365
FXHW60 PHFO 101420
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
420 AM HST WED SEP 10 2025
SYNOPSIS
AS WEAKENING TROPICAL STORM 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.
DISCUSSION
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. TROPICAL STORM 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
TROPICAL STORM 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
TROPICAL STORM 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. KIKO CONTINUES TO
PRODUCE TROPICAL STORM CONDITIONS ACROSS THE NORTHEAST CENTRAL
OFFSHORE WATERS. A TROPICAL STORM WARNING REMAINS IN EFFECT FOR
THE OFFSHORE WATERS, HOWEVER THE LATEST FORECAST FROM NHC SHOWS
KIKO WEAKENING TO A TROPICAL DEPRESSION BY THIS MORNING.
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 KIKO PASSES TO OUR NORTH.
FIRE WEATHER
HIGHER HUMIDITY WITH LIGHT EAST-SOUTHEAST BREEZES TODAY. BREEZY
TRADES ARE FORECAST TO RETURN TONIGHT. RAIN WILL FOCUS WITHIN
HIGHER TERRAIN AND WINDWARD EXPOSURES THE NEXT COUPLE OF DAYS.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...BLOOD
AVIATION...BOHLIN
MARINE...SHIGESATO
FIRE WEATHER...BLOOD
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