061
FXHW60 PHFO 091945
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
945 AM HST WED SEP 9 2026
SYNOPSIS
LIGHT AND VARIABLE FLOW WILL PERSIST ACROSS THE ISLANDS THIS
MORNING WITH EASTERLY WINDS FILLING IN FOR OAHU SOUTHWARD LATER
TODAY. RESIDUAL MOISTURE STRETCHING SOUTHEAST FROM TROPICAL STORM
LOWELL DOWN TO BIG ISLAND AND PORTIONS OF MAUI COUNTY MAY BRING A
RENEWED THREAT OF HEAVY SHOWERS, WHILE SEA BREEZES TRIGGER SPOTTY
AFTERNOON SHOWERS ACROSS THE REST OF THE STATE. TRADE WINDS WILL
SLOWLY BUILD OVER THE STATE LATE TONIGHT INTO THURSDAY, THOUGH
MOISTURE REMAINS ELEVATED ACROSS MUCH OF THE STATE. DRIER TRADE
WIND WEATHER IS EXPECTED TO DEVELOP THURSDAY NIGHT INTO EARLY NEXT
WEEK.
DISCUSSION
MORNING SATELLITE WATER VAPOR IMAGERY SHOWS DRIER AIR BEGINNING TO
SPREAD SOUTHWARD ACROSS KAUAI AND OAHU, AND A BAND OF REMNANT
MOISTURE FROM TROPICAL STORM LOWELL EXTENDING SOUTHEAST AND THEN
WESTWARD INTO MAUI AND THE BIG ISLAND. THIS BAND OF MOISTURE WITH
PRECIPITABLE WATER (PW) NEAR 2" IS FORECAST TO REMAIN IN PLACE
ACROSS PORTIONS OF MAUI AND THE BIG ISLAND INTO THIS AFTERNOON.
THE ABOVE NORMAL PW AND DIURNAL HEATING WILL AID IN MORE ROBUST
SHOWER ACTIVITY OVER THE BIG ISLAND INTERIOR THIS AFTERNOON.
INSTABILITY REMAINS MARGINAL, BUT ENOUGH TO MAINTAIN A SLIGHT
CHANCE OF THUNDERSTORMS. SIMILAR CONDITIONS ARE EXPECTED OVER
HALEAKALA ON MAUI, BUT CONFIDENCE IS A BIT LOWER. STILL, A FEW
HEAVIER AFTERNOON SHOWERS ARE POSSIBLE, ESPECIALLY OVER THE
SOUTHWEST SLOPES OF HALEAKALA NEAR KULA. THE FLOOD WATCH REMAINS
IN EFFECT THROUGH THIS AFTERNOON FOR THE BIG ISLAND. DIURNALLY
DRIVEN SEA BREEZES COULD BRING LIGHTER SHOWERS TO INTERIOR
REGIONS OF THE REMAINING SMALLER ISLANDS.
BY THURSDAY, LIGHT TO MODERATE TRADES WILL RETURN TO THE ENTIRE
STATE. THE DEEPER MOISTURE, NOW CAUGHT UP IN THE TRADES, MAY
BRING AN ENHANCEMENT TO MAINLY WINDWARD SHOWERS ON ALL ISLANDS.
SOME OF THESE SHOWERS MAY OCCASIONALLY PUSH OVER THE TERRAIN AND
ONTO THE LEEWARD SIDES. ONCE AGAIN, DIURNALLY DRIVEN HEAVIER
SHOWERS ARE FORECAST TO DEVELOP OVER BIG ISLAND'S INTERIOR AND
UPPER SLOPES OF MAUNA KEA AND MAUNA LOA DURING THE AFTERNOON. WITH
PW WILL NOT BE QUITE AS HIGH ON THURSDAY, SO RAINFALL RATES AND
AMOUNTS ARE LIKELY TO BE LOWER.
FRIDAY THROUGH THE WEEKEND, TROUGHING FAR NORTHEAST OF THE STATE
WILL HELP TO EASE TRADES BACK INTO THE LIGHT TO MODERATE RANGE
WITH A MORE TYPICAL TRADE SHOWERS CONCENTRATED ALONG WINDWARD
LOCATIONS IN THE NIGHT TO EARLY MORNING HOURS.
AVIATION
WEAK SOUTHERLY FLOW REMAINS OVER THE ISLANDS WITH NOW TROPICAL
STORM LOWELL NORTH OF THE MAIN HAWAIIAN ISLANDS. LOWELL WILL
CONTINUE TO WEAKEN AND MOVE FURTHER AWAY FROM THE ISLANDS. THE
SOUTHERLY FLOW WILL REMAIN IN PLACE FOR MUCH OF TODAY, BUT EXPECT
TRADES TO SLOWLY FILTER BACK IN TONIGHT AND TOMORROW FROM EAST TO
WEST.
MOISTURE BEING PULLED NORTH FROM TROPICAL STORM LOWELL,
PARTICULARLY OVER KAUAI, MAUI, AND THE BIG ISLAND IS CAUSING
CLOUDS, LINGERING SHOWERS, AND SOME MOUNTAIN OBSCURATION. THESE
ISLANDS ARE EXPERIENCED PERIODS OF MVFR CONDITIONS, AND AS SUCH,
AIRMET SIERRA FOR MOUNTAIN OBSCURATION REMAINS IN EFFECT. WITH
LIGHT WINDS AND EXPECTED SEA BREEZE, SHOULD SEE ADDITIONAL CLOUDS
AND SHOWERS DEVELOP THIS AFTERNOON AND EVENING, LEADING TO MORE
MOUNTAIN OBSCURATION. SATELLITE DERIVED PRECIPITABLE WATER
SUGGESTS THAT THESE CLOUDS AND SHOWERS WILL LIKELY LINGER OVER
MAUI AND THE BIG ISLAND.
WITH LIGHT SOUTHERLY WINDS EXPECTED, NOT ANTICIPATING ANY AIRMETS
FOR TURBULENCE TODAY.
MARINE
TROPICAL STORM LOWELL IS ABOUT 460 MILES NNW OF LIHUE AND
IS NOW WELL AWAY FROM THE OFFSHORE WATERS. LINGERING MOISTURE FROM
LOWELL WILL CONTINUE TO PRODUCE SOME SCATTERED DOWNPOURS OVER THE
EASTERN HALF OF THE COASTAL AND OFFSHORE WATERS. LIGHT AND
VARIABLE WINDS WILL GRADUALLY TRANSITION TO LIGHT TO MODERATE
EASTERLY TRADE WINDS STARTING THIS EVENING OVER THE EASTERN HALF
OF THE STATE AND SLOWLY SPREADING WESTWARD THROUGH THURSDAY. BY
THURSDAY EVENING, WE SHOULD SEE MODERATE TO LOCALLY FRESH TRADE
WINDS ACROSS THE STATE THROUGH THE WEEKEND.
A MODERATE LONG-PERIOD SOUTH SWELL PEAKED LAST NIGHT, BUT CONTINUES TO
PRODUCE ELEVATE SURF ALONG SOUTH FACING SHORE THIS MORNING. THIS
LONG-PERIOD SOUTH SWELL COMBINED WITH SHORT-PERIOD SOUTHWEST TO WEST
SWELLS FROM LOWELL WILL PRODUCE ADVISORY LEVEL SURF THROUGH TODAY. THE
LONG-PERIOD SOUTH SWELL WILL GRADUALLY FADE THROUGH THE WEEKEND, BY
WHICH POINT SOUTH SHORE SURF IS EXPECTED TO BECOME SMALL.
SURF ALONG EAST FACING SHORES REMAINS ELEVATED FROM A MEDIUM-PERIOD
EAST SWELL GENERATED BY FORMER TROPICAL CYCLONE MARIE. WITH LIGHT
TRADE WINDS, SURF WILL HOVER NEAR SEASONAL AVERAGES THROUGH FRIDAY.
THE EAST SWELL WILL FADE GRADUALLY, ALLOWING SURF TO FALL BELOW
SEASONAL AVERAGES BY THIS WEEKEND. SURF ALONG NORTH FACING SHORES
CONTINUES TO RECEIVE A SMALL BUMP DUE TO LOWELL. THIS SHORT-PERIOD
NORTHWEST SWELL WILL QUICKLY FADE, ALLOWING SURF TO BECOME TINY ALONG
NORTH FACING SHORES ON THURSDAY AS LOWELL WEAKENS AND TRACKS AWAY
FROM THE ISLANDS.
FIRE WEATHER
FIRE WEATHER RISK WILL REMAIN LOW THE NEXT SEVERAL DAYS DUE LIGHT
WINDS AND LINGERING MOISTURE. EXPECT A SLIGHT CHANCE OF
THUNDERSTORMS OVER THE BIG ISLAND THIS AFTERNOON AND POSSIBLY
THURSDAY AFTERNOON. TEMPERATURE INVERSION HEIGHTS ARE EXPECTED TO
REMAIN ELEVATED OR WEAK.
HFO WATCHES/WARNINGS/ADVISORIES
HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR BIG ISLAND
SOUTH-BIG ISLAND SOUTHEAST-EAST HONOLULU-EWA PLAIN-HONOLULU
METRO-KAHOOLAWE-KAUAI SOUTH-KAUAI SOUTHWEST-KOHALA-KONA-LANAI
LEEWARD-LANAI SOUTH-MAUI CENTRAL VALLEY SOUTH-MAUI LEEWARD WEST-
MOLOKAI LEEWARD SOUTH-MOLOKAI SOUTHEAST-MOLOKAI WEST-NIIHAU-
SOUTH HALEAKALA-SOUTH MAUI/UPCOUNTRY-WAIANAE COAST.
FLOOD WATCH UNTIL 6 PM HST THIS EVENING FOR BIG ISLAND EAST-BIG
ISLAND INTERIOR-BIG ISLAND NORTH-BIG ISLAND SOUTH-BIG ISLAND
SOUTHEAST-BIG ISLAND SUMMITS-KOHALA-KONA.
DISCUSSION...SS
AVIATION..PHILLIPS
MARINE...KINO
FIRE WEATHER...SS
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