222
FXHW60 PHFO 081940
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
940 AM HST THU OCT 8 2026
SYNOPSIS
A FLASH FLOODING THREAT PERSISTS FOR OAHU THROUGH THIS AFTERNOON
WITH COMPARATIVELY FEW SHOWERS EXPECTED ELSEWHERE. LIGHT TO
MODERATE TRADES RETURN THIS WEEKEND.
SHORT TERM UPDATE
SHOWERS, SOME HEAVY, CONTINUE THIS MORNING ACROSS THE STATE. THE
HEAVIEST RAIN OVER THE PAST 6 HOURS HAS BEEN OVER OAHU, AND A
FLOOD ADVISORY IN EFFECT UNTIL 11 AM HST. MORE RAIN IS FORECAST
THROUGH THE AFTERNOON, ESPECIALLY ON OAHU. A FLOOD WATCH IS ALSO
IN EFFECT THERE THROUGH 6 PM HST. AN UPDATE WILL BE DONE TO
INCREASE THE CHANCE OF RAIN TODAY ACROSS SOUTHEAST BIG ISLAND.
OTHERWISE THE FORECAST IS IN GOOD SHAPE.
AVIATION
LIGHT TO MODERATE SOUTHERLY WINDS WILL CONTINUE INTO THE
AFTERNOON GIVING WAY TO A MORE EASTERLY SHIFT. RAIN WILL ALSO
CONTINUE WITH INTERMITTENT MVFR CONDITIONS. SCATTERED MVFR
CONDITIONS CAN BE EXPECTED ELSEWHERE.
FOR THE HONOLULU TERMINAL, EXPECT A GRADUAL DECREASE IN WIND GUSTS
AND A SHIFT FROM SOUTHERLY TO SOUTHEAST TONIGHT.
FOR THE LANAI TERMINAL, IFR AND LIFR CONDITIONS HAVE PERSISTED
THIS MORNING WHERE THE CLOUD DECK IS 300 FT. THESE CONDITIONS
SHOULD IMPROVE LATER THIS AFTERNOON.
AIRMET SIERRA IS IN EFFECT FOR TEMPO MOUNTAIN OBSCURATION ACROSS
ALL OF KAUAI AND OAHU. IT IS ALSO IN EFFECT FOR SOUTH THROUGH WEST
FACING PORTIONS OF MOLOKAI AND LANAI. TEMPO IFR CONDITIONS ARE
ALSO POSSIBLE WITHIN THE RAIN SHOWERS CURRENTLY MOVING THROUGH
WESTERN OAHU.
AIRMET TANGO IS IN EFFECT FOR LOW LEVEL TURBULENCE DOWNWIND OF
TERRAIN WHICH IN SOUTHERLY FLOW IS EAST AND NORTH OF ISLAND
MOUNTAINS.
MARINE
GENTLE TO MODERATE SOUTH TO SOUTHEAST WINDS WILL CONTINUE THROUGH
FRIDAY AS A LOW PRESSURE SYSTEM DEEPENS NORTH TO NORTHWEST OF
HAWAII. TROPICAL MOISTURE WILL LIFT FROM THE SOUTH OVER THE
ISLANDS UNDER A COLD UPPER LOW, PRODUCING PERIODS ENHANCED
SHOWERS ACROSS THE STATE WITH THE POTENTIAL FOR A FEW
THUNDERSTORMS NEAR NIIHAU, KAUAI AND OAHU TODAY. A PASSING LOW
LEVEL TROUGH WILL THEN DRIFT FROM EAST TO WEST THROUGH THE ISLANDS
FROM SUNDAY INTO THE FIRST HALF OF NEXT WEEK, POTENTIALLY
EXTENDING THESE UNSTABLE WET WEATHER TRENDS.
SOUTH SWELL WILL CONTINUE INTO NEXT WEEK WITH PULSES OF LONG
PERIOD REINFORCEMENT ARRIVING TODAY AND SATURDAY. SURF WILL
REMAIN A FEW FEET BELOW ADVISORY LEVELS ALONG SOUTH FACING SHORES.
SMALL TO MODERATE SURF ALONG NORTH AND WEST FACING SHORES WILL
CONTINUE THROUGH THE REST OF THE WEEK AS SWELL ENERGY IS
REINFORCED BY THE SLOWLY MOVING SURFACE LOW NORTH TO NORTHWEST OF
THE HAWAIIAN ISLANDS. A LARGER SWELL WILL ARRIVE AROUND TUESDAY,
BOOSTING NORTH AND WEST SHORE SURF TO JUST BELOW ADVISORY
THRESHOLDS. SURF ALONG EAST FACING SHORES WILL REMAIN SMALL AS
LOCAL WINDS REMAIN FAIRLY WEAK.
PREV DISCUSSION
ISSUED AT 522 AM HST THU OCT 8 2026
WIDELY SCATTERED MODERATE TO LOCALLY HEAVY SHOWERS ARE ONGOING
FROM KAUAI TO OAHU WITH TENDENCY FOR INCREASED ORGANIZATION IN THE
KAUAI CHANNEL BENEATH MATURE RIGHT ENTRANCE DYNAMICS. HEAVY RAIN
RATES OF 1 TO LOCALLY 2 INCHES PER HOUR HAVE BEEN QUITE ISOLATED
THUS FAR, BUT ARE BEGINNING TO ALIGN WITHIN THE FLOW-PARALLEL BAND
THAT HAS FORMED IN THE CHANNEL. CLOUD TOP COOLING ASSOCIATED WITH
THIS BAND IS ASSOCIATED WITH A MODEST INCREASE IN THUNDERSTORM
ACTIVITY AND SUGGESTS THE INTENSIFICATION PROCESS WILL CONTINUE IN
THE NEAR TERM, THOUGH IT IS CLEAR AT THIS POINT THAT ORGANIZATION
WILL CONTINUE TO STRUGGLE DUE TO THE LACK OF A SURFACE-BASED
FORCING MECHANISM. REGARDLESS, EASTWARD PROGRESS OF THIS BAND WILL
CRITICAL FOR THIS MORNING'S OAHU FORECAST AND SUBSEQUENT FLASH
FLOODING POTENTIAL. THOUGH NOT PARTICULARLY ACCURATE IN THEIR
DEPICTION OF THE POSITION OF THE PRIMARY BAND OF HEAVY RAIN, THE
GUIDANCE IS GENERALLY IN AGREEMENT THAT ONCE FORMED EASTWARD
PROGRESS WILL BE MINIMAL. WHILE CONVECTION MAY INHERENTLY DEVELOP
A TENDENCY TO PROPAGATE EASTWARD WITH TIME, THE GREATEST
ORGANIZATION IS EXPECTED TO REMAIN IN THE KAUAI CHANNEL. WITH THAT
SAID, A SECONDARY SURGE OF DEEP MOISTURE IS STILL POISED TO LIFT
ACROSS OAHU DURING THE MORNING HOURS AND THE MODEST ASCENT FIELD
AWAY FROM THE PRIMARY BAND MAY STILL BE SUFFICIENT TO MAINTAIN
ELEVATED RAIN RATES FOR AT LEAST THE NEXT SEVERAL HOURS.
TO THE SOUTHWEST, CHANNEL 10/LOW-LEVEL WATER VAPOR IMAGERY DEPICTS A
PLUME OF DRY AIR LIFTING TOWARD KAUAI WITHIN A CORRIDOR OF BACKING
MID-LEVEL SOUTHERLIES. THE ARRIVAL OF THIS DRY AIR INTRUSION WILL
BRING A QUICK RETURN TO STABILITY AND WILL SIGNAL THE END OF ANY
FLOODING THREAT FOR KAUAI UPON ITS ARRIVAL LATER THIS MORNING.
HOWEVER, THE LOSS OF A WESTERLY COMPONENT TO THE MID-LEVEL FLOW WILL
DELAY THE ARRIVAL OF THIS DRY AIR FOR OAHU WHERE PERIODS OF SHOWERS,
SOME HEAVY, WILL CONTINUE THROUGH MUCH OF THE DAY. THE LEAD EDGE
OF THIS DRY AIR IS ALSO ENHANCING MID-LEVEL CONVERGENCE AND
HELPING TO ORGANIZE CONVECTION UPSTREAM OF OAHU. THE FLOOD WATCH
REMAINS IN PLACE, THOUGH IT IS INCREASINGLY TENUOUS FOR KAUAI
WHICH MAY BE DROPPED LATER THIS MORNING.
TROPICAL MOISTURE CHARACTERIZED BY PWATS AROUND 2" WILL REMAIN IN
PLACE INTO THE FIRST HALF OF THE WEEKEND, BUT THE WAVE OF DEEP
SATURATION THAT SPREAD OVER THE ISLANDS LAST NIGHT INTO THIS MORNING
WILL BE LONG GONE TO THE NORTH BY THEN. THIS LEAVES THE ISLANDS IN
AN AREA OF VERY BROAD, WEAK ASCENT EAST OF LINGERING RIGHT ENTRANCE
DYNAMICS LIKELY WITHOUT SUFFICIENT FORCING TO GENERATE MEANINGFUL
SHOWER ACTIVITY. WHILE ISOLATED NUISANCE FLOODING CAN'T BE RULED OUT
LATE THIS EVENING INTO FRIDAY, MAINLY FROM OAHU THROUGH MAUI COUNTY,
IT IS UNLIKELY TO WARRANT AN EXTENSION IN TIME OR SPACE TO THE FLOOD
WATCH, ESPECIALLY CONSIDERING THIS EVENT'S UNDERWHELMING PERFORMANCE
THUS FAR.
BY FRIDAY, THE GRADIENT MAY BE SUFFICIENTLY LIGHT TO SUPPORT SEA
BREEZE DEVELOPMENT AND POCKETS OF HEAVY DOWNPOURS ON ANY/ALL ISLANDS
DURING THE AFTERNOON AND THEN MAUI AND THE BIG ISLAND AGAIN OVER THE
WEEKEND. RETURNING MODERATE TRADES DURING THIS TIME WILL EVENTUALLY
LIMIT AFTERNOON CONVERGENCE OVER MOLOKAI, OAHU, AND KAUAI FAVORING A
RETURN TO A MODEST COVERAGE OF CLOUDS AND SHOWERS OVER WINDWARD AND
MAUKA ZONES AS EARLY AS SATURDAY. DEWPOINTS RETURN TO MORE TYPICAL
VALUES IN THE 60S SATURDAY NIGHT INTO SUNDAY.
FIRE WEATHER...
MOIST AND HUMID CONDITIONS UNDER MODERATE SOUTH WINDS CONTINUE
THROUGH TODAY. THE CHANCE FOR WIDESPREAD RAINFALL WILL DIMINISH ON
FRIDAY WHILE HUMID AND LIGHT SOUTHEAST WINDS PREVAIL. LIGHT TO
MODERATE EASTERLY TRADE WINDS ARE EXPECTED THIS WEEKEND. THE
INVERSION HAS BEEN WIPED OUT AND WILL REDEVELOP AS TRADES RETURN
THIS WEEKEND.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 6 PM HST THIS EVENING FOR CENTRAL OAHU-EAST
HONOLULU-EWA PLAIN-HONOLULU METRO-KOOLAU LEEWARD-KOOLAU WINDWARD-
OAHU NORTH SHORE-OLOMANA-WAIANAE COAST-WAIANAE MOUNTAINS.
DISCUSSION...JVC
AVIATION...PECHACEK
MARINE...FOSTER
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