICAL CYCLONE KIKO SKIMS THE NORTHERN
WINDWARD COASTAL WATERS OF OAHU AND KAUAI EARLY THIS MORNING,
HIGHER MOISTURE AND LIGHT SOUTHEASTERLIES ASSOCIATED WITH THIS
SYSTEM COULD POTENTIALLY LEAD TO AREAS OF TOPOGRAPHICALLY-
ENHANCED PRECIPITATION. ONCE KIKO EXITS STAGE LEFT, MODERATE
TRADES WILL RETURN BY EARLY THURSDAY MORNING. HIGHER RAIN CHANCES
THURSDAY NIGHT AND FRIDAY WITH RELATIVELY DRIER WEEKEND
CONDITIONS.
PREV DISCUSSION
/ISSUED 420 AM HST WED SEP 10 2025/
TODAY'S CHALLENGE FOCUSES ON WHERE RAIN WILL FALL AND WHERE MORE
ORGANIZED SHOWERS WILL ROOT THEMSELVES WITHIN HIGHER TERRAIN LATER
THIS AFTERNOON INTO EVENING. POST-TROPICAL CYCLONE KIKO HAS
INTRODUCED A MORE MOIST AIR MASS TO THE ISLANDS, ESPECIALLY THE
WESTERN HALF OF THE CHAIN, WHERE THIS MORNING'S LIHUE SOUNDING
PRECIPITABLE WATER 1.71 INCHES PLACES IT IN THE UPPER 10% RANGE
(MEAN OF 1.4 INCHES). SWATHS OF HIGHER MOISTURE MOVING UP WITHIN
THE BANDING FEATURES ASSOCIATED WITH KIKO, WHOSE LOW LEVEL
CIRCULATION IS LOCATED APPROXIMATELY 80 MILES NORTH OF TURTLE BAY,
OAHU AT 3 AM HST, WILL PASS OVER THE ISLANDS THE NEXT 12 TO 18
HOURS. THE LIHUE SOUNDING ALSO INDICATED A UNSTABLE ENOUGH PROFILE
(NEAR 1.5K J/KG MU CAPE) TO SUGGEST THAT, WITH LIFT OR WITHIN ANY
DOWNSTREAM PLUME, ROBUST CONVECTION COULD EASILY OCCUR AND
SUSTAIN ITSELF WITHIN THIS MOISTENED NEAR 7K FT BOUNDARY LAYER.
THE POSITIONING OF THESE NEAR NORTH-TO-SOUTH ORIENTATED BANDS OF
HIGHER MOISTURE WILL ULTIMATELY DETERMINE THE HAVE AND THE HAVE
NOTS OF ANY SIGNIFICANT RAINFALL. A WEAK WIND FIELD LEFT IN KIKO'S
WAKE WILL SLOWLY VEER MORE SOUTHEAST TODAY AND THIS WEAK WIND
DIRECTION COULD CAUSE PROBLEMS ACROSS OAHU FROM THE MOLOKAI PLUME
AS WELL AS OVER KAUAI'S HIGHER TERRAIN. AN OUTER BAND THAT IS
CURRENTLY COMING ACROSS THE EASTERN END OF THE STATE IS INCREASING
SHOWER COVERAGE ACROSS WINDWARD BIG ISLAND AND MAUI DURING THE
PRE-DAWN HOURS. SO, WHILE KIKO WILL HAVE NO DIRECT IMPACTS TO THE
ISLANDS, THE INDIRECT IMPACTS WILL COME FROM STATIONARY CELLS
WITHIN THIS FAVORABLE VEERED EAST-SOUTHEAST FLOW THAT COULD EASILY
PRODUCE A QUICK INCH OR TWO OF RAIN WITHIN A HOUR. HIGHER
RESOLUTION MODELING SOLUTIONS ARE NOT FOCUSING THE HIGHEST
PRECIPITATION ON ANY PARTICULAR AREA, BUT THEY ARE SUGGESTING THAT
CONVECTION COULD ANCHOR ALONG OAHU'S KOOLAUS AND BIG ISLAND'S
WINDWARD HILO, PUNA AND KA'U REGIONS. THUS, WHILE WE ARE CURRENTLY
HOLDING OFF ON A STATEWIDE FLOOD WATCH, THE RADAR WILL NEED TO BE
CLOSELY MONITORED TODAY IN THE EVENT THAT ISOLATED AREAS DO
RECEIVE A QUICK 2 TO 4 INCHES, INITIATING DOWNSTREAM FLOODING
ISSUES.
LOCALLY BREEZY TRADES RETURN OVERNIGHT TONIGHT AS UPPER RIDGING
BUILDS IN FROM THE NORTHWEST. A RIBBON OF HIGHER MID-LAYER
MOISTURE PASSING BY FROM THE EAST THURSDAY AFTERNOON AND FRIDAY
WILL INCREASE STATEWIDE RAIN CHANCES WITH THE HIGHEST QPF LIKELY
FOCUSED ALONG MORE EASTERN ISLAND WINDWARD UPSLOPE MAUKA. AN
UNEVENTFUL WEEKEND WHERE MANY LOCALES WILL REMAIN DRY WITH ONLY
BRIEF SHOWERS OCCURRING ALONG EAST-FACING EXPOSURES AND WITHIN
HIGHER TERRAIN. RAIN CHANCES WILL AGAIN BE ON THE RISE NEXT TUESDAY
AND WEDNESDAY AS A LOBE OF HIGHER MOISTURE EXPANDS UP FROM THE
ITCZ AND CLIPS THE STATE.
AVIATION
POST-TROPICAL CYCLONE KIKO WILL CONTINUE ON A WESTWARD TRACK,
DISRUPTING TRADE WINDS AS THE LOW CENTER PASSES JUST NORTH OF THE
WESTERN HAWAIIAN ISLANDS TODAY. DEEP TROPICAL MOISTURE SURROUNDING
KIKO WILL PRODUCE SOME ENHANCED SHOWER ACTIVITY ALONG WIND
CONVERGENCE BANDS ACROSS THE REGION, INCLUDING ISLAND MOUNTAIN AND
INTERIOR SECTIONS IN DAYTIME SEA BREEZES. PERIODS OF MVFR
CONDITIONS WITH +SHRA AND LOW CLOUDS ARE POSSIBLE.
TRADE WINDS BUILD BACK INTO THE REGION AS KIKO WEAKENS AND DEPARTS
THE REGION TOWARDS THE WEST FROM LATER TONIGHT THROUGH THURSDAY.
STRONGER LARGE SCALE WINDS WILL LIMIT DAYTIME ISLAND SEA BREEZES
TO SHELTERED WESTERN MOUNTAIN SLOPES ON THURSDAY.
NO AIRMETS IN EFFECT, AN AIRMET FOR MOUNTAIN OBSCURATION IS
POSSIBLE LATER TODAY AS SHOWER BANDS DEVELOP IN THE WAKE OF KIKO'S
PASSAGE THROUGH THE REGION.
MARINE
POST-TROPICAL CYCLONE KIKO IS ABOUT 70 NM NE OF OAHU THIS MORNING
AND CONTINUES TO TRACK WEST-NORTHWEST JUST NORTH OF THE COASTAL
WATERS. AS KIKO CONTINUES TO TRACK WESTWARD, MODERATE TO LOCALLY
FRESH EAST TO SOUTHEAST TRADES WILL BUILD FROM EAST TO WEST ACROSS
THE ISLAND CHAIN TODAY. THURSDAY, THE HIGH PRESSURE RIDGE WILL
BUILD NORTH OF THE WATERS BRINGING A RETURN TO MODERATE TO LOCALLY
FRESH TRADE WINDS THROUGH THE FORECAST PERIOD.
NEARSHORE BUOYS ACROSS THE STATE EXPOSED TO THE EASTERLY SWELL
FROM KIKO, HAS PEAKED AND IS DROPPING QUICKLY THIS MORNING.
THEREFORE, THE SMALL CRAFT ADVISORY (SCA) FOR SEAS ABOVE 10 FEET
FOR WESTERN WATERS, THE HIGH SURF WARNING AND ADVISORY FOR ALL
EAST FACING SHORES HAVE BEEN CANCELLED.
SURF ALONG SOUTH FACING SHORES WILL REMAIN NEAR THE SUMMERTIME
AVERAGE TODAY AS THE REINFORCING SWELL OUT OF THE SOUTH-SOUTHWEST
PEAKS TODAY BEFORE SLOWLY DECLINING THROUGH THURSDAY. ANOTHER
SMALL BUMP FROM THE SOUTH IS POSSIBLE ON FRIDAY. ADDITIONALLY,
MULTIPLE SMALL PULES OF NORTHWEST TO NORTH- NORTHWEST SWELL ENERGY
WILL GENERATE SMALL SURF ALONG NORTH FACING BEACHES THROUGHOUT
THE WEEK AND INTO THE WEEKEND. A SHORT-LIVED NORTHEAST SWELL IS
POSSIBLE FOR SELECT EXPOSURES AS POST-TROPICAL KIKO PASSES TO OUR
NORTH.
FIRE WEATHER
HIGH HUMIDITY AND LIGHT TO MODERATE WINDS CONTINUE FOR THE NEXT
COUPLE OF DAYS WITH SCATTERED SHOWERS FOCUSED OVER ISLAND
INTERIORS DURING THE AFTERNOON. LOCALLY BREEZY TRADES THEN RETURN
WEDNESDAY NIGHT AS HUMIDITY FALLS TO TYPICAL VALUES.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
UPDATE/DISCUSSION/FIRE...BLOOD
AVIATION...BOHLIN
MARINE...SHIGESATO
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