505
FXHW60 PHFO 041353
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
353 AM HST FRI JUL 4 2025
SYNOPSIS
A HIGH PRESSURE RIDGE WILL BUILD NORTH OF THE HAWAIIAN ISLANDS
LASTING INTO EARLY NEXT WEEK. EXPECT STABLE TRADE WINDS WITH BRIEF
PASSING SHOWERS AND BREEZY WINDS THROUGH AT LEAST TUESDAY. SHOWER
ACTIVITY WILL FAVOR WINDWARD SLOPES, AND ASIDE FROM AFTERNOON
SHOWERS OVER THE KONA SLOPES OF THE BIG ISLAND, LEEWARD AREAS WILL
REMAIN MOSTLY DRY.
DISCUSSION
THE SATELLITE IMAGERY THIS MORNING SHOWS FAIRLY STABLE CLOUDS
RIDING INTO THE WINDWARD SLOPES OF EACH ISLAND ON THE TRADE WINDS.
THESE CLOUDS WILL NOT PRODUCE MUCH SHOWER ACTIVITY DUE TO THE
STABLE CONDITIONS CREATED BY A HIGH PRESSURE RIDGE ALOFT, SHOWN ON
500 MB STREAMLINES. SUBSIDENCE TEMPERATURE INVERSION HEIGHTS WILL
REMAIN IN THE 5,000 TO 6,000 FOOT ELEVATION RANGE TODAY IN A
FAIRLY DRY ENVIRONMENT. BRIEF PASSING SHOWERS ARE POSSIBLE IN THIS
STABLE BOUNDARY LAYER, MAINLY OVER WINDWARD AND MOUNTAIN AREAS IN
THE OVERNIGHT TO EARLY MORNING HOURS.
A BROAD HIGH PRESSURE RIDGE WILL REMAIN LOCKED IN PLACE NORTH OF
THE STATE THROUGH MUCH OF NEXT WEEK. MODERATE TO BREEZY EASTERLY
TRADE WINDS WILL CONTINUE DURING THIS EXTENDED FORECAST TIME
PERIOD. 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 SHOWER ACTIVITY
OR INSTABILITY. THIS WILL LIMIT WINDWARD RAINFALL ACTIVITY INTO
THE ISOLATED TO SCATTERED RANGE OVER WINDWARD AND THE KONA SLOPES
OF THE BIG ISLAND WITH DRY CONDITIONS CONTINUING OVER LEEWARD
AREAS. SEE THE FIRE WEATHER SECTION BELOW FOR ADDITIONAL
DISCUSSION. A SLIGHT DECREASE IN TRADE WINDS IS EXPECTED
WEDNESDAY.
AVIATION
A HIGH PRESSURE RIDGE WILL STRENGTHEN NORTH OF THE STATE OVER THE
NEXT SEVERAL DAYS PRODUCING MODERATE TO BREEZY TRADE WINDS. A
FAIRLY STABLE ENVIRONMENT WILL KEEP ONLY BRIEF PASSING SHOWERS IN
THE FORECAST INTO THE WEEKEND.
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 TO THE NORTH WILL STRENGTHEN, CAUSING STRONG TRADE
WINDS TO DEVELOP THROUGH THE WEEKEND AND INTO THE BEGINNING OF
NEXT WEEK. THE HIGH WILL THEN WEAKEN SLIGHTLY NEXT WEEK, CAUSING
TRADE WINDS TO MARGINALLY DECREASE INTO THE BREEZY TO LOCALLY
STRONG RANGE BY THE LATER HALF OF NEXT WEEK. THE CURRENT SMALL
CRAFT ADVISORY HAS BEEN EXPANDED IN COVERAGE TO INCLUDE THE REST
OF THE CHANNELS AND IS IN EFFECT THROUGH THE WEEKEND. IT WILL
LIKELY BE EXTENDED INTO NEXT WEEK IF TRADE WINDS REMAIN STRONG.
SURF FOR SOUTH FACING SHORES WILL GRADUALLY DECLINE THROUGH THE
WEEKEND BELOW THE SUMMERTIME AVERAGE AS THE CURRENT S SWELL
DECLINES. TINY, LONG PERIOD S SWELLS WILL THEN HOLD INTO NEXT WEEK
UNTIL A NEW SMALL LONG PERIOD SWELL LOOKS TO FILL IN BY TUESDAY
NIGHT. THIS NEW SWELL COULD BOOST SURF HEIGHTS NEAR THE SUMMERTIME
AVERAGES (5 FT) BY THE MIDDLE OF NEXT WEEK.
SURF FOR EAST FACING SHORES WILL INCREASE THIS WEEKEND AND BECOME
MORE ROUGH AND CHOPPY AS TRADE WIND SPEEDS INCREASE AND THE NORTH
SHORE SURF WILL REMAIN SEASONALLY 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 KAUAI NORTHWEST
WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-OAHU LEEWARD WATERS-
KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-MAUI COUNTY LEEWARD
WATERS-MAALAEA BAY-PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND
LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS.
DISCUSSION...BOHLIN
AVIATION...BOHLIN
MARINE...TSAMOUS
FIRE WEATHER...BOHLIN
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