777
FXHW60 PHFO 090200
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
400 PM HST THU MAY 8 2025
SYNOPSIS
A TYPICAL TRADE WIND PATTERN WILL PERSIST OVER THE NEXT SEVERAL
DAYS. THE ONLY SUBTLE FLUCTUATIONS WILL COME IN THE WAY OF MORE
TRADE-SHELTERED LOCAL LIGHT BREEZE DEVELOPMENT AND PRIMARILY
WINDWARD ENHANCED RAINFALL BASED UPON PERIODIC POCKETS OF HIGHER
MOISTURE ADVECTING IN ON THE TRADES. BETTER ORGANIZED WINDWARD
SHOWERS MAY SPILL OVER INTO LEEWARD COMMUNITIES. CLEAR MORNING
SKIES MAY ALSO LEAD TO ENHANCED AFTERNOON LEEWARD SLOPE SHOWERS,
ESPECIALLY OVER REGIONS THAT EXPERIENCE MORE EFFICIENT SEA BREEZE
BEHAVIOR.
DISCUSSION
AFTERNOON SATELLITE AND RADAR HAVE SHOWN A DECREASE IN SHOWER
ACTIVITY THROUGHOUT THE DAY. A COUPLE OF CAUSATIONS COULD BE MORE
SUBSIDENCE BROUGHT ON BY WESTERN UPPER RIDGING ADVANCING INTO THE
AREA ALONG WITH AN INFLUX OF SLIGHTLY DRIER LOWER LEVEL AIR.
TODAY'S WIDESPREAD RAINFALL HAS BEEN VERY LIGHT WITH THE
MAJORITY OF THE HIGHEST WINDWARD TOTALS COMING IN AT UNDER A
COUPLE TENTHS OF AN INCH. SIMILAR WEATHER OF CLOUDIER SKIES AND
INTERMITTENT SHOWERS WITH HIGHER RAINFALL BEING FOCUSED ALONG
WINDWARD MAUKA EXPOSURES CAN BE EXPECTED THROUGH THE MIDDLE OF THE
MONTH.
IN THE SYNOPTIC, BROAD UPPER LEVEL TOUGHING OVER THE HAWAIIAN
ISLANDS IS EXITING STAGE RIGHT AS A LARGE UPPER RIDGE BUILDS IN
FROM THE WEST NORTHWEST THE NEXT COUPLE OF DAYS. THIS WILL
MAINTAIN A MORE SHALLOW BOUNDARY LAYER AS SUBSIDENCE LOWERS THE
MID-LEVEL INVERSION. OTHER THAN A FEW SHORT LIVED HIGHER BOUTS OF
MOISTURE RIDING IN AROUND THE SOUTHEASTERN PERIPHERY OF THE
UPPER RIDGE, 850-700 MB LAYER MOISTURE WILL GENERALLY BE MORE DRY
THAN WET (OR UNDER 50% RELATIVE HUMIDITY) THROUGH SATURDAY. THE
HIGHER MOISTURE IS PROGGED TO REMAIN NORTH OF THE ISLANDS WITH
FRIDAY'S GREATEST RAIN PROBABILITIES BEING CONFINED TO KAUAI.
MAINLY CLEAR SKIES WILL LEAD TO MORE SEA BREEZE (SHOWER) ACTIVITY
ACROSS SUCH REGIONS AS LEEWARD BIG ISLAND AND SOUTH/UPCOUNTRY
MAUI THE NEXT COUPLE OF DAYS. LEEWARD PLAINS SUCH AS EWA ON OAHU
AND DOWNSLOPE WEST KAUAI WILL HEAT UP UNDER MOSTLY SUNNY
CONDITIONS. AFTERNOON MID TO UPPER 80S MAY ATTAIN MAXIMUM
TEMPERATURE RECORDS WITHIN THESE AREAS AND URBAN CENTERS (89 F IS
HONOLULU'S FRIDAY MAXIMUM TEMPERATURE RECORD).
AS THE UPPER HIGH MOVES EAST TO THE NORTH OF THE ISLANDS, MORE
MOISTURE RICH AIR IS FORECAST TO MOVE ACROSS THE ISLANDS FROM THE
EAST NORTHEAST EARLY TO MID NEXT WEEK. THE SURFACE HIGH WILL
SETTLE FAR NORTHEAST OF THE STATE AND THIS WILL GUARANTEE
CONTINUED BREEZY TRADES THROUGH THE MIDDLE OF NEXT WEEK. THE
AMOUNT OF STATEWIDE RAIN WILL PRIMARILY DEPEND UPON THE STRENGTH
AND INFLUENCE OF THE UPPER RIDGE CENTERED NORTH OF THE ISLANDS.
AMPLE MOISTURE WILL BE IN PLACE, SO DAILY RAINFALL WILL BE
DEPENDENT UPON THE EBB AND FLOW OF INVERSION HEIGHT/SUBSIDENCE (OR
LACK THEREOF). GLOBAL DETERMINISTIC NWP GUIDANCE, AS WELL AS
RESPECTIVE ENSEMBLE MEMBER PATTERNS, LEAN TOWARD A MORE WET START
TO EARLY NEXT WEEK WITH EACH SUBSEQUENT DAY HAVING SLIGHTLY HIGHER
RAIN PROBABILITIES. IN COMPARISON TO THE NEXT COUPLE OF RELATIVELY
DRIER DAYS, NEXT WEEK'S RAIN BEHAVIOR CAN BEST BE CLASSIFIED AS
MORE WET TRADES...WIDESPREAD RAIN OF LOW ACCUMULATION. LATTER
PERIOD RAINFALL (FROM TUESDAY ONWARD) WILL BECOME MORE MODERATE TO
LOCALLY HEAVY OVER WINDWARD EXPOSURES.
AVIATION
HIGH PRESSURE TO THE NORTH ALONG WITH A STABLE ATMOSPHERE WILL
ALLOW A BREEZY TRADE WIND PATTERN TO CONTINUE THROUGH THE NEXT
SEVERAL DAYS. SHOWERS WILL PRIMARILY FOCUS OVER WINDWARD AND
MOUNTAIN AREAS AS WELL AS THE NIGHT TIME HOURS. PERIODS OF
ENHANCED SHOWER ACTIVITY COULD LEAD TO TEMPORARY MVFR CONDITIONS
AT TIMES, HOWEVER VFR CONDITIONS WILL LIKELY PREVAIL.
AIRMET TANGO REMAINS IN EFFECT FOR MODERATE LOW-LEVEL TURBULENCE
OVER AND IMMEDIATELY SW THROUGH NW OF ALL ISLAND MOUNTAINS DUE TO
THE LOCALLY BREEZY TRADE WINDS. THIS AIRMET WILL LIKELY CONTINUE
FOR THE NEXT FEW DAYS. AIRMET SIERRA FOR MOUNTAIN OBSCURATION
IS NOT CURRENTLY IN EFFECT BUT COULD BE IN EFFECT TONIGHT FOR
WINDWARD AND MOUNTAIN AREAS OF ALL ISLANDS AS SHOWERS RETURN.
MARINE
A SURFACE RIDGE THAT IS CURRENTLY SITUATED NORTH OF THE ISLANDS
WILL REMAIN IN PLACE THROUGH EARLY NEXT WEEK, ALLOWING FRESH TO
LOCALLY STRONG EASTERLY TRADE WINDS TO PERSIST FOR AT LEAST THE
NEXT SEVERAL DAYS. A SMALL CRAFT ADVISORY (SCA) CURRENTLY REMAINS
IN EFFECT FOR THE TYPICAL WINDY WATERS AND CHANNELS AROUND MAUI
COUNTY AND THE BIG ISLAND. THIS SCA WILL LIKELY NEED TO BE
EXTENDED IN TIME INTO NEXT WEEK.
SURF ALONG SOUTH-FACING SHORES WILL REMAIN BELOW AVERAGE INTO
FRIDAY AS A SMALL BACKGROUND SOUTH SWELL LINGERS. A FRESH LONG-
PERIOD SOUTH-SOUTHWEST SWELL IS EXPECTED TO ARRIVE FRIDAY,
BRINGING AN UPWARD TREND WITH ABOVE-AVERAGE SURF THIS WEEKEND. THE
FORECAST REMAINS ON TRACK WITH THIS SOUTH SWELL, SO MINIMAL
CHANGES HAVE BEEN MADE. THE LATEST GUIDANCE CONTINUES TO INDICATE
THAT FORERUNNERS WILL BEGIN FILLING IN FRIDAY, WITH THE SWELL
PEAKING LATE SATURDAY THROUGH SUNDAY. THIS SWELL PEAKED ABOVE
GUIDANCE AT THE AMERICAN SAMOA PACIOOS BUOY EARLIER THIS WEEK, AND
IS EXPECTED TO BRING ADVISORY-LEVEL SURF TO SOUTH FACING SHORES.
SURF ALONG EXPOSED NORTH AND WEST-FACING SHORES WILL GRADUALLY
LOWER AND SLOWLY SHIFT OUT OF THE NORTH-NORTHEAST OVER THE NEXT
SEVERAL DAYS. SURF ALONG EAST-FACING SHORES WILL REMAIN ROUGH AND
CHOPPY THROUGHOUT THE NEXT FEW DAYS DUE TO THE TRADE WINDS, WITH
HEIGHTS HOVERING AROUND AVERAGE EACH DAY.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST SATURDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...BLOOD
AVIATION...TSAMOUS
MARINE...VAUGHAN
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