738
FXHW60 PHFO 111901
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
901 AM HST WED MAR 11 2026
SYNOPSIS
A POWERFUL KONA STORM WILL IMPACT THE STATE THROUGH THIS WEEKEND
RESULTING IN POTENTIAL FLASH FLOODING, DAMAGING WINDS, AND STRONG
TO SEVERE THUNDERSTORMS. IMPACTS WILL GENERALLY BE FELT OVER THE
WESTERN END OF THE STATE FIRST AND THEN SPREAD EAST WITH TIME. THE
PEAK OF THIS EVENT IS FORECAST TO BE FRIDAY AND SATURDAY.
SHORT TERM UPDATE
ISSUED AT 750 AM HST WED MAR 11 2026
EVENT KICKS OFF WITH A RATHER POORLY MODELED BATCH OF INITIAL
RAINFALL THAT DEVELOPED OVERNIGHT WITHIN A WEAKLY FORCED CORRIDOR OF
SSWLY WARM ADVECTION. THIS AREA OF RAINFALL IS CHARACTERIZED BY
UNIFORMLY DISTRIBUTED RAIN RATES OF OF 1"/HR OR LESS EXCEPT WITHIN
EMBEDDED CONVECTIVE ELEMENTS WHERE RATES UP TO 1.5"/HR ARE NOTED.
12-HOUR RAINFALL AMOUNTS THUS FAR RANGE TOP OUT AT 5.81" AT N
WAILUA DITCH ON KAUAI AND SEVERAL GAUGES AROUND 2" ON OAHU WITH A
PEAK VALUE OF 4.51" AT THE POAMOHO GAUGE. RAIN HAS SINCE SPREAD
INTO MAUI COUNTY WHERE SIMILAR VALUES CAN BE EXPECTED THIS MORNING
BEFORE THIS INITIAL WAVE OF FORCING LIFTS OFF TO THE NORTH
LEAVING BEHIND LESS ORGANIZED LIGHT STRATIFORM RAINFALL IN ITS
WAKE.
DESPITE THE ANTICIPATED LULL IN ACTIVITY BY LATE THIS MORNING, AN
UPPER WAVE PIVOTING THROUGH THE AREA AND OUTSTANDING LEFT EXIT JET
WILL PROVIDE STRONG BACKGROUND FORCING FOR THE BALANCE OF THE DAY.
SURFACE CONVERGENCE WILL BE HARD TO COME BY, BUT STRONG FORCING WILL
MAKE THE MOST OF THE WEAKLY STABLE BACKGROUND ENVIRONMENT SUGGESTING
DISORGANIZED POCKETS OF MODERATE TO HEAVY RAIN WILL BE POSSIBLE
THROUGH THE DAY. HOWEVER, WEAKLY CONVERGENT SW FLOW IS OBSERVED
SOUTHWEST OF OAHU AND CONVECTION IS CURRENTLY DEVELOPING ALONG IT.
SW FLOW WILL STEER THIS CONVECTION TOWARD OAHU WITH AN ESTIMATED
ARRIVAL TIME OF LATE MORNING TO AROUND NOON AND WILL LIKELY CARRY
HIGHER RAIN RATES THAN SEEN THIS MORNING. CONVECTION THEN
POTENTIALLY ADVANCES INTO MAUI COUNTY THIS AFTERNOON. THE WIND FIELD
HAS YET TO RAMP UP, SO ANY ASSOCIATED WIND GUSTS ARE EXPECTED TO BE
SUB-SEVERE. KAUAI LIKELY REMAINS IN A RELATIVE LULL FROM NOW THROUGH
LATE TONIGHT, THOUGH PERIODS OF DISORGANIZED CONVECTION CARRYING
ELEVATED RAIN RATES WILL BE POSSIBLE THROUGHOUT THIS TIME.
THE NEXT WAVE OF SHOWERS IN THE SEQUENCE WILL BEGIN TO MATERIALIZE
WELL SOUTH OF KAUAI MIDDAY TODAY UNDER STELLAR UPPER LEVEL JET
SUPPORT AND CONTINUED DYANMIC FORCING ALOFT. SW WINDS WILL LIKEWISE
BEGIN TO STRENGTHEN DURING THIS TIME WITH 35-40KTS MODELED AT 850MB
AND SOUTHERLIES AT THE SURFACE APPROACHING 20KTS BY EARLY THURSDAY
MORNING. 500MB TEMPS FALLING TO AROUND -13C AND 700-500MB LAPSE
RATES APPROACHING 7C/KM OVER THE WESTERN END OF THE STATE BY THE
PREDAWN HOURS THURSDAY SUGGEST POTENTIAL FOR HEAVY RAIN AND
THUNDERSTORMS FOCUSING OVER KAUAI, OAHU OR BOTH BY SUNRISE
THURSDAY, BUT MOST LIKELY LATER IN THE MORNING.
PREV DISCUSSION
A HIGH-IMPACT WEATHER EVENT CONTINUES TO UNFOLD ACROSS THE
HAWAIIAN ISLANDS AS A POWERFUL KONA LOW REMAINS POSITIONED
NORTHWEST OF THE STATE. RADAR IMAGERY EARLY THIS MORNING SHOWS
BANDS OF SHOWERS LIFTING NORTH ACROSS THE STATE, WITH PEAK
RAINFALL RATES RANGING BETWEEN 1 AND 2 INCHES. SEVERAL STREAMS
HAVE ALREADY BECOME ELEVATED FOLLOWING THE OVERNIGHT RAINFALL, AND
FLOODING REMAINS POSSIBLE WHERE HEAVIER SHOWERS PERSIST.
THE LARGER-SCALE PATTERN REMAINS LARGELY UNCHANGED. A BROAD
UPPER-LEVEL LOW NORTHWEST OF THE ISLANDS CONTINUES TO DEEPEN
WHILE AN ASSOCIATED UPPER TROUGH BECOMES INCREASINGLY NEGATIVELY
TILTED AS A STRONG JET STREAK, WITH CORE WINDS OF 100 TO 140 KT
NEAR 250 MB, DIGS SOUTHEASTWARD ALONG ITS WESTERN FLANK. AS THIS
TROUGH AMPLIFIES AND GRADUALLY EXPANDS TOWARD THE ISLANDS THROUGH
MIDWEEK, THE STATE WILL INCREASINGLY FALL BENEATH THE JET STREAK’S
LEFT-EXIT REGION, SUPPORTING ENHANCED DIVERGENCE ALOFT AND
LARGE-SCALE ASCENT ACROSS THE REGION.
AT THE SURFACE, A BROAD AREA OF LOW PRESSURE WILL REMAIN WELL
NORTHWEST OF THE ISLANDS IN RESPONSE TO STRONG UPPER-LEVEL HEIGHT
FALLS. CENTRAL PRESSURES ARE FORECAST TO REMAIN NEAR 990 MB WHILE
MAINTAINING A SOUTHERLY TO SOUTHEASTERLY FLOW ACROSS THE STATE.
THIS FLOW WILL CONTINUE TO TRANSPORT DEEP TROPICAL MOISTURE
NORTHWARD ACROSS THE ISLAND CHAIN, WITH PRECIPITABLE WATER VALUES
REMAINING NEAR OR ABOVE TWO INCHES.
THE COMBINATION OF STRONG UPPER-LEVEL FORCING, DEEP MOISTURE, AND
PERSISTENT SOUTHERLY FLOW WILL SUPPORT REPEATED ROUNDS OF SHOWERS
AND THUNDERSTORMS THROUGH THE REMAINDER OF THE WEEK. SMALLER
DISTURBANCES ROTATING THROUGH THE UPPER TROUGH WILL LIKELY HELP
FOCUS ADDITIONAL RAINBANDS ACROSS PORTIONS OF THE STATE, RAISING
THE POTENTIAL FOR TRAINING RAINFALL AND LOCALLY INTENSE RAINFALL
RATES, PARTICULARLY IN TERRAIN-FAVORED AREAS.
IN ADDITION TO THE RAINFALL THREAT, STRENGTHENING SOUTH TO
SOUTHWEST WINDS MAY DEVELOP FRIDAY INTO THE WEEKEND AS THE
PRESSURE GRADIENT TIGHTENS BETWEEN THE DEVELOPING LOW TO THE
NORTHWEST AND HIGH PRESSURE TO THE NORTHEAST. IF THIS
MATERIALIZES, STRONG AND POTENTIALLY DAMAGING KONA WINDS WILL BE
POSSIBLE, INCLUDING LOCALIZED DOWNSLOPE WINDS CAPABLE OF DOWNING
TREES AND POWER LINES.
ENVIRONMENTAL CONDITIONS WILL ALSO PERIODICALLY BECOME FAVORABLE
FOR STRONG TO SEVERE THUNDERSTORMS OVER THE NEXT FEW DAYS,
PARTICULARLY FRIDAY INTO SATURDAY. INSTABILITY COMBINED WITH
STRONG DEEP-LAYER WIND SHEAR DURING THIS PERIOD WILL SUPPORT
THUNDERSTORMS CAPABLE OF PRODUCING DAMAGING WINDS, LARGE HAIL, AND
POSSIBLY A TORNADO.
FOR THE SUMMITS OF THE BIG ISLAND, COLDER AIR ASSOCIATED WITH THE
UPPER TROUGH WILL PERIODS OF HEAVY SNOW WITH SIGNIFICANT
ACCUMULATIONS LATER THIS WEEK AND INTO THE WEEKEND, WHICH HAS
PROMPTED THE ISSUANCE OF A WINTER STORM WATCH THIS MORNING.
AVIATION
ISSUED AT 826 AM HST WED MAR 11 2026
MODERATE TO HEAVY SHOWERS WILL PERSIST THROUGH MUCH OF THE DAY
TODAY ACROSS THE STATE WITH PROLONGED PERIODS OF MVFR CONDITIONS
WITH TEMPO IFR/LIFR CONDITIONS AT TIMES UNDER HEAVIER SHOWERS.
INCREASING INSTABILITY TODAY MAY ALLOW FOR ISOLATED THUNDERSTORMS
TO DEVELOP, BUT CONFIDENCE WAS NOT HIGH ENOUGH TO MENTION TS
SPECIFICALLY IN ANY OF THE TAFS.
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.
AIRMET ZULU REMAINS IN EFFECT FOR LIGHT ICING FROM KAUAI THROUGH
MAUI COUNTY FOR FL 130-240.
AIRMET TANGO IS IN EFFECT FOR MODERATE TURBULENCE OVER KAUAI AND
OAHU AS THE VAD WIND PROFILE SHOWS STRONG SOUTHERLY WINDS HAVE
SPREAD ACROSS THE AREA.
AIRMET TANGO IS ALSO IN EFFECT ACROSS THE STATE FOR MODERATE
TURBULENCE ASSOCIATED WITH THIS KONA LOW. UPPER LEVEL TURBULENCE
IS GENERALLY EXPECTED TO DECREASE TOWARDS THE EVENING WITH THE
EXCEPTION OF AREAS WITH THUNDERSTORMS.
MARINE
A POWERFUL KONA STORM WILL RESULT IN HEAVY RAIN, THUNDERSTORMS,
AND ROUGH SEAS TO THE ISLANDS AND ADJACENT COASTAL WATERS THROUGH
THE REST OF THIS WEEK. EARLY THIS MORNING, BANDS OF HEAVY
RAINFALL ARE OBSERVED ON RADAR IMAGERY MOVING FROM SOUTH TO NORTH
WITHIN A SOUTHERLY WIND REGIME ACROSS THE HAWAIIAN WATERS,
ESPECIALLY ACROSS LEEWARD WATERS. FRESH TO LOCALLY STRONG
SOUTHERLY WINDS WERE OBSERVED IN A LATE EVENING ADVANCED
SCATTEROMETER PASS, AND THIS FRESH TO LOCALLY STRONG SOUTHERLY
FLOW WILL CONTINUE THROUGH THE DAY TODAY. A SMALL CRAFT ADVISORY
(SCA) REMAINS IN EFFECT FOR THE WATERS SURROUNDING KAUAI, AND BOTH
LEEWARD AND WINDWARD WATERS OF THE BIG ISLAND HAVE ALSO BEEN
ADDED TO THE SCA WITH THIS MORNING'S UPDATES BASED ON THE LATEST
ASCAT PASS AND HI-RES MODEL GUIDANCE. AFTER A BRIEF LULL IN
SOUTHERLY WIND SPEEDS TONIGHT INTO THURSDAY, REINTENSIFICATION
WILL CAUSE WINDS TO APPROACH, OR POSSIBLY REACH, GALE-FORCE SPEEDS
FOR PORTIONS OF THE AREA AS EARLY AS THURSDAY NIGHT OR FRIDAY,
AND LASTING INTO THE WEEKEND.
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. THE FIRST OF THESE WILL PEAK TODAY, RESULTING
IN A SLIGHT BUMP IN SURF ALONG NORTH AND WEST-FACING SHORES. THIS
SWELL WILL THEN DECLINE BEFORE THE NEXT WEST-NORTHWEST SWELL
ARRIVES ON FRIDAY. ADDITIONALLY, A SMALL, MEDIUM- PERIOD NORTH
SWELL IS ALSO EXPECTED TO ARRIVE THURSDAY NIGHT INTO FRIDAY.
CHOPPY SURF ALONG EAST-FACING SHORES WILL CONTINUE TO TREND DOWNWARD,
FALLING BELOW SEASONAL LEVELS TODAY AS WINDS VEER SOUTHERLY. WITH
THE SHIFT OF WIND DIRECTION, SURF ALONG SOUTH-FACING SHORES WILL
INCREASE, BECOMING ROUGH AND CHOPPY. LATER THIS WEEK, ANOTHER
ROUND OF STRONGER SOUTHERLY WINDS FRIDAY INTO THE WEEKEND WILL
CAUSE SOUTH SHORE SURF TO BUILD FURTHER, LIKELY REACHING ADVISORY
LEVELS. A SERIES OF SMALL, LONG-PERIOD SOUTH SWELLS WILL ALSO
MOVE THROUGH.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH SATURDAY AFTERNOON FOR CENTRAL OAHU-EAST
HONOLULU-EWA PLAIN-HALEAKALA SUMMIT-HONOLULU METRO-KAHOOLAWE-
KAUAI EAST-KAUAI MOUNTAINS-KAUAI NORTH-KAUAI SOUTH-KAUAI
SOUTHWEST-KIPAHULU-KOOLAU LEEWARD-KOOLAU WINDWARD-LANAI LEEWARD-
LANAI MAUKA-LANAI SOUTH-LANAI WINDWARD-MAUI CENTRAL VALLEY NORTH-
MAUI CENTRAL VALLEY SOUTH-MAUI LEEWARD WEST-MAUI WINDWARD WEST-
MOLOKAI LEEWARD SOUTH-MOLOKAI NORTH-MOLOKAI SOUTHEAST-MOLOKAI
WEST-MOLOKAI WINDWARD-NIIHAU-OAHU NORTH SHORE-OLOMANA-SOUTH
HALEAKALA-SOUTH MAUI/UPCOUNTRY-WAIANAE COAST-WAIANAE MOUNTAINS-
WINDWARD HALEAKALA.
HIGH WIND WATCH FROM THURSDAY EVENING THROUGH SUNDAY AFTERNOON
FOR BIG ISLAND SUMMITS-HALEAKALA SUMMIT.
FLOOD WATCH FROM 6 PM HST THIS EVENING THROUGH SATURDAY
AFTERNOON FOR BIG ISLAND EAST-BIG ISLAND INTERIOR-BIG ISLAND
NORTH-BIG ISLAND SOUTH-BIG ISLAND SOUTHEAST-KOHALA-KONA.
WINTER STORM WATCH FROM THURSDAY EVENING THROUGH SATURDAY
AFTERNOON FOR BIG ISLAND SUMMITS.
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR BIG ISLAND
LEEWARD WATERS-BIG ISLAND WINDWARD WATERS-KAUAI CHANNEL-KAUAI
LEEWARD WATERS-KAUAI NORTHWEST WATERS-KAUAI WINDWARD WATERS.
SHORT TERM UPDATE...JVC
DISCUSSION...GIBBS
AVIATION...EVANS
MARINE...VAUGHAN
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