818
FXHW60 PHFO 120648
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
848 PM HST WED MAR 11 2026
SYNOPSIS
A POWERFUL KONA STORM WILL IMPACT THE STATE THROUGH THE WEEKEND,
BRINGING MULTIPLE HAZARDS TO THE ISLANDS INCLUDING SIGNIFICANT
FLASH FLOODING, DAMAGING WINDS, AND STRONG TO SEVERE
THUNDERSTORMS. FLOODING CONCERNS WILL CONTINUE OVER KAUAI THIS
EVENING AND SPREAD TO OAHU LATE TONIGHT, THEN GRADUALLY EXPAND
EASTWARD ACROSS THE ISLAND CHAIN THROUGH THE WEEK. THE POTENTIAL
FOR STRONG TO SEVERE THUNDERSTORMS AND MORE WIDESPREAD FLASH
FLOODING WILL INCREASE LATE IN THE WEEK AND INTO THE WEEKEND.
SHORT TERM UPDATE
LOOKING INTO THE WATER VAPOR SATELLITE CHANNEL THIS EVENING,
MULTIPLE SMALLER SCALE UPPER LOWS ARE SWIRLING AROUND A LARGER
COLD CORE REGION OF LOW PRESSURE NORTHWEST OF THE STATE. THE
CLOSEST OF THESE SMALLER UPPER LOWS LINGERS ROUGHLY 300 MILES
NORTH OF MAUI. ADDITIONALLY MULTIPLE UPPER TROUGHS WILL SWING
THROUGH THE HAWAIIAN ISLANDS OVER THE NEXT FEW DAYS. EACH OF THESE
TROUGHS WILL HAVE A NEGATIVE TILT AS THEY REACH THE ISLANDS,
FORCING PULSES OF HEAVY SHOWERS AND THUNDERSTORMS TO DEVELOP OVER
THE STATE AS EACH TROUGH PASSES OVER THE HAWAII REGION.
ALTHOUGH ON A LARGER SCALE THERE WILL BE BRIEF DOWN TURNS IN THE
SEVERITY OF THE WEATHER IMPACTS FROM ISLAND TO ISLAND BETWEEN THE
PASSING UPPER LEVEL TROUGHS. YET ON THE SMALLER SCALE (MESOSCALE),
HEAVY SHOWER BANDS MAY BREAKOUT AT ANY TIME IN THIS HIGHLY
UNSTABLE ENVIRONMENT, POTENTIALLY PRODUCING THUNDERSTORMS, STRONG
WIND GUSTS AND FLOOD THREATS OVER ANY ISLAND. NONE OF OUR FORECAST
GUIDANCE TOOLS HANDLE THE FORMATION AND DEVELOPMENT OF THESE
SMALLER SCALE CONVECTIVE BANDS VERY WELL, WHICH SIMPLY ADDS TO THE
CHALLENGES OF FORECASTING THE HOUR BY HOUR IMPACTS FOR EACH
ISLAND DURING THIS LONG LIVED KONA STORM SYSTEM.
THE FORECAST GRIDS THIS EVENING APPEAR TO BE WELL ON TRACK. A
MINOR UPDATE WAS CHANGED IN THE FORECAST THIS EVENING TO INCLUDE
ICING CONDITIONS PRODUCED BY AREAS OF FREEZING FOG OVER THE BIG
ISLAND SUMMITS ABOVE 12000 FEET ELEVATION. A WINTER WEATHER
ADVISORY FOR MAUNA KEA AND MAUNA LOA WAS ISSUED THIS EVENING TO
COVER THIS ICING THREAT.
PREV DISCUSSION
ISSUED AT 348 PM HST WED MAR 11 2026
TONIGHT. NE-SW ORIENTED MOISTURE AXIS IN PLACE OVER THE ISLANDS
SUPPORTS ONGOING SHOWER ACTIVITY AS THE MID AND UPPER LEVELS SLOWLY
DESTABILIZE. THESE SHOWERS ARE ANCHORED ALONG A CORRIDOR OF
WEAKLY CONFLUENT SW FLOW AND WILL EVOLVE EASTWARD THROUGH TONIGHT
THROUGH MAUI COUNTY TONIGHT. PALTRY CONVERGENCE IS LIKELY TO LIMIT
POTENTIAL FOR ORGANIZATION AND MEANINGFUL HEAVY RAIN TONIGHT.
THURSDAY. THE NEXT WAVE OF SHOWERS IN THE SEQUENCE IS BEGINNING TO
MATERIALIZE ALONG THE SAME MOISTURE AXIS WELL SOUTH OF KAUAI TODAY.
STELLAR LEFT EXIT JET SUPPORT AND STEADY DYNAMIC FORCING ALOFT WILL
ALLOW THIS DEVELOPING BAND OF SHOWERS TO INTENSIFY AS IT REACHES
KAUAI AND POSSIBLY OAHU EARLY THURSDAY. LAPSE RATES ON THE ORDER
OF 7C/KM AND 500MB TEMPERATURES AROUND -13C WILL FAVOR EMBEDDED
THUNDERSTORMS. DESPITE THE INCREASINGLY FAVORABLE THERMODYNAMIC
ENVIRONMENT, LOW-LEVEL CONVERGENCE WILL BE LACKING FOR MUCH OF THE
DAY THURSDAY. THIS WILL LIKELY LEAD TO POORLY ORGANIZED BATCHES OF
HEAVY RAINFALL AND/OR THUNDERSTORMS THROUGH AT LEAST THE FIRST
HALF OF THE DAY. ADDITIONALLY, THE LEFT EXIT CIRCULATION AND
LOCAL PRESSURE FALLS WILL FORCE WINDS TO STEADILY RAMP UP DURING
THURSDAY WITH 850MB WINDS REACHING 35 KTS BY THURSDAY EVENING AND
SUSTAINED SOUTHERLIES IN THE VICINITY OF KAUAI AROUND 20-25KTS.
STRONG SOUTHERLY MOISTURE TRANSPORT MAY FAVOR FAIRLY WIDESPREAD
SHOWERS BY AFTERNOON, BUT GRADUALLY STRENGTHENING SURFACE
CONVERGENCE WILL INCREASINGLY PLACE THE FOCUS ON THE DEVELOPING
HEAVY RAIN BAND OVER KAUAI. AN INCREASINGLY ORGANIZED BAND OF
HEAVY RAIN AND THUNDERSTORMS IS EXPECTED TO BE TAKING SHAPE OVER
KAUAI NO LATER THAN THURSDAY EVENING.
THURSDAY NIGHT THROUGH SATURDAY. THIS REPRESENTS THE PERIOD OF
GREATEST CONCERN AND THE POTENTIAL TIMING FOR CONSIDERABLE IMPACTS
TO LIFE AND PROPERTY. 850MB LOW-LEVEL JET FURTHER RAMPS UP TO NEARLY
50 KTS ON THURSDAY AS SUSTAINED SOUTHERLIES SETTLE AROUND 25 KTS. AS
USUAL, DOWNSLOPING POTENTIAL EXISTS BUT IS UNCERTAIN. SUSPECT POWER
OUTAGES AND DOWNED TREES WILL BE COMMON BY LATE THURSDAY NIGHT INTO
EARLY FRIDAY, PARTICULARLY WHERE SOIL IS WATER LOGGED. OF NOTE, A
STRONG PUNCH OF MID LEVEL DRY AIR AND SUBSIDENCE IMPINGES ON KAUAI
AND OAHU DURING THE DAY SATURDAY WHEN THE WIND FIELD STILL REMAINS
QUITE STRONG. THIS MAY REPRESENT EVEN GREATER POTENTIAL FOR
DOWNSLOPING WINDS TO DEVELOP. THEREFORE, A HIGH WIND WATCH HAS
BEEN ISSUED FOR THE LOWER ELEVATIONS BEGINNING THURSDAY NIGHT AND
CONTINUING THROUGH SATURDAY NIGHT FOR KAUAI THROUGH MAUI. AN HWW
FOR THE BIG ISLAND HAS LIKEWISE BEEN ISSUED WITH A START TIME OF
EARLY FRIDAY. THIS WATCH WILL LATER BE CONVERTED TO EITHER A WIND
ADVISORY OR A HIGH WIND WARNING AS DOWNSLOPING POTENTIAL BECOMES
MORE CLEAR, THOUGH THE AFOREMENTIONED DRY INTRUSION INCREASES
CONFIDENCE THAT STRONG DOWNSLOPING WINDS WILL OCCUR IF NOT DURING
THE ENTIRE WATCH PERIOD, THEN AT LEAST DURING THE TAIL END OF IT
SAT-SAT NIGHT.
THIS PERIOD WILL ALSO BE CHARACTERIZED BY INTENSE RAIN RATES,
THUNDERSTORMS, AND THE POTENTIALLY SERIOUS FLASH FLOODING. THE MOST
INTENSE RAINFALL WILL BE FOCUSED ALONG THE RAPIDLY STRENGTHENING
FRONTAL ZONE AS IT SLOWLY PROGRESSES EASTWARD THROUGH THE STATE.
THIS BAND WILL DEVELOP OVER KAUAI BY LATE THURSDAY, REACH OAHU
DURING FRIDAY AND MAUI COUNTY LATE FRIDAY INTO FRIDAY NIGHT. THE
HEAVY RAIN AXIS FINALLY REACHES THE BIG ISLAND ON SATURDAY, FOCUSING
HEAVY RAIN ALONG LEEWARD AREAS. ALSO SUSPECT SHOWERS WILL RAMP UP
DURING THIS TIME FRAME OVER THE SE SLOPES OF THE BIG ISLAND
POTENTIALLY RESULTING IN SEVERAL INCHES OF RAIN IN ADVANCE OF THE
HEAVY RAIN BAND. THERE IS ALSO A SLIGHT RISK FOR SEVERE
THUNDERSTORMS. WIND PROFILES ARE LARGELY UNIDIRECTIONAL OUT OF THE
SW WHICH WILL FAVOR A PRIMARY THREAT OF WIND. HOWEVER, LARGE HAIL
(1" DIAMETER OR GREATER) IS ALSO NOT OUT OF THE QUESTION WITH ANY
PARTICULARLY INTENSE THUNDERSTORMS. IT SHOULD BE NOTED THAT THE
HEAVY RAIN BAND IS FORECAST TO MOVE SLOWLY BUT STILL BE RATHER
PROGRESSIVE IN NATURE. SHOULD IT STALL OVER AN ISLAND, THE THREAT
FOR SEVERE FLOODING WOULD DRASTICALLY INCREASE.
FINALLY, BIG ISLAND AND HALEAKALA SUMMITS WILL SEE WINDS RAMP UP
FRIDAY INTO SATURDAY. GUSTS OVER 100 MPH CAN BE EXPECTED ON THE BIG
ISLAND WITH LESSER GUSTS OF 80-90 MPH DEVELOPING ON HALEAKALA SUMMIT
BY EARLY SATURDAY. THIS WILL COINCIDE WITH THE PERIOD OF HEAVIEST
PRECIP IN THESE AREAS. BLIZZARD CONDITIONS ARE THEREFORE ANTICIPATED
ON THE BIG ISLAND SUMMITS. THE HIGH WIND WATCH AND WINTER STORM
WATCH FOR THE SUMMITS REMAIN IN EFFECT.
SUNDAY ONWARD. MOIST SW FLOW POTENTIALLY FAVORS CONTINUING SHOWERS,
THOUGH OF DIMINISHED INTENSITY OVER LEEWARD BIG ISLAND. THE NEXT
ROUND OF MID-LEVEL HEIGHT FALLS APPROACHES DURING THE MIDDLE OF NEXT
WEEK POTENTIALLY REACTIVATING THE LINGERING BAND OF MOISTURE OVER
THE ISLANDS.
AVIATION
SHOWER ACTIVITY WILL GENERALLY BE ON THE DECREASE THIS EVENING
WITH VFR CONDITIONS EXPECTED AT MANY AREAS. SOME AREAS COULD SEE
LOW CLOUDS CONTINUE TO PERSIST THROUGH THE NIGHT DUE TO THE RECENT
MOISTURE. THE NEXT WAVE OF SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO ARRIVE THURSDAY MORNING AND WILL BRING ANOTHER ROUND OF MVFR
CONDITIONS WITH BRIEF PERIODS OF IFR/LIFR CONDITIONS.
AIRMET SIERRA REMAINS IN EFFECT FOR MOUNTAIN OBSCURATION FOR ALL
OF KAUAI, OAHU AND MAUI COUNTIES, AS WELL AS THE SOUTH AND
SOUTHEAST PORTIONS OF THE BIG ISLAND. THE AIRMET MAY BE BRIEFLY
CANCELLED, BUT WILL LIKELY BE NEED TO BE REISSUED BY THURSDAY
MORNING AS THE NEXT WAVE OF MOISTURE ARRIVES.
MARINE
ISSUED AT 348 PM HST WED MAR 11 2026
A POWERFUL KONA STORM WILL RESULT IN HEAVY RAIN, THUNDERSTORMS,
AND ROUGH SEAS FOR THE ISLANDS AND ADJACENT COASTAL WATERS THROUGH
THE REST OF THIS WEEK. TODAY'S SCATTEROMETER PASSES SHOWED WINDS
HAVE SIGNIFICANTLY DIMINISHED AROUND THE BIG ISLAND, THOUGH THEY
REMAIN FRESH NEAR KAUAI. AS A RESULT, THE SMALL CRAFT ADVISORY
(SCA) HAS BEEN CANCELLED. A RELATIVE LULL IN WINDS IS FORECAST
TONIGHT BEFORE STRONG SOUTHERLY WINDS REDEVELOP THURSDAY
AFTERNOON. WINDS ARE LIKELY TO APPROACH, OR POSSIBLY REACH, GALE-
FORCE FOR PORTIONS OF THE AREA AS EARLY AS THURSDAY NIGHT OR
FRIDAY AND LAST INTO THE WEEKEND IN ASSOCIATION WITH A BAND OF
HEAVY RAINFALL AND THUNDERSTORMS PUSHING EASTWARD ACROSS THE
FORECAST AREA.
A SERIES OF SMALL, MEDIUM- TO LONG-PERIOD WEST-NORTHWEST SWELLS
WILL BRING SMALL SURF TO NORTH AND WEST FACING SHORES THROUGH THE
REST OF THE WEEK. KAUAI WILL BLOCK SOME OF THIS SWELL ENERGY FROM
REACHING OAHU AND MAUI, BUT IT WILL MAKE IT INTO THE WEST FACING
SHORES OF THE BIG ISLAND. THE CURRENT SWELL WILL BEGIN TO DIMINISH
LATE THURSDAY BEFORE THE NEXT WEST-NORTHWEST SWELL BUILDS FRIDAY INTO
THE WEEKEND. ADDITIONALLY, A SMALL, MEDIUM-PERIOD NORTH SWELL
ORIGINATING FROM ALASKA PENINSULA GAP WINDS IS EXPECTED TO ARRIVE
THURSDAY NIGHT AND CONTINUE INTO THE WEEKEND.
CHOPPY SURF ALONG EAST-FACING SHORES WILL CONTINUE TO TREND DOWNWARD
AND REMAIN BELOW SEASONAL LEVELS AS SOUTH TO SOUTHEAST WINDS PREVAIL.
THE SOUTHERLY WIND DIRECTION WILL CONTRIBUTE TO ROUGH AND CHOPPY SURF
ALONG SOUTH-FACING SHORES, BUT A BIT OF A LULL CAN BE EXPECTED ON
THURSDAY WITH A BRIEF BREAK IN SOUTHERLY WINDS BEFORE THEY
THURSDAY NIGHT. SOUTH SHORE SURF WILL BUILD FURTHER FRIDAY INTO
THE WEEKEND, LIKELY REACHING ADVISORY LEVELS. ONCE SOUTHERLY WINDS
DIMINISH EARLY NEXT WEEK, A SMALL TO MODERATE, LONG-PERIOD SOUTH
SWELL GENERATED BY A GALE FORCE LOW SOUTHEAST OF NEW ZEALAND WILL
ARRIVE ALONG SOUTH-FACING SHORES.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH SATURDAY AFTERNOON FOR ALL ISLANDS.
HIGH WIND WATCH FROM THURSDAY EVENING THROUGH LATE SATURDAY
NIGHT FOR NIIHAU, OAHU, MOLOKAI, LANAI, KAHOOLAWE, AND MAUI.
HIGH WIND WATCH FROM THURSDAY EVENING THROUGH SUNDAY AFTERNOON
FOR BIG ISLAND SUMMITS AND HALEAKALA SUMMIT.
HIGH WIND WATCH FROM FRIDAY MORNING THROUGH LATE SATURDAY NIGHT
FOR BIG ISLAND.
WINTER WEATHER ADVISORY UNTIL 6 PM HST THURSDAY FOR BIG ISLAND
SUMMITS ABOVE 12000 FEET ELEVATION.
WINTER STORM WATCH FROM THURSDAY EVENING THROUGH SATURDAY
AFTERNOON FOR BIG ISLAND SUMMITS ABOVE 12000 FEET ELEVATION.
SHORT TERM UPDATE...BOHLIN
PREVIOUS DISCUSSION...JVC
AVIATION...KINO
MARINE...CQ
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