283
FXHW60 PHFO 051339
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
339 AM HST SAT JUL 5 2025
SYNOPSIS
STABLE AND BREEZY TRADE WINDS WILL CONTINUE THROUGH WEDNESDAY AS
A STRONG HIGH PRESSURE RIDGE ANCHORS IN PLACE NORTH OF THE STATE.
BRIEF PASSING SHOWERS WILL FAVOR WINDWARD AND MOUNTAIN SLOPES,
AND LATE AFTERNOON TO EVENING SHOWERS ALONG THE KONA SLOPES OF
THE BIG ISLAND, OTHER LEEWARD AREAS WILL BE MOSTLY DRY.
DISCUSSION
WEATHER CONDITIONS ARE FAIRLY SIMILAR TO WHAT WE SAW 24 HOURS AGO.
FAIRLY STABLE LOW CLOUDS ARE RIDING THE BREEZY EASTERLY TRADE
WINDS AND PRODUCING A FEW SHOWERS OVER WINDWARD ISLAND MOUNTAINS
THIS MORNING. AN UPPER LEVEL RIDGE WILL PRODUCE A FAIRLY STABLE
SUBSIDENCE ACROSS THE HAWAII REGION WITH TEMPERATURE INVERSION
HEIGHTS RANGING FROM THE 5,500 TO 6,500 FOOT ELEVATION RANGE,
LIMITING SHOWER COVERAGE ACROSS THE STATE. A SUBTROPICAL JET
STREAM NORTHWEST OF THE ISLANDS WILL CONTINUE TO PRODUCE SOME
HIGH LEVEL ICE CRYSTAL CIRRUS CLOUDS MAINLY OVER THE WESTERN HALF
OF THE STATE. THESE HIGH LEVEL CLOUDS MAY ENHANCE SUNRISE AND
SUNSET COLORS.
IN THE BIG PICTURE, A STRONG HIGH PRESSURE RIDGE WILL REMAIN
LOCKED IN PLACE NORTH OF THE HAWAIIAN ISLANDS THROUGH MUCH OF
NEXT WEEK, RESULTING IN A FAIRLY STABLE AND BREEZY TYPICAL SUMMER
TIME TRADE WIND WEATHER PATTERN. ONE WRINKLE IN THE FORECAST IS A
WEAK UPPER LEVEL TROUGH, SHOWN ON BOTH 500MB AND 700MB MODEL
STREAMLINES, DRIFTING OVER THE ISLANDS LATER TONIGHT. THIS WEAK
TROUGH MAY LIFT SUBSIDENCE INVERSION HEIGHTS ENOUGH FOR A SUBTLE
INCREASE IN LOCAL ISLAND SHOWER ACTIVITY LATER TONIGHT THROUGH
EARLY SUNDAY MORNING. OTHERWISE THE RIDGE BUILDS BACK IN RATHER
QUICKLY WITH A RETURN TO DRY AND BREEZY SUMMER TIME WEATHER
THROUGH MUCH OF NEXT WEEK. IN THE LONG RANGE OUTLOOK, OPERATIONAL
MODELS AND MODEL BLENDS ARE SUGGESTING A SLIGHT INCREASE IN LOW
LEVEL MOISTURE AND POSSIBLY A MODEST INCREASE IN SHOWER ACTIVITY
FROM WEDNESDAY NIGHT ONWARD.
AVIATION
A STRONG HIGH PRESSURE RIDGE ANCHORED NORTH OF THE HAWAIIAN
ISLANDS WILL KEEP FAIRLY STABLE AND BREEZY EASTERLY TRADE WINDS
ACROSS THE REGION LASTING INTO MUCH OF NEXT WEEK. A FAIRLY STABLE
ENVIRONMENT WILL KEEP ONLY BRIEF PASSING SHOWERS IN THE FORECAST,
FAVORING WINDWARD AND MOUNTAIN AREAS IN THE OVERNIGHT TO EARLY
MORNING HOURS.
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
MODERATE TRADE WINDS WILL STRENGTHEN TO AREAWIDE FRESH TO LOCALLY
STRONG TODAY IN RESPONSE TO A TIGHT PRESSURE GRADIENT DOWNSTREAM
OF A LARGE HIGH NORTH OF THE ISLANDS. THIS HAS PROMPTED AN ALL
WATER SMALL CRAFT ADVISORY THAT WILL BE IN EFFECT THROUGH THE
WEEKEND. THE HIGH WILL SLIGHTLY WEAKEN AND SLIDE EAST BY THE
MIDDLE OF NEXT WEEK. THIS WILL RESULT IN TRADES DROPPING BACK TO
MORE MODERATE MAGNITUDES THROUGH THE END OF THE WEEK. WINDS IN THE
NOTORIOUSLY WINDER EASTERN ISLAND BAYS/CHANNELS AND SOUTH OF BIG
ISLAND WILL REMAIN FRESH TO STRONG THROUGH THE MAJORITY OF NEXT
WEEK.
A SLOWLY DECLINING SOUTH SWELL WILL HAVE SURF ALONG SOUTH-FACING
SHORES GRADUALLY FALLING BELOW SUMMER AVERAGES THIS WEEKEND.
BACKGROUND, LONG PERIOD SOUTHERLY SWELL WILL HOLD INTO NEXT WEEK
UNTIL THE ARRIVAL OF A NEAR 3 FOOT LONG PERIOD SWELL FILLS IN
LATE TUESDAY THROUGH WEDNESDAY. THIS SWELL MAY BOOST SOUTH-FACING
SHORE SURF HEIGHTS TO NEAR SUMMERTIME AVERAGES (~5 FT) WEDNESDAY.
EAST-FACING SHORE CHOP WILL INCREASE OVER THE WEEKEND, BECOMING
ROUGH AND CHOPPY, IN RESPONSE TO STRENGTHENED TRADE FLOW.
FIRE WEATHER
BREEZY, GUSTY, AND RATHER DRY CONDITIONS WILL CONTINUE INTO EARLY
NEXT WEEK. MINIMUM RELATIVE HUMIDITY AT LOWER LEEWARD ELEVATIONS
WILL LIKELY FALL AT OR BELOW 45 PERCENT EACH AFTERNOON.
TEMPERATURE INVERSION HEIGHTS WILL DROP AS LOW AS 5,000 FEET.
THIS WILL RESULT IN NEAR CRITICAL FIRE WEATHER CONDITIONS OVER DRY
LEEWARD AREAS AT TIMES, THOUGH NO HEADLINES (WATCHES OR
WARNINGS) WILL BE ISSUED SINCE THE KEETCH BYRAM DROUGHT INDEX
WILL REMAIN BELOW THE 600 THRESHOLD AT HONOLULU.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR ALL HAWAIIAN
WATERS.
DISCUSSION...BOHLIN
AVIATION...BOHLIN
MARINE...BLOOD
FIRE WEATHER...BOHLIN
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