404
FXHW60 PHFO 231359
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
359 AM HST SUN AUG 23 2026
SYNOPSIS
TRADES WILL REMAIN LOCALLY STRONG TODAY AS TROPICAL STORM MOKE
MOVES WESTWARD, SEVERAL HUNDRED MILES SOUTH OF THE ISLANDS. THIS
SYSTEM WILL BEGIN TO DELIVER PERIODS OF RAINFALL TO BIG ISLAND
THIS MORNING, MAUI COUNTY BY THIS AFTERNOON, THEN OAHU AND KAUAI
BY LATE THIS EVENING. THE HEAVIEST AND MOST WIDESPREAD RAINFALL IS
FORECAST ALONG THE WINDWARD AND SOUTHEAST SLOPES OF BIG ISLAND. A
FLOOD WATCH REMAINS IN EFFECT FOR BIG ISLAND THROUGH MONDAY NIGHT.
A WIND ADVISORY IS IN EFFECT FOR PARTS OF BIG ISLAND AND MAUI
COUNTY THROUGH 6 PM HST THIS EVENING. DRIER TRADE WIND WEATHER
RETURNS TUESDAY.
DISCUSSION
LATEST IR SATELLITE LOOP SHOWS DEEP CONVECTION FROM TROPICAL
STORM MOKE FLARING UP ROUGHLY 200 MILES SOUTH SOUTHEAST OF HILO.
LOW LEVEL CLOUDS AND MOISTURE ON THE NORTHERN PERIPHERY OF THE
CYCLONE CAN ALSO BE SEEN RACING WESTWARD TOWARDS BIG ISLAND AT A
STEADY CLIP. RADAR IS PICKING ON THESE BANDS AND DEPICTS
SCATTERED LIGHT TO EMBEDDED MODERATE SHOWER ACTIVITY. RADAR
ESTIMATED RAIN RATES REMAIN UNIMPRESSIVE THOUGH, MAINLY BELOW A
TENTH OF AN INCH AN HOUR. BY EARLY AFTERNOON, THE HIGH RESOLUTION
WRF-ARW, WRF-FV3, AND NAMNEST MODEL GUIDANCE ALL INDICATE A RATHER
STARK INCREASE IN RAINFALL COVERAGE AND INTENSITY ALONG EASTERN
PORTIONS OF BIG ISLAND. IT WILL NOT TAKE A SIGNIFICANT AMOUNT OF
RAIN TO CAUSE FLASH FLOODING DUE TO SATURATED GROUNDS FROM RECENT
HEAVY RAIN FROM TC LALA. THUS, A FLOOD WATCH WILL REMAIN IN EFFECT
FOR BIG ISLAND THROUGH MONDAY AFTERNOON. RAINFALL AMOUNTS FOR THE
EVENT APPEAR IN GOOD ORDER, AS NHC'S TRACK FOR TROPICAL STORM
MOKE BARELY BUDGED FROM THE PREVIOUS ADVISORY PACKAGE. STORM
TOTAL FORECAST FOR WINDWARD AND SOUTHEAST BIG ISLAND REMAINS AT 5
TO 10 INCHES WITH LOCALLY UP TO 15 INCHES, 3 TO 6 INCHES FOR
EASTERN MAUI, AND GENERALLY 1 TO 2 INCHES ELSEWHERE ACROSS THE
ISLAND CHAIN.
LOCALLY STRONG TRADE WINDS PERSISTED OVERNIGHT AS HAWAII REMAINED
SANDWICHED BETWEEN LOW PRESSURE OF TROPICAL STORM MOKE SOUTH OF
THE STATE AND A 1025 MB SURFACE HIGH TO THE NORTHEAST. A WIND
ADVISORY REMAINS IN EFFECT THROUGH THIS EVENING FOR PORTIONS OF
MAUI, MOLOKAI, LANAI, KAHOOLAWE, AND BIG ISLAND. STRONGEST
SUSTAINED WINDS WILL CONTINUE TO OCCUR OVER MOUNTAIN RIDGES, GAPS
AND WHERE WINDS BLOW DOWNSLOPE OFF HIGHER TERRAIN. OBSERVED SPEEDS
IN THESE AREAS HAVE GENERALLY BEEN SUSTAINED 25 TO 35 MPH WITH
GUSTS UP TO 55 MPH. WINDS ACROSS THE RIDGE TOPS OF THE KO'OLAU AND
WAIANAE MOUNTAIN RANGES MAY NEAR ADVISORY CRITERIA LATER TODAY AS
TRADE WIND SHOWERS AND/OR DEEPER MOISTURE BANDS FROM THE
NORTHERN PERIPHERY OF MOKE BEGIN TO ARRIVE. THOSE ZONES WILL BE
LEFT OUT OF THE ADVISORY FOR NOW, BUT MAY HAVE TO BE INCLUDED IF
THE STRONGER WINDS EXPAND FURTHER WEST. TRADE WINDS ACROSS ALL
ISLANDS SHOULD BEGIN TO EASE BACK TO MODERATE BY TONIGHT.
TUESDAY THROUGH THE END OF NEXT WEEK, DRIER AIR WILL MOVE IN FROM
THE EAST, AND TYPICAL TRADE WINDS/SHOWERS SHOULD RETURN.
AVIATION
TROPICAL STORM MOKE LOCATED A COUPLE HUNDRED MILES SOUTH OF THE
BIG ISLAND CONTINUES ON ITS WEST-NORTHWESTWARD TRACK. RAIN BANDS
FROM THE TROPICAL STORM WILL IMPACT WINDWARD BIG ISLAND TODAY,
WHICH WILL BRING MVFR AND PERIODS OF IFR CONDITIONS TO THE AREA.
TRADE WINDS ARE EXPECTED TO BE MODERATE TO LOCALLY STRONG
STATEWIDE. OUTSIDE OF WINDWARD BIG ISLAND, SHOWERS EMBEDDED
WITHIN THE TRADE WIND FLOW WILL PRIMARILY IMPACT WINDWARD AND
MOUNTAIN AREAS, BRINGING PERIODS OF MVFR CONDITIONS. OTHERWISE,
VFR WILL PREVAIL.
AIRMET TANGO IS IN EFFECT FOR LOW LEVEL TURBULENCE DOWNWIND OF
TERRAIN DUE TO THE STRENGTHENED TRADE WINDS. AIRMET SIERRA IS IN
EFFECT FOR MOUNTAIN OBSCURATIONS OVER WINDWARD BIG ISLAND, AND
WILL LIKELY REMAIN THROUGH TODAY. AN AIRMET FOR IFR CONDITIONS
OVER PORTIONS OF WINDWARD BIG ISLAND IS ALSO A POSSIBILITY LATER
TODAY.
TC SIGMET SERIES XRAY COVERS TROPICAL STORM MOKE AND ITS
CONVECTION.
MARINE
NORTHEAST WINDS HAVE STRENGTHENED ACROSS THE HAWAIIAN ISLAND
COASTAL WATERS, MAINLY AROUND WINDWARD BIG ISLAND, AS A RESULT OF
TROPICAL STORM (TS) MOKE PASSING WEST ACROSS THE FAR SOUTHERN
OFFSHORE WATERS. AT 3 AM HST, MOKE'S LOW LEVEL CENTER OF
CIRCULATION WAS APPROXIMATELY LOCATED 225 NAUTICAL MILES SOUTH
SOUTHEAST OF SOUTH POINT, BIG ISLAND. A TROPICAL STORM WARNING IS
IN EFFECT FOR THE OFFSHORE WATERS. INTENSE CONVECTION ASSOCIATED
WITH THIS STORM IS FLARING UP NORTH OF ITS CENTER AND WILL IMPACT
THE SOUTHEASTERN OFFSHORE WATERS GENERALLY SOUTH OF 18N TODAY. AN
ALL-WATER SMALL CRAFT ADVISORY (SCA) IS IN EFFECT TO ACCOUNT FOR
FRESH TO LOCALLY STRONG TRADES BETWEEN SURFACE HIGH PRESSURE
LOCATED FAR NORTHEAST OF THE ISLANDS AND TS MOKE. HIGHER WINDS AND
SHORT PERIOD WIND WAVE SWELL GENERATED BY TS MOKE MAY PUSH
SIGNIFICANT SEA HEIGHTS TO 10 FEET OR SLIGHTLY HIGHER ACROSS BIG
ISLAND WINDWARD WATERS TODAY.
EAST-FACING SHORE SURF WILL BUILD TODAY IN RESPONSE TO
STRENGTHENING TRADES. SURF ALONG EAST AND SOUTH-FACING SHORES
WILL BE IMPACTED BY A SHORT PERIOD EAST SOUTHEAST SWELL GENERATED
BY TS MOKE AS WELL AS NORTHEAST WIND WAVE SWELL AS A RESULT OF
THESE STRONGER TRADES. AS MOKE PASSES BY TO THE SOUTH TODAY AND
MONDAY A MOUNTING SOUTHEAST SWELL WILL VEER AND BECOME SOUTH TO
SOUTHWEST. THIS SMALL, SHORT PERIOD CAPTURED EASTERLY FETCH FROM
TS MOKE MAY PUSH BIG ISLAND EAST SURF TO NEAR ADVISORY LEVELS
LATER TODAY.
SURF ALONG MOST SOUTH-FACING SHORES WILL BE SLIGHTLY BELOW SUMMER
NORMS BUT STILL REMAIN SOMEWHAT ELEVATED DUE TO A LINGERING SMALL,
LONG PERIOD SOUTH SOUTHWEST SWELL. A THREE TO FOUR FOOT, MEDIUM TO
LONG PERIOD SOUTH SWELL IS EXPECTED TO ARRIVE MONDAY AND TUESDAY
WHICH WILL MAINTAIN THESE NEAR SUMMERTIME HEIGHTS.
SMALL, MEDIUM TO LONG PERIOD WEST TO NORTH SWELL ORIGINATING FROM
HURRICANE LALA IS PASSING AROUND NORTH AND WEST-FACING COASTS
TODAY.
FIRE WEATHER
TRADE WINDS WILL REMAIN LOCALLY STRONG TODAY. THE INVERSION WILL
STEADILY WEAKEN AND ERODE AS DEEP MOISTURE ASSOCIATED WITH TS MOKE
MOVES INTO THE AREA TODAY. HEAVY RAIN IS EXPECTED OVER WINDWARD
AND SE FACING SLOPES OF BIG ISLAND THROUGH MONDAY. A TYPICAL
SUMMERTIME TRADE WIND PATTERN WILL RETURN BY TUESDAY.
HFO WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY UNTIL 6 PM HST THIS EVENING FOR LANAI MAUKA-
KAHOOLAWE-MAUI LEEWARD WEST-KOHALA-BIG ISLAND INTERIOR-MOLOKAI
SOUTHEAST-MOLOKAI NORTH-MOLOKAI WEST-MOLOKAI LEEWARD SOUTH-LANAI
WINDWARD-LANAI LEEWARD-MAUI CENTRAL VALLEY NORTH-MAUI CENTRAL
VALLEY SOUTH-WINDWARD HALEAKALA-SOUTH HALEAKALA-BIG ISLAND SOUTH-
BIG ISLAND SOUTHEAST-BIG ISLAND NORTH.
FLOOD WATCH THROUGH MONDAY AFTERNOON FOR BIG ISLAND-
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR ALL
HAWAIIAN WATERS-
DISCUSSION...THOMAS
AVIATION...DT
MARINE...BLOOD
FIRE WEATHER...THOMAS
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page