363
FXHW60 PHFO 111853
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
853 AM HST FRI SEP 11 2026
SYNOPSIS
A DRIER AND LESS HUMID TRADE WIND FLOW WILL CONTINUE TO FILL IN
OVER THE STATE TODAY. SHOWER ACTIVITY WILL BE FOCUSED ACROSS
WINDWARD AREAS AND WILL BECOME LESS FREQUENT, THOUGH LEEWARD BIG
ISLAND MAY STILL EXPERIENCE SCATTERED BRIEFLY HEAVY SHOWERS IN
THE AFTERNOON. A TROPICAL DISTURBANCE MOVING WITHIN THE TRADE
WINDS MAY BRING INCREASED HUMIDITY AND SHOWERS AGAIN LATE TUESDAY
OR WEDNESDAY.
SHORT TERM UPDATE
A NUMBER OF NOTEWORTHY FEATURES ON INFRARED IMAGERY THIS MORNING. TO
THE NORTHWEST, A DIGGING MID-LEVEL TROUGH HAS TRIGGERED A CONVECTIVE
FLARE-UP AS IT FEASTS ON THE REMNANTS OF LOWELL WHICH ITSELF IS IN
THE LATE STAGES OF ITS BAROCLINIC TRANSFORMATION. THE LINGERING BAND
OF TROPICAL MOISTURE THAT HAS SUPPLIED THE ISLANDS WITH HUMID
CONDITIONS AND SPOTTY AFTERNOON SHOWERS EASED WEST OF THE ISLANDS
OVERNIGHT, AND DEWPOINTS WILL FALL MORE UNIFORMLY INTO THE MID TO
UPPER 60S DURING THE NEXT 24 HOURS AS MODERATE TRADES ADVECT A DRIER
AIRMASS INTO THE AREA. THE DELAYED ARRIVAL OF SAID AIRMASS OVER
LEEWARD BIG ISLAND MEANS TODAY'S AFTERNOON CONVECTION MAY YET
PROVIDE A LOCALIZED THREAT FOR NUISANCE FLOODING OVER DOWNSLOPE
AREAS OF THE NORTH & SOUTH KONA DISTRICTS SIMILAR TO YESTERDAY.
NEAR 05N/150W, OR ABOUT 1000 MILES SSE OF HILO, A DISORGANIZED AREA
OF SHOWERS AND THUNDERSTORMS PERSISTS. NHC OFFERS A 20% CHANCE OF
TROPICAL DEVELOPMENT WITH THIS ACTIVITY AS IT LIFTS TOWARD THE
ISLANDS EARLY NEXT WEEK. REGARDLESS OF THE LOW PROBABILITY OF
DEVELOPMENT, ENHANCED MOISTURE AND A MODEST BOOST IN TRADE WINDS
WILL ACCOMPANY THIS FEATURE AS IT LIFTS OUT OF THE DEEP TROPICS
TOWARD THE ISLANDS EARLY NEXT WEEK. GFS OFFERINGS OF VERY HUMID
CONDITIONS CHARACTERIZED BY MID-70S DEWPOINTS DURING THE MIDDLE OF
NEXT WEEK LOOK APPROPRIATE AND WILL PROVIDE RICH LOW-LEVEL MOISTURE
IN SUPPORT OF ENHANCED TRADE WIND SHOWER COVERAGE.
EYES REMAIN FIXED ON TROPICAL STORM NORBERT, 2000 MILES ESE OF HILO,
AS IT SLOWLY ADVANCES WESTWARD AT 14 MPH. ANY POTENTIAL ARRIVAL IN
THE VICINITY OF THE HAWAIIAN ISLANDS IS AT LEAST 10 DAYS AWAY.
FORECAST UNCERTAINTY IS CHARACTERISTICALLY HIGH AT THAT LEAD TIME
AND IT WILL BE SEVERAL DAYS BEFORE CONFIDENCE IN IMPACTS, OR LACK
THEREOF, IMPROVES.
PREV DISCUSSION
ISSUED AT 328 AM HST FRI SEP 11 2026
A DRIER AIR MASS IS SLOWLY DEVELOPING OVER THE STATE ON MODERATE
TRADE WINDS. THE BULK OF A DIFFUSE BAND OF MOISTURE HAS MOVED WEST
OF THE ISLANDS, BUT SOME MOISTURE REMAINS HUNG UP ON BIG ISLAND
AND KAUAI. OVERNIGHT, GENERALLY LESS THAN A QUARTER OF AN INCH OF
RAINFALL HAS BEEN MEASURED ON WINDWARD AREAS OF THESE ISLANDS,
AND SHOWERS REMAINED RATHER ACTIVE OVER THE SOUTH KONA DISTRICT
OF THE BIG ISLAND. LITTLE RAINFALL OCCURRED ON WINDWARD OAHU AND
MAUI COUNTY OVERNIGHT, AND DRY LEEWARD AREAS OF THESE ISLANDS HAVE
BEEN DRY.
EXPECT A DRIER AND LESS HUMID DAY OVER MOST OF THE ISLAND CHAIN
TODAY. MODERATE TRADE WINDS WILL PUSH THE BULK OF THE DEEPER
MOISTURE WEST OF THE ISLANDS, ALLOWING LEEWARD DEW POINTS TO FALL
INTO THE MID 60S AND BRINGING RELIEF FROM HIGH HUMIDITY OF THE
PAST SEVERAL DAYS. TYPICAL LIGHT TO MODERATE SCATTERED SHOWERS
ARE EXPECTED OVER WINDWARD AREAS, BUT RAINFALL ACCUMULATION WILL
BE LOW. SPOTTY AFTERNOON SHOWERS, SOME BRIEFLY HEAVY CANNOT BE
RULED OUT ON LEEWARD BIG ISLAND AND TO A LESSER DEGREE ON LEEWARD
KAUAI.
MODERATE TRADE WINDS WILL BRING RATHER TYPICAL TRADE WIND WEATHER
THIS WEEKEND THROUGH EARLY NEXT WEEK. A WEAK UPPER-LEVEL TROUGH
WILL LINGER OVER THE AREA, KEEPING MODEST INSTABILITY AND A WEAK
INVERSION OVER THE STATE. AS A RESULT, THERE WILL BE A CHANCE OF A
FEW HEAVY SHOWERS OVER THE KONA SLOPES OF BIG ISLAND EACH
AFTERNOON AND EVENING.
A TROPICAL DISTURBANCE MOVING WITHIN THE TRADE WINDS MAY BRING
INCREASED HUMIDITY AND SHOWERS AGAIN LATE TUESDAY OR WEDNESDAY.
DIFFERENCES IN TIMING AND PLACEMENT OF THIS MOISTURE PERSIST
BETWEEN THE GFS AND ECMWF, WHICH IS KEEPING THE DETAILS ELUSIVE AT
THIS POINT. THIS MOISTURE COULD PERSIST THROUGH THURSDAY OF NEXT
WEEK. BEYOND THAT, THERE IS SIGNIFICANT UNCERTAINTY REGARDING THE
FUTURE LOCATION AND TIMING OF EAST PACIFIC TROPICAL STORM NORBERT,
WHICH MAY BE NEAR THE ISLANDS LATE IN THE WEEK.
AVIATION
MODERATE TRADES WILL PREVAIL TODAY AND USHER IN ISOLATED TO
SCATTERED LIGHT SHOWERS TO WINDWARD AND MOUNTAIN AREAS. THE
GREATEST COVERAGE OF LOW CLOUDS AND SHOWERS IS CONCENTRATED AROUND
THE BIG ISLAND THIS MORNING, WHERE MVFR CONDITIONS ARE EXPECTED.
OTHERWISE, BESIDES IN ANY BRIEF PASSING SHOWERS, VFR CONDITIONS
ARE EXPECTED TO PREVAIL ACROSS THE REMAINING TAF SITES.
AIRMET SIERRA REMAINS IN EFFECT FOR TEMPO MOUNTAIN OBSCURATION ON
THE BIG ISLAND THROUGH THE MORNING.
MARINE
MODERATE TO LOCALLY FRESH NORTHEAST TO EAST TRADE WINDS WILL
CONTINUE THROUGH THE FORECAST PERIOD. A TROPICAL DISTURBANCE
MOVING IN FROM THE TRADE WINDS MAY BRING AN INCREASE OF SHOWERS TO
THE COASTAL WATERS BY NEXT WEEK TUESDAY INTO WEDNESDAY.
SURF ALONG SOUTH FACING SHORES WILL GRADUALLY DECLINE THROUGH THE
WEEKEND AS THE SMALL MEDIUM TO LONG PERIOD ENERGY SLOWLY FADES.
CURRENTLY A LOW IN THE SOUTH PACIFIC NEAR AUSTRALIA AND NEW
ZEALAND WILL BRING THE POTENTIAL FOR A MODERATE LONG PERIOD SWELL
FOR HAWAII LATE NEXT WEEK.
EAST FACING SHORES WILL ALSO REMAIN AT SMALL TO MODERATE THROUGH
THE FORECAST PERIOD DUE TO THE FRESH TO LOCALLY STRONG TRADE
WINDS. FLAT TO TINY SURF ALONG NORTH FACING SHORES IS EXPECTED
THROUGH THE FORECAST PERIOD.
FIRE WEATHER
ISSUED AT 328 AM HST FRI SEP 11 2026
FIRE WEATHER RISK WILL REMAIN LOW THE NEXT SEVERAL DAYS DUE LIGHT
TO MODERATE WINDS AND THE EFFECTS OF RECENT RAINFALL, EVEN AS
AFTERNOON RELATIVE HUMIDITY FALLS BELOW 50 PERCENT OVER MANY
LEEWARD AREAS. INVERSION HEIGHTS ARE EXPECTED TO REMAIN ELEVATED
OR WEAK THROUGH MONDAY.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
SHORT TERM UPDATE...JVC
DISCUSSION...WROE
AVIATION...FARRIS
MARINE...SHIGESATO
FIRE WEATHER...WROE
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