933
FXHW60 PHFO 140648
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
848 PM HST SUN SEP 13 2026
SYNOPSIS
AN INCREASE OF MOISTURE FROM THE REMNANTS OF NORBERT WILL BRING A
WET TRADE WIND PATTERN FROM LATE WEDNESDAY THROUGH FRIDAY. DEEP
TROPICAL MOISTURE COMBINED WITH SOME INSTABILITY WILL BRING AN
INCREASE OF HEAVY RAIN ESPECIALLY OVER WINDWARD AND MAUKA AREAS.
IMPROVING WEATHER CONDITIONS ARE GENERALLY EXPECTED OVER NEXT
WEEKEND, BUT SOME SCATTERED SHOWERS WILL LIKELY PERSIST.
DISCUSSION
THIS EVENING'S SATELLITE IMAGERY SHOWS A BAND OF MOISTURE EAST OF
THE BIG ISLAND, WHICH WILL BE MOVING EAST TO WEST ACROSS THE
STATE ON MONDAY. 00Z SOUNDINGS FROM LIHUE AND HILO SHOW A STABLE
TRADE WIND INVERSION AT AROUND 6000 TO 7000 FT. WHILE STABLE
CONDITIONS ARE EXPECTED TO PERSIST OVER THE NEXT FEW DAYS, THE
INCREASE OF MOISTURE WILL BRING AN INCREASE OF HUMIDITY AND SOME
LIGHT TO MODERATE SHOWERS OVER WINDWARD AND MOUNTAIN AREAS.
DEWPOINTS ARE EXPECTED TO GET INTO THE 70S BY LATE MONDAY INTO
TUESDAY, WHICH WILL BRING SOME MUGGY WEATHER ACROSS THE STATE.
STARTING WEDNESDAY AND CONTINUING THROUGH FRIDAY, THE WEATHER
PATTERN WILL CHANGE AS THE REMNANTS OF NORBERT MOVES EAST TO WEST
ACROSS THE STATE. DEEP TROPICAL MOISTURE FROM NORBERT COMBINED
WITH A WEAK UPPER LEVEL TROUGH WILL BRING AN INCREASE OF HEAVY
SHOWERS ESPECIALLY BY THURSDAY. WITH TRADES PICKING UP TO MODERATE
TO BREEZY SPEEDS BY LATE WEDNESDAY INTO THURSDAY, THE FOCUS OF THE
HEAVY RAIN WILL BE OVER WINDWARD AND MAUKA AREAS. A FLOOD WATCH
MAY BE WARRANTED ESPECIALLY FOR THURSDAY INTO THURSDAY NIGHT, BUT
WE WILL WAIT TO SEE WHAT THE HIGH RES MODELS SHOW AS WE GET CLOSER
TO THE SECOND HALF OF THE WEEK. SO OVERALL WE ARE EXPECTING A WET,
TRADE WIND PATTERN DURING THE SECOND HALF OF THE WEEK.
OVER THE WEEKEND, WHILE THE BULK OF THE DEEP TROPICAL MOISTURE
SHOULD MOVE WEST OF THE STATE, SOME SHOWERY WEATHER COULD LINGER
THROUGH AT LEAST PARTS OF SATURDAY. BUT GENERALLY IMPROVING
WEATHER CONDITIONS ARE EXPECTED THIS WEEKEND WITH MODERATE TO
BREEZY TRADE WINDS.
AVIATION
THE FORECAST REMAINS ON TRACK AS LIGHTER AND DRIER TRADE WINDS
HOLD OVER THE HAWAIIAN ISLANDS TONIGHT. EXPECTING SHOWER ACTIVITY
TO REMAIN LIMITED TONIGHT INTO TOMORROW THANKS TO THESE WINDS,
WITH THE WINDWARD SIDE OF THE ISLANDS HAVING A 15-40% CHANCE FOR
SHOWERS WHILE THE REST OF THE AREAS REMAIN DRY. TRADE WINDS FOR
TOMORROW LOOK SIMILAR IN STRENGTH, PERHAPS A TOUCH LIGHTER, AND
THAT SHOULD ALLOW FOR SEA BREEZES TO DEVELOP ON THE LEEWARD SIDE
OF THE ISLANDS.
FOR PMDY CONDITIONS LOOK TO REMAIN DRY, THOUGH WE MAY GET A FEW
LOW TO MID LEVEL CLOUDS DUE TO A LOW SITTING NORTH OF THE REGION.
OPTED TO KEEP THE FORECAST DRY FOR THE SITE ON MONDAY, THOUGH THE
ECMWF MODEL SHOWS THE POTENTIAL FOR SOME PASSING SHOWERS MONDAY
AFTERNOON. BOTH THE GFS AND THE ECMWF SHOW SHOWERS LATE MONDAY
INTO TUESDAY, WITH WINDS SHIFTING TO THE NORTH OR NORTHWEST.
FOR NSTU, MODELS SHOW PASSING SHOWERS THROUGH THE TAF CYCLE,
WHICH MAY BRING PERIODS OF MVFR CIGS AND VIS.
CLOUDS HAVE DECREASED OVER KAUAI, SO LIKELY WILL END THE CURRENT
AIRMET IN EFFECT FOR MOUNTAIN OBSCURATION. NO ADDITIONAL AIRMETS
ARE LIKELY, BUT WE'LL CONTINUE TO KEEP AN EYE OUT AT REPORTS AND
WEBCAMS SHOULD THE REACH MOUNTAIN OBSCURATION CRITERIA FOR CLOUDS
AND/OR PRECIP.
MARINE
ISSUED AT 306 PM HST SUN SEP 13 2026
MODERATE TRADES WILL CONTINUE THROUGH THE WEEK BEFORE GRADUALLY
STRENGTHENING THROUGH THE LATTER HALF OF THE WEEK. MOISTURE
ASSOCIATED WITH A WEAK TROUGH MOVING IN ON THE TRADE WIND FLOW MAY
BRING A SLIGHT UPTICK IN SHOWER ACTIVITY TO THE COASTAL WATERS
TUESDAY INTO WEDNESDAY. WHILE THE CURRENT FORECAST HAS TROPICAL
STORM NORBERT DISSIPATING BEFORE IT NEARS THE HAWAIIAN COASTAL
WATERS FROM THE EAST, REMNANT MOISTURE FROM THIS SYSTEM IS
EXPECTED TO ARRIVE POTENTIALLY BY THURSDAY, LIKELY BRINGING MORE
SHOWERS.
SURF ALONG SOUTH-FACING SHORES WILL GRADUALLY DECLINE THROUGH MONDAY
AS THE SMALL, MEDIUM-PERIOD ENERGY SLOWLY FADES. A SERIES OF
LONG-PERIOD SWELLS ARE EXPECTED DURING THE SECOND HALF OF THE
WEEK. THE FIRST PULSE WILL GRADUALLY FILL IN TUESDAY INTO
WEDNESDAY OUT OF THE SOUTHWEST, FOLLOWED BY LARGER SOUTH-SOUTHWEST
SWELLS FRIDAY INTO THE WEEKEND. SURF COULD GET NEAR ADVISORY
THRESHOLDS OVER THE WEEKEND, BUT AT THIS TIME IT LOOKS LIKE IT
WOULD PEAK JUST BELOW ADVISORY THRESHOLDS.
SURF ALONG EAST-FACING SHORES SHOULD SEE AN INCREASE DURING THE
SECOND HALF OF THE WEEK AS THE TRADES STRENGTHEN AND THE REMNANTS
OF NORBERT MOVES THROUGH THE ISLANDS. FLAT TO TINY SURF ALONG
NORTH FACING SHORES IS EXPECTED THROUGH THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 306 PM HST SUN SEP 13 2026
FIRE WEATHER RISK WILL REMAIN LOW THE NEXT SEVERAL DAYS DUE TO
LIGHT TO MODERATE WINDS AND THE EFFECTS OF RECENT RAINFALL.
INVERSION HEIGHTS SHOULD BE 6000 TO 7000 FT THROUGH MONDAY.
MOISTURE INCREASES THU/FRI, AND SHOULD BRING ENOUGH SHOWERS TO
KEEP THINGS RELATIVELY WET.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...KINO
AVIATION...LP
MARINE...FOSTER
FIRE WEATHER...PARKER
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