627
FXHW60 PHFO 181353
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
353 AM HST MON AUG 18 2025
SYNOPSIS
BREEZY TRADE WINDS WILL GRADUALLY RETURN TODAY AS WEAK TROUGH
MOVES WEST OF THE STATE TONIGHT. ISOLATED TO SCATTERED CLOUDS AND
SHOWERS WILL PERSIST THROUGH THE MORNING HOURS MAINLY ALONG
WINDWARD AND MAUKA REGIONS WITH FEW SHOWERS SPILLING OVER THE
LEEWARD AREAS AT TIMES. A GRADUAL DRYING TREND IS EXPECTED TONIGHT
INTO TUESDAY WITH TYPICAL SUMMER TIME TRADE WIND WEATHER (STABLE
AND MOSTLY DRY CONDITIONS) EXPECTED DURING THE SECOND HALF OF
WEEK.
DISCUSSION
A WEAK SURFACE TROUGH ASSOCIATED WITH THE REMNANTS OF FORMER
TROPICAL CYCLONE IVO WILL CONTINUE TO MOVE WEST OVER THE STATE
TODAY, ALLOWING TRADE WIND SPEEDS TO INCREASE THROUGHOUT THE DAY.
THIS MORNING SOUNDING FROM LIHUE SHOWS TRADEWIND INVERSION HEIGHT
AROUND 9 KFT WITH PRECIPITABLE WATER VAPOR VALUES AROUND 1.68
INCHES. SCATTERED, LIGHT TO MODERATE SHOWERS CAN BE SEEN ON THE
RADAR EARLY THIS MORNING, MAINLY FOCUSED OVER WINDWARD AND
MOUNTAIN AREAS WITH SOME SHOWERS SPILLING OVER TO LEEWARD AREAS
AT TIMES. EXPECT SHOWERS TO EASE SLIGHTLY DURING THE DAY AS DRIER AIR
FILTERS IN FROM THE EAST, EXPECT FOR THE KONA SLOPES OF THE BIG
ISLAND, WHICH WILL SEE SOME CLOUDS AND SHOWER DEVELOPMENT THIS
AFTERNOON AS SEABREEZES DEVELOP.
AS THIS TROUGH EXITS THE AREA TONIGHT, WE SHOULD SEE LESS CLOUDS
AND DRIER CONDITIONS ON TUESDAY. TRADE WINDS WILL CONTINUE TO STRENGTHEN
TUESDAY AFTERNOON WITH MODERATE TO LOCALLY BREEZY TRADES EXPECTED
THROUGHOUT THE REST OF THE WEEK. TYPICAL SUMMER TIME TRADE WIND
WEATHER IS EXPECTED THROUGHOUT THE SECOND HALF OF THE WEEK WITH
STABLE AND MOSTLY DRY CONDITIONS. SUBTLE INCREASES OF MOISTURE
WILL BRING IN SOME WINDWARD SHOWERS AT TIMES WITH MOSTLY DRY
CONDITIONS PERSISTING OVER LEEWARD AREAS. TRADE WINDS COULD
SLIGHTLY STRENGTHEN OVER NEXT WEEKEND.
AVIATION
MODERATE TO LOCALLY BREEZY TRADES WILL PERSIST THROUGH THE
FORECAST PERIOD. LOW CIGS AND SHRA WILL CONTINUE OVER WINDWARD AND
MAUKA AREAS THROUGH THE EARLY MORNING HOURS GENERATING MVFR CONDS
IN SHRA, OTHERWISE VFR PREVAILS.
AIRMET SIERRA HAS BEEN ISSUED FOR MTN OBSC OVERNIGHT DUE TO AN
INCREASE IN LOW CLOUDS AND SHRA ALONG WINDWARD AND MAUKA REGIONS.
CONDS MAY BECOME VFR DURING THE AFTERNOON HOURS HAS INVERSION
HEIGHTS INCREASE AND SHRA DECREASE.
AIRMET TANGO MAY BE NEEDED LATER TODAY AS WIND SPEEDS INCREASE
BELOW THE INVERSION.
MARINE
FRESH TO LOCALLY STRONG TRADES WILL PERSIST THROUGH THE WEEK AS
RIDGING STAYS SITUATED NORTH OF THE STATE. THE SMALL CRAFT
ADVISORY (SCA), FOR THE TYPICAL WINDY WATERS AROUND MAUI AND THE
BIG ISLAND, WILL REMAIN IN EFFECT THROUGH AT LEAST WEDNESDAY
MORNING WITH A LIKELY EXTENSION INTO THE WEEKEND.
THE ONGOING SMALL, MEDIUM PERIOD SOUTH (180-190) SWELL WILL HOLD
THROUGH TOMORROW AND GENERATE WAIST TO NEAR HEAD HIGH SURF WITHIN
HIGHER SETS. A SLIGHTLY LARGER, MEDIUM TO LONG PERIOD, SOUTH
SWELL IS PROGGED TO ARRIVE ON WEDNESDAY, ADDING A LITTLE BUMP TO
SURF HEIGHTS ALONG SOUTH FACING SHORES THROUGH THE REMAINDER OF
THE WORK WEEK.
CHOPPY CONDITIONS WILL CONTINUE FOR EAST-FACING SHORES THROUGH
THE FORECAST PERIOD DUE TO THE PERSISTENT FRESH TRADES. MEANWHILE,
EXPECT SURF TO BE FLAT TO TINY ALONG NORTH FACING SHORES.
FIRE WEATHER
CONDITIONS SHOULD REMAIN BELOW CRITICAL FIRE WEATHER THRESHOLDS
THROUGH THE FIRST HALF OF THIS WEEK. A WEAK LOW-LEVEL TROUGH WILL
CONTINUE TO MOVE ACROSS THE STATE TODAY, BRINGING AN INCREASE IN
HUMIDITY AND SHOWER ACTIVITY AND WEAKENING THE TRADE WIND
INVERSION. 12Z SOUNDING FROM LIHUE SHOWS THE TRADE WIND INVERSION
HAS LIFTED FROM 5000 FEET SUNDAY AFTERNOON TO 9000 FEET EARLY THIS
MORNING. AS THE TROUGH EXITS THE AREA, WE SHOULD SEE THE RETURN
OF STABLE AND DRY CONDITIONS BY TUESDAY AFTERNOON. DURING THE
SECOND HALF OF THE WEEK WE SHOULD SEE STABLE AND DRY CONDITIONS
WITH A STRONGER TRADE WIND INVERSION AT AROUND 5000-6000 FT.
BREEZY TRADES ARE ALSO EXPECTED DURING THIS TIME, WHICH COULD
PRODUCE ELEVATED FIRE WEATHER CONCERNS LATER IN THE WEEK THROUGH
NEXT WEEKEND.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...ALMANZA
AVIATION...ALMANZA
MARINE...THOMAS
FIRE WEATHER...ALMANZA
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