193
FXHW60 PHFO 040128
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
328 PM HST THU JUL 3 2025
SYNOPSIS
STABLE TRADE WINDS WILL INCREASE LATE FRIDAY AND WILL BE BREEZY
AND GUSTY SATURDAY THROUGH AT LEAST TUESDAY. MODEST SHOWERS WILL
BE FOCUSED ALONG WINDWARD SLOPES, AND ASIDE FROM AFTERNOON SHOWERS
OVER THE KONA SLOPES OF THE BIG ISLAND, LEEWARD AREAS WILL BE
MOSTLY DRY.
DISCUSSION
TYPICAL EARLY SUMMER CONDITIONS ARE IN PLACE. BROAD SURFACE HIGH
PRESSURE NORTH OF THE STATE IS DRIVING MODERATE TO LOCALLY BREEZY
TRADE WINDS, AND MID LEVEL RIDGING IS PRODUCING AN INVERSION BASED
BETWEEN 6,500 AND 7,500 FEET. PRECIPITABLE WATER IS RUNNING NEAR
TO JUST BELOW SEASONAL NORMAL, AND LITTLE ORGANIZED MOISTURE IS
OBSERVED IN THE TRADE WIND FLOW. AS A RESULT, RAINFALL HAS BEEN
MODEST AND FOCUSED OVER WINDWARD SLOPES, WHERE LESS THAN A HALF
OF AN INCH HAS BEEN MEASURED DURING THE PAST 24 HOURS, AND MOST
LEEWARD AREAS HAVE BEEN DRY. THE ONLY EXCEPTIONS ARE THE KONA
SLOPES OF THE BIG ISLAND AND PORTIONS OF UPCOUNTRY MAUI, WHERE
SPOTTY AFTERNOON SHOWERS WILL TAPER OFF LATER IN THE EVENING.
LITTLE CHANGE IS EXPECTED INTO INDEPENDENCE DAY.
TRADE WINDS WILL BECOME BREEZY ON SATURDAY, AND THE STABLE, GUSTY
AND RATHER DRY CONDITIONS WILL PERSIST THROUGH AT LEAST TUESDAY.
TRADES WILL INCREASE AS SURFACE HIGH PRESSURE FAR NORTHEAST OF
HAWAII STRENGTHENS TO AROUND 1032 MB. A MID LEVEL RIDGE WILL BUILD
OVERHEAD AND PUSH THE INVERSION DOWN TO 5,000 TO 6,500 FEET. THE
INTERACTION OF THE BREEZY TRADE WIND FLOW WITH THE ISLANDS SHOULD
GENERATE WIND GUSTS AROUND 40 MPH OVER AND DOWNWIND OF TERRAIN,
THOUGH ISOLATED AREAS ON THE BIG ISLAND AND MAUI COUNTY COULD
APPROACH WIND ADVISORY CRITERIA AT TIMES. THE GFS AND ECMWF ARE
SHOWING NO DISTINCT ORGANIZED AREAS OF MOISTURE WITH PRECIPITABLE
WATER BELOW SEASONAL AVERAGE. THIS SHOULD RESULT IN MODEST
WINDWARD RAINFALL AND ASIDE FROM SCATTERED AFTERNOON AND EVENING
SHOWERS ON THE KONA SLOPES OF THE BIG ISLAND, DRY LEEWARD
CONDITIONS. SEE THE FIRE WEATHER SECTION BELOW FOR ADDITIONAL
DISCUSSION. A SLIGHT DECREASE IN TRADE WINDS IS EXPECTED
WEDNESDAY.
AVIATION
MODERATE TO LOCALLY BREEZY TRADE WINDS WILL PREVAIL ACROSS THE
ISLAND CHAIN FOR THE NEXT SEVERAL DAYS. LOW CLOUDS AND SHOWERS
WILL FOCUS MAINLY ALONG WINDWARD AND MOUNTAIN AREAS, THOUGH SOME
ISOLATED SHOWERS COULD SPILL OVER INTO LEEWARD AREAS FROM TIME TO
TIME. MVFR CEILINGS AND VISIBILITIES WILL BE POSSIBLE WITHIN ANY
PASSING SHOWERS, BUT VFR FLIGHT CONDITIONS WILL GENERALLY PREVAIL
AT MOST LOCATIONS THROUGHOUT THE NEXT FEW DAYS.
AIRMET TANGO HAS BEEN ISSUED TODAY FOR MODERATE LOW-LEVEL
TURBULENCE OVER AND DOWNWIND OF ISLAND TERRAIN. THIS AIRMET WILL
LIKELY PERSIST INTO THE WEEKEND AS BREEZY TRADES CONTINUE.
MARINE
HIGH PRESSURE RESTRENGTHENS AND ESTABLISHES NORTH OF THE ISLANDS
CAUSING STRONG TRADES TO DEVELOP THIS WEEKEND. THE EXISTING SMALL
CRAFT ADVISORY HAS BEEN EXTENDED THROUGH THE WEEKEND AND WILL
REQUIRE FURTHER EXPANSION IN AREAL COVERAGE NEXT WEEK.
EXISTING S SWELL DECLINES THROUGH THE WEEKEND CAUSING SURF TO
FALL BELOW THE SUMMERTIME AVERAGE. TINY, LONG PERIOD S SWELL THEN
HOLDS INTO NEXT WEEK AS BELOW AVERAGE SURF CONTINUES. WIND WAVES
AND SHORT PERIOD FRESH SWELL WILL BECOME MORE PROMINENT AS TRADES
STRENGTHEN THIS WEEKEND INTO NEXT WEEK. N SHORE REMAINS TINY.
FIRE WEATHER
BREEZY, GUSTY, AND RATHER DRY CONDITIONS WILL DEVELOP ON SATURDAY
AND PERSIST INTO EARLY NEXT WEEK. RELATIVE HUMIDITY AT LOWER
LEEWARD ELEVATIONS WILL LIKELY FALL BELOW 45 PERCENT EACH
AFTERNOON, AND WITH THE INVERSION DROPPING TO AS LOW AS 5,000
FEET WINDS WILL BECOME GUSTY OVER AND DOWNWIND OF TERRAIN. THIS
WILL RESULT IN NEAR CRITICAL FIRE WEATHER CONDITIONS OVER DRY
LEEWARD AREAS, THOUGH NO HEADLINES (WATCHES OR WARNINGS) ARE DUE
SINCE THE KEETCH BYRAM DROUGHT INDEX WILL REMAIN BELOW THE 600
THRESHOLD AT HONOLULU.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST SUNDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...WROE
AVIATION...VAUGHAN
MARINE...JVC
FIRE WEATHER...WROE
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