290
FXHW60 PHFO 060121
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
321 PM HST SAT JUL 5 2025
SYNOPSIS
STABLE AND BREEZY TRADES CONTINUE THROUGH NEXT WEEK WITH PASSING
SHOWERS FOCUSED OVER WINDWARD AND MAUKA AREAS.
DISCUSSION
HIGH STABILITY PREVAILS AS A STRONG INVERSION REMAINS ESTABLISHED
AROUND 6KFT. THE TYPICAL DIURNAL TREND OF CLEARING LOW CLOUDS AND
DIMINISHING SHOWERS WAS SOMEWHAT MUTED YESTERDAY, AND TO A LESSER
EXTENT TODAY, COURTESY OF MOISTURE TRAPPED BENEATH THIS INVERSION
IN ADDITION TO THE PRESENCE OF HIGH CLOUDS WHICH LIMITED CLOUD
TOP WARMING. SUSPECT THIS WILL BE A THEME WITH ANY POCKETS OF
TRADE WIND MOISTURE DURING THE NEXT FEW DAYS AS MID-LEVEL RIDGING
STRENGTHENS AND THE INVERSION FURTHER STRENGTHENS AND LOWERS
THROUGH TUESDAY. THE LOWERING INVERSION AND STRENGTHENING RIDGING
WILL LIKEWISE FAVOR STRONG TRADE WINDS SUNDAY THROUGH TUESDAY. IN
PARTICULAR, LOCAL ACCELERATIONS THROUGH THE WINDIER PORTIONS OF
MAUI COUNTY AND THE BIG ISLAND WILL BE AUGMENTED BY THE LOWERING
INVERSION AND DRY ADVECTION AT THE TOP OF THE BOUNDARY LAYER
PROVIDING MODEST FORCING FOR DESCENT OF THE EXISTING MOMENTUM
FIELD. THIS WILL ENHANCE GUSTINESS/DOWNSLOPE POTENTIAL AND WILL
MAY WARRANT A WIND ADVISORY FOR THOSE AREAS AS EARLY AS SUNDAY
WITH GREATER CONFIDENCE FOR MONDAY AND TUESDAY.
THE INVERSION THEN LIFTS AND WEAKENS SLIGHTLY BY WEDNESDAY AS A BAND
OF DEEPER TRADE WIND MOISTURE ADVANCES THROUGH THE AREA BRINGING A
SLIGHT UPTICK IN CLOUDS AND SHOWERS FOR WINDWARD AND MAUKA ZONES.
COMBINED WITH SLIGHT WEAKENING OF GOVERNING HIGH PRESSURE, THIS WILL
HELP TAKE THE EDGE OFF OF STRONG TRADE WINDS AS THEY WEAKEN SLIGHTLY
FOR THE REMAINDER OF THE WEEK.
AVIATION
STRONG HIGH PRESSURE TO THE NORTH OF THE HAWAIIAN ISLANDS WILL
MAINTAIN FAIRLY STABLE CONDITIONS AND BREEZY EASTERLY TRADE WINDS
ACROSS THE REGION THROUGH THE NEXT SEVERAL DAYS. PASSING SHOWERS
WILL FAVOR WINDWARD AND MOUNTAIN AREAS IN THE OVERNIGHT TO EARLY
MORNING HOURS, BRINGING THE POTENTIAL FOR BRIEF MVFR CONDITIONS.
OTHERWISE, VFR CONDITIONS WILL PREVAIL.
AIRMET TANGO REMAINS IN EFFECT FOR MODERATE LOW-LEVEL TURBULENCE
OVER AND DOWNWIND OF ISLAND TERRAIN. THIS AIRMET WILL LIKELY
PERSIST INTO EARLY NEXT WEEK AS BREEZY TRADE WINDS CONTINUE.
MARINE
HIGH PRESSURE WILL REMAIN ANCHORED FAR NORTH OF THE MAIN HAWAIIAN
ISLANDS FOR THE NEXT SEVERAL DAYS, WHICH WILL SUPPORT FRESH TO
STRONG TRADE WINDS ACROSS THE AREA. AS A RESULT, A SMALL CRAFT
ADVISORY REMAINS IN EFFECT FOR ALL HAWAIIAN COASTAL WATERS UNTIL
EARLY MONDAY, BUT THIS WILL LIKELY NEED TO BE EXTENDED FOR AT
LEAST SOME ZONES AS THE GUSTY TRADES PERSIST INTO EARLY NEXT WEEK.
THE SURFACE HIGH WILL MOVE EASTWARD AND WEAKEN SLIGHTLY DURING
THE SECOND HALF OF THE WEEK, BUT WINDS ARE LIKELY TO REMAIN
LOCALLY BREEZY IN THE TYPICAL WINDIER CHANNELS AND WATERS SOUTH OF
THE BIG ISLAND THROUGHOUT MUCH OF THE NEXT SEVEN DAYS.
SURF ALONG ALL SHORES WILL REMAIN MOSTLY UNCHANGED THROUGH THE
REST OF THE WEEKEND, THOUGH SOUTH SHORE SURF IS EXPECTED TO SLOWLY
DECLINE AS A SOUTH SWELL FADES OVER THE NEXT SEVERAL DAYS. THE
NEXT SMALL, MEDIUM- TO LONG-PERIOD SOUTH SWELL IS EXPECTED TO
ARRIVE LATE TUESDAY THROUGH WEDNESDAY. THIS SWELL MAY BOOST SOUTH-
FACING SHORE SURF HEIGHTS TO NEAR SUMMERTIME AVERAGES AS IT PEAKS
ON WEDNESDAY. IT WILL THEN DECLINE THROUGH THE REST OF NEXT WEEK.
SURF ALONG EAST-FACING SHORES WILL BE ROUGH AND CHOPPY IN
RESPONSE TO THE GUSTY EASTERLY TRADE WINDS.
FIRE WEATHER
MARGINAL FIRE WEATHER CONDITIONS WILL EXIST INTO THE MIDDLE OF
NEXT WEEK AS EASTERLY TRADE WINDS STRENGTHEN, THE INVERSION FALLS
FROM ITS CURRENT HEIGHT OF 6KFT TO AT LEAST 5KFT AND STRENGTHENS,
AND THE RESIDENT AIRMASS TRENDS SLIGHTLY DRIER. THE KBDI WILL
REMAIN A TOUCH BELOW CRITERIA (600) THROUGHOUT THIS TIME LIMITING
THE LIKLIHOOD OF FIRE WEATHER HEADLINES.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR ALL HAWAIIAN
WATERS-
DISCUSSION...JVC
AVIATION...FARRIS
MARINE...VAUGHAN
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