019
FXHW60 PHFO 010136
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
336 PM HST MON AUG 31 2026
SYNOPSIS
BREEZY TRADES WILL CONTINUE IN WEDNESDAY WITH SHOWERS GENERALLY
FAVORING WINDWARD AND MAUKA AREAS, PARTICULARLY DURING THE
OVERNIGHT THROUGH EARLY MORNING HOURS EACH DAY. TROPICAL STORM
LOWELL IS NEARLY 700 MILES ESE OF THE BIG ISLAND. LATEST FORECAST
TRACK HAS LOWELL PASSING SOUTH OF THE BIG ISLAND LATE WEDNESDAY
INTO THURSDAY. TRADE WINDS ARE EXPECTED TO BECOME STRONG AND GUSTY
AS EARLY AS WEDNESDAY AFTERNOON INTO FRIDAY AS LOWELL PASSES
SOUTH OF THE STATE. FORECAST STILL REMAINS VERY UNCERTAIN FOR
LABOR DAY WEEKEND, WITH THE POTENTIAL FOR LOWELL AND KARINA WITHIN
THE VICINITY OF THE STATE.
DISCUSSION
SATELLITE AND RADAR IMAGERY SHOW ISOLATED PASSING CLOUDS AND
SHOWERS MAINLY OVER THE WINDWARD AND MAUKA AREAS. EXPECT CHANCES
OF SHOWERS TO INCREASE TONIGHT AS A BAND OF SHOWERS MOVES EAST TO
WEST ACROSS THE STATE. OUTER RAINBANDS AND MOISTURE FIELD FROM
TROPICAL STORM LOWELL WILL BEGIN TO FILL IN DURING THE DAY
TUESDAY, INCREASING CHANCES OF PASSING TRADE WIND SHOWERS AND
DEWPOINT TEMPERATURE ABOVE 70 DEGREES. TRADE WINDS WILL STAY
BREEZY DUE TO A STRONG SURFACE HIGH REMAINING FAR NORTH OF THE
AREA. OVERALL EXPECT AN UP TICK IN PASSING SHOWERS RIDING IN WITH
THE BREEZY TRADES OVER THE NEXT FEW DAYS, ESPECIALLY TUESDAY
NIGHT AS A SMALL INVERTED TROUGH, CURRENTLY ALONG 145W LATITUDE,
MOVES OVER THE STATE.
LATEST FORECAST FROM THE NATIONAL HURRICANE CENTER (NHC) HAS
LOWELL PASSING A LITTLE OVER 300 MILES SOUTH OF THE BIG ISLAND
WEDNESDAY NIGHT INTO THURSDAY AS A CAT 3 MAJOR HURRICANE. WHILE
PROBABILITIES FOR TROPICAL STORM FORCE WINDS REMAIN LOW OVER THE
STATE, THE TIGHTENING OF THE PRESSURE GRADIENT OVER THE ISLANDS
WILL LIKELY PRODUCE VERY WINDY AND GUSTY TRADE WIND WEATHER AS
EARLY AS WEDNESDAY AFTERNOON THROUGH FRIDAY. WINDS COULD REACH
ADVISORY THRESHOLDS WITH WIND GUSTS OVER 50 MPH POSSIBLE DURING
THIS TIME. AS FAR AS RAINFALL, THE BULK OF THE MOISTURE WILL
LIKELY PASS SOUTH OF THE STATE. SOME OF THE OUTER RAINBANDS,
ESPECIALLY ON THE TAIL END OF LOWELL AND THE BEGINNING OF KARINA
COULD BRING IN SOME ENHANCED TRADE WIND SHOWERS AROUND FRIDAY OR
SATURDAY.
THE FORECAST SPREAD DRASTICALLY INCREASES OVER LABOR DAY WEEKEND
INTO EARLY NEXT WEEK AS AN UPPER LEVEL TROUGH/LOW DEVELOPS NORTH
OF THE STATE. LATEST 12Z RUN OF THE GOOGLE DEEPMIND (GDM) MODEL
CONTINUES TO SHOWS LOWELL TAKING SHARP NORTHWARD TURN OVER THE
WEEKEND. WHILE CONFIDENCE HAS INCREASED ON LOWELL PASSING SOUTH
OF THE STATE DURING THE WEEK, THE FORECAST STILL REMAINS VERY
UNCERTAIN OVER LABOR DAY WEEKEND INTO EARLY NEXT WITH SEVERAL
ENSEMBLE MEMBERS OF THE GDM SHOWING A SHARP NORTHWARD TURN. ALSO
DURING THIS TIME, WE COULD SEE KARINA WITHIN THE VICINITY OF THE
ISLANDS LATE THIS WEEKEND. PLEASE KEEP AN EYE OUT ON THE
HURRICANES.GOV PAGE FOR THE OFFICIAL NHC FORECAST FOR LOWELL AND
KARINA.
AVIATION
A STRONG HIGH PRESSURE SYSTEM FAR NORTH OF THE HAWAIIAN ISLANDS
WILL MAINTAIN MODERATE TO BREEZY TRADE WINDS ACROSS THE REGION
THROUGH AT LEAST TUESDAY. CLOUDS AND SHOWERS WILL GENERALLY FAVOR
WINDWARD AND MOUNTAIN AREAS THROUGH THIS PERIOD AS MOISTURE MOVES
IN ON THE TRADES, BRINGING BRIEF PERIODS OF MVFR CONDITIONS.
OTHERWISE, VFR CONDITIONS WILL PREVAIL. TRADE WIND SPEEDS ARE
EXPECTED TO INCREASE OVER THE LATTER HALF OF THE WEEK AS THE
PRESSURE GRADIENT BETWEEN TROPICAL CYCLONE LOWELL PASSING SOUTH OF
THE STATE AND THE HIGH TO THE FAR NORTH STRENGTHENS.
AIRMET SIERRA IS IN EFFECT FOR TEMPO MOUNTAIN OBSCURATIONS FOR
NORTH THROUGH EAST SECTIONS OF KAUAI, MAUI AND THE BIG ISLAND DUE
TO PERSISTENT LOW CLOUD AND SHOWER COVERAGE. THIS AIRMET WILL
LIKELY BE NEEDED THROUGH THE AFTERNOON, AND POSSIBLY THROUGH
TONIGHT FOR THE EASTERN END OF THE STATE.
AIRMET TANGO REMAINS IN EFFECT FOR MODERATE LOW LEVEL TURBULENCE
SOUTH THROUGH WEST OF ISLAND MOUNTAINS. THIS TURBULENCE AIRMET
WILL LIKELY CONTINUE FOR THE FORESEEABLE FUTURE.
MARINE
A STRONG SURFACE HIGH WILL REMAIN NEARLY STATIONARY FAR NORTH OF
THE HAWAIIAN ISLANDS THIS WEEK, KEEPING MODERATE TO LOCALLY
STRONG TRADE WINDS IN PLACE. TROPICAL STORM LOWELL, NOW IN THE
CENTRAL PACIFIC, IS FORECAST TO INTENSIFY INTO A HURRICANE TONIGHT
AND WILL TRACK VERY CLOSE TO OR MOVE INTO THE SOUTHERN OFFSHORE
WATERS, BRINGING POSSIBLE HURRICANE CONDITIONS FROM WEDNESDAY
INTO THURSDAY. THERE IS STILL SOME UNCERTAINTY WITH THE FORECAST
TRACK OF LOWELL, ESPECIALLY CLOSER TO THIS WEEKEND AS THE CYCLONE
BEGINS TO GAIN LATITUDE, WHICH WILL HAVE SIGNIFICANT IMPACTS ON
THE WIND, WAVE, AND SURF FORECAST FOR THE REGION. REGARDLESS OF
LOWELL'S FINAL PATH, TRADE WINDS WILL INCREASE BY WEDNESDAY
AFTERNOON THROUGH FRIDAY AS A RESULT OF THE GRADIENT BETWEEN HIGH
PRESSURE TO THE NORTH, AND LOWELL TO THE SOUTH. BY THIS WEEKEND,
HURRICANE KARINA, APPROACHING THE REGION FROM THE EAST, WILL
INCREASINGLY BE A FACTOR IN THE FORECAST OF SEAS AND SURF AS WELL.
A SMALL LONG PERIOD SOUTH SWELL WILL HOLD THROUGH TONIGHT BEFORE A
MODERATE SOUTH SWELL ARRIVES ON TUESDAY. THIS SWELL WILL BUILD
TUESDAY MORNING AND THEN PEAK ON WEDNESDAY, BRINGING SURF HEIGHTS
TO JUST BELOW ADVISORY THRESHOLDS. THIS SWELL WILL THEN GRADUALLY
DECLINE THROUGH THE REST OF THE WEEK, WHILE AT THE SAME TIME,
MEDIUM PERIOD ENERGY FROM LOWELL COULD START FILLING IN ACROSS
SOUTH AND SOUTHEAST SHORES. SWELL FROM LOWELL COULD PEAK THIS
WEEKEND, AND ITS SIZE WILL BE HIGHLY DEPENDENT ON THE TRACK AND
INTENSITY OF THE STORM. CURRENTLY THE SWELL FROM LOWELL, BASED ON
ITS CURRENT FORECAST, IS ESTIMATED TO ELEVATE SURF BUT STAY BELOW
ADVISORY LEVELS.
TRADE WIND SWELL ENERGY WILL KEEP ELEVATED SURF HEIGHTS ALONG ALL
EAST FACING SHORES THROUGH THE COMING WEEK. LATER IN THE WEEK, A
MEDIUM-PERIOD EAST SWELL ARRIVES FROM HURRICANE KARINA THAT COULD
PUSH EAST SHORE SURF TO ADVISORY THRESHOLDS BY THIS WEEKEND INTO
NEXT WEEK.
FIRE WEATHER
BREEZY TRADES CONTINUE THROUGH TUESDAY AND THEN COULD STRENGTHEN
AS EARLY AS WEDNESDAY AFTERNOON THROUGH FRIDAY AS TC LOWELL
PASSES SOUTH OF THE ISLANDS. STRONG GUSTY WINDS OVER 50 MPH WILL
BE POSSIBLE ACROSS SELECT AREAS DURING THIS TIME. WHILE FUEL
CONDITIONS ARE NOT AT CRITICAL LEVELS DUE TO ABUNDANT RAINFALL WE
HAVE RECEIVED OVER THE PAST SEVERAL WEEKS, MODERATE FIRE DANGER
WILL BE POSSIBLE FOR AREAS MAINLY DUE TO VERY WINDY CONDITIONS.
DEWPOINTS ARE EXPECTED TO INCREASE IN THE UPPER 60S AND LOW 70S
BY TUESDAY AFTERNOON AND HOLD THROUGH THE WEEK, KEEPING MINIMUM
HUMIDITIES IN THE 50S FOR THE MOST PART. A FEW LEEWARD AREAS COULD
STILL SEE HUMIDITIES DOWN INTO THE MID 40S ESPECIALLY ON THURSDAY
AS A POCKET OF DRY AIR MOVES IN. THE EXACT TRACK OF TC LOWELL
REMAINS UNCERTAIN AND THUS POTENTIAL FOR MEANINGFUL RAINFALL
REMAINS UNCERTAIN AT THIS TIME. THE INVERSION WILL HOVER BETWEEN
5500 FT AND 6500 FT THE NEXT COUPLE OF DAYS.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST TUESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...ALMANZA
AVIATION...FARRIS
MARINE...TSAMOUS
FIRE WEATHER...ALMANZA
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