882
FXHW60 PHFO 151338
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
338 AM HST TUE JUL 15 2025
SYNOPSIS
A HIGH PRESSURE SYSTEM WILL REMAIN IN PLACE NORTH OF THE HAWAIIAN
ISLANDS THROUGH THE WEEKEND KEEPING MODERATE TO LOCALLY BREEZY
TRADE WINDS INTO THE EXTENDED RANGE FORECAST. A DISTURBANCE
PASSING THROUGH THE ISLANDS TODAY WILL BRIEFLY INCREASE SHOWER
ACTIVITY THROUGH THE MORNING HOURS. MORE STABLE CONDITIONS WITH
LIMITED SHOWER ACTIVITY RETURNS INTO FRIDAY. ANOTHER UPPER LEVEL
DISTURBANCE MOVES OVER THE ISLANDS PRODUCING A SLIGHT INCREASE IN
SHOWER ACTIVITY FORECAST FROM FRIDAY AFTERNOON THROUGH THE
WEEKEND.
DISCUSSION
AN EASTERLY WAVE MOVING THROUGH THE ISLANDS SHOWS UP ON THIS
MORNINGS SATELLITE IMAGERY AS UNSTABLE CLOUD BANDS MOVING THROUGH
THE CENTRAL AND WESTERN ISLANDS. MORE STABLE STRATOCUMULUS CLOUDS
ARE FILLING IN BEHIND THIS TROUGH AS THE RIDGE BUILDS OVER THE
STATE AND WE RETURN TO MORE STABLE WEATHER CONDITIONS LATER TODAY.
LOCAL RADAR IMAGERY SHOWS SCATTERED TO NUMEROUS SHOWER BANDS
DRIFTING INTO THE WINDWARD AND MOUNTAIN SLOPES OF EACH ISLAND ON
THE TRADE WINDS. A FEW OF THE STRONGEST SHOWERS MAY BRING BRIEF
SHOWERS TO THE TYPICALLY DRIER LEEWARD AREAS.
AFTER A WET SUMMER MORNING, EXPECT DRIER AND MORE STABLE
CONDITIONS TO DEVELOP ACROSS THE STATE LASTING INTO FRIDAY, AS
HIGH PRESSURE WILL KEEP A SUBSIDENCE CAP ON VERTICAL CLOUD
DEVELOPMENT. SUBTLE CHANGES IN THE ISLAND CLOUD AND SHOWER
PATTERN WILL BECOME LESS STABLE FROM LATE FRIDAY ON INTO THE
WEEKEND, AS A WEAK UPPER LEVEL LOW INJECTS SOME INSTABILITY ACROSS
THE HAWAII REGION. A SLIGHT INCREASE IN SHOWER TRENDS ARE
ANTICIPATED MAINLY DURING THE OVERNIGHT TO EARLY MORNING HOURS
FAVORING THE WINDWARD AND MOUNTAIN AREAS.
CONFIDENCE IN THESE SHOWER TRENDS REMAIN MODERATE AT THIS TIME,
AS THE STRENGTH OF THE UPPER LOW IS CURRENTLY PROJECTED TO BE ON
THE WEAKER SIDE OF THE EQUATION. MORE DETAILS WILL BECOME CLEARER
LATER THIS WEEK, AS THE TIME PERIOD GROWS CLOSER, AND OUR
CONFIDENCE ON ISLAND BY ISLAND SHOWER TRENDS IMPROVE.
AVIATION
A HIGH PRESSURE RIDGE REMAINS IN PLACE NORTH OF THE HAWAIIAN
ISLANDS THIS WEEK. MODERATE TO LOCALLY BREEZY EASTERLY TRADE WINDS
REMAIN IN THE FORECAST. SHOWER TRENDS WILL REMAIN ELEVATED THIS
MORNING AS A LOW LEVEL TROUGH PASSES WESTWARD THROUGH THE ISLAND
CHAIN. PERIODS OF MVFR CONDITIONS ARE EXPECTED IN ANY SHOWERS,
ESPECIALLY AFFECTING WINDWARD AIRFIELDS. WEATHER CONDITIONS WILL
TREND TO THE STABLE SIDE THROUGH THE DAY WITH LIMITED CLOUDS AND
SHOWERS THROUGH THE WEEK.
AIRMET SIERRA FOR MOUNTAIN OBSCURATION REMAINS IN EFFECT FOR NORTH
AND EAST SLOPES OF MOST ISLANDS.
MARINE
A RIDGE OF HIGH PRESSURE WILL REMAIN FAR NORTH OF THE STATE
THROUGHOUT THE WEEK. TRADES SHOULD GRADUALLY STRENGTHEN TODAY. A
SMALL CRAFT ADVISORY (SCA) IS IN EFFECT FOR THE TYPICAL WINDY
AREAS AROUND MAUI COUNTY AND THE BIG ISLAND STARTING 6AM THIS
MORNING. FRESH TO LOCALLY STRONG TRADES WILL LIKELY PERSIST
THROUGH MOST OF THE WEEK, ALTHOUGH WE COULD SEE WINDS DROP BELOW
SCA CRITERIA AS A WEAK TROUGH DEVELOPS OVER THE WESTERN END OF THE
STATE INTO THE WEEKEND.
SURF ALONG SOUTH FACING SHORES SHOULD SEE A SMALL BOOST OVER THE
NEXT FEW DAYS DUE TO A PAIR OF SOUTH AND SOUTH-SOUTHEAST SWELLS. A
LONG-PERIOD SOUTH SWELL SHOULD PEAK TODAY NEAR SUMMER AVERAGES.
AS THIS SWELL DECLINES A REINFORCING SWELL FROM THE SOUTH-
SOUTHEAST SHOULD FILL IN LATER TODAY INTO WEDNESDAY. THIS SHOULD
MAINTAIN SURF HEIGHTS THROUGH THE MIDDLE OF THE WEEK. SURF SHOULD
GRADUALLY DECLINE THURSDAY INTO FRIDAY, BUT ANOTHER SMALL INCREASE
IS EXPECTED INTO THE WEEKEND AS A NEW LONG-PERIOD SOUTHWEST SWELL
ARRIVES FROM THE TASMAN SEA.
SURF ALONG EAST FACING SHORES WILL CONTINUE TO REMAIN ROUGH AND CHOPPY
WITH SURF HEIGHTS GETTING A SLIGHT INCREASE AS THE TRADES
STRENGTHEN. SURF ALONG NORTH FACING SHORES WILL CONTINUE TO
DECLINE THROUGH WEDNESDAY.
FIRE WEATHER
TRADE WINDS WILL REMAIN IN THE MODERATE TO LOCALLY BREEZY RANGE
INTO THE UPCOMING WEEKEND. AFTER A PERIOD OF HIGHER HUMIDITY
LEVELS AND ELEVATED SHOWER TRENDS THIS MORNING, WEATHER CONDITIONS
WILL DRY OUT AND BECOME MORE STABLE INTO FRIDAY. ANOTHER INCREASE
IN SHOWER TRENDS MAY DEVELOP FROM FRIDAY AFTERNOON THROUGH THE
WEEKEND AS AN UPPER LEVEL DISTURBANCE MOVES OVER THE ISLAND CHAIN.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...BOHLIN
AVIATION...BOHLIN
MARINE...WALSH
FIRE WEATHER...BOHLIN
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