905
FXHW60 PHFO 050138
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
338 PM HST SAT OCT 4 2025
SYNOPSIS
LIGHT TO MODERATE WINDS WILL PREVAIL THROUGH THE REST OF THE
WEEKEND. A BROAD SURFACE TROUGH WILL DEVELOP NORTHEAST OF THE
STATE EARLY NEXT WEEK, THEN PROPAGATE ACROSS THE ISLAND CHAIN. AS
THIS OCCURS, WINDS WILL WEAKEN AND BECOME EAST-SOUTHEASTERLY,
RESULTING IN A DAYTIME SEA BREEZE AND NIGHTTIME LAND BREEZE
REGIME. MODERATE TRADE WINDS WILL RETURN NEAR THE END OF NEXT
WEEK.
DISCUSSION
SURFACE OBSERVATIONS ACROSS THE ISLANDS AND AN ADVANCED
SCATTEROMETER PASS FROM EARLIER TODAY SHOW MODERATE EASTERLY TRADE
WINDS PREVAILING ACROSS THE REGION. THESE PREVAILING WINDS ARE
JUST LIGHT ENOUGH TO SUPPORT LOCALIZED SEA BREEZES THIS AFTERNOON,
WHICH HAVE RESULTED IN CLOUD BUILDUPS AND A FEW ISOLATED SHOWERS
ACROSS SOME LEEWARD AND INTERIOR SECTIONS OF THE ISLANDS. RAINFALL
ACCUMULATIONS HAVE BEEN LIGHT ACROSS MOST OF THE STATE TODAY,
HOWEVER, WITH THE NOTABLE EXCEPTION BEING A HEAVIER SHOWER THAT
DEVELOPED OVER THE KAILUA-KONA AIRPORT DURING THE MORNING HOURS
BEFORE IT QUICKLY DISSIPATED. AFTERNOON SOUNDINGS FROM LIHUE AND
HILO SHOW THE TEMPERATURE INVERSION HEIGHTS RANGING FROM 6000 TO
7500 FEET TODAY, WITH PRECIPITABLE WATER VALUES VIRTUALLY
UNCHANGED FROM LAST NIGHT, AROUND 1.3 TO 1.4 INCHES.
LIGHT TO LOCALLY MODERATE WINDS WILL CONTINUE THROUGH THE REST OF
THE WEEKEND. AS PREVIOUS DISCUSSIONS HAVE MENTIONED, LATEST
GLOBAL MODELS SHOW A SURFACE TROUGH DEVELOPING JUST NORTHEAST OF
THE ISLANDS ON MONDAY, WITH A WELL-DEFINED LOW ALOFT. THIS TROUGH
WILL MOVE NEAR AND THEN OVER THE WESTERN ISLANDS FROM MONDAY
MORNING THROUGH MID-WEEK, THEN WILL BECOME LESS DEFINED AS IT
WEAKENS BY MID-WEEK. THROUGHOUT THIS TIME, BACKGROUND WIND FLOW
WILL BECOME WEAK AND VEER EAST-SOUTHEASTERLY. AS A RESULT, ISLAND
HEATING WILL SUPPORT SEA BREEZES EACH DAY, AND OVERNIGHT COOLING
WILL DRIVE LAND BREEZES EACH NIGHT. IN THIS PATTERN, DAYTIME SEA
BREEZES WILL ENHANCE LEEWARD AND INTERIOR SHOWER ACTIVITY, WHILE
LAND BREEZES OVERNIGHT WILL CLEAR THE NIGHT SKIES, LIMITING
SHOWERS.
THIS SEA BREEZE/LAND BREEZE REGIME IS FORECAST TO CONTINUE
THROUGH LATTER HALF OF THE WEEK UNTIL THE AFOREMENTIONED SURFACE
TROUGH EXITS THE VICINITY OF THE ISLANDS LATE FRIDAY. MODERATE
TRADE WINDS LOOK TO RETURN TO THE ISLANDS NEXT WEEKEND.
AVIATION
MODERATE EAST-NORTHEAST TRADE WINDS ARE EXPECTED
THROUGH SUNDAY NIGHT, BRINGING ISOLATED TO SCATTERED SHOWERS
MAINLY OVER WINDWARD AREAS. TRADE WIND FLOW MAY BE JUST WEAK
ENOUGH TO ALLOW FOR AFTERNOON SEA BREEZES THE REST OF THIS
AFTERNOON ACROSS LEEWARD AREAS, RESULTING IN CLOUDS AND ISOLATED
SHOWERS. LOCALIZED MVFR IS POSSIBLE WITHIN PASSING SHOWERS, BUT
MOST SITES WILL REMAIN VFR.
NO AIRMETS ARE CURRENTLY IN EFFECT.
MARINE
MODERATE EAST-NORTHEAST TRADES HAVE FILLED IN ACROSS THE STATE
TODAY AND WILL LINGER THROUGH THRU THE REMAINDER OF THE WEEKEND AS
HIGH PRESSURE BECOMES REESTABLISHED NORTH OF THE AREA. A TROUGH
MAY DEVELOP NORTHEAST OF THE STATE EARLY NEXT WEEK AND MOVE
SOUTHEAST, WEAKENING WINDS TO LIGHT AND VARIABLE THROUGH THE FIRST
HALF OF NEXT WEEK.
A MODERATE, MEDIUM-PERIOD NORTH NORTHWEST (330 DEG) SWELL WILL
FILL IN THROUGH THE NIGHT AND PEAK SUNDAY JUST BELOW HIGH SURF
ADVISORY (HSA) CRITERIA FOR NORTH FACING SHORES, BEFORE SLOWLY
FADING INTO EARLY NEXT WEEK. A SMALL MEDIUM TO LONG-PERIOD SWELL
FROM THE NORTHWEST (320 DEG) IS EXPECTED TO FILL IN MONDAY, PEAK
TUESDAY AND DECLINE THROUGH THE MIDDLE OF NEXT WEEK.
THE CURRENT SMALL, LONG-PERIOD SOUTHWEST (210 DEG) SWELL WILL
CONTINUE TO SLOWLY DECLINE INTO EARLY NEXT WEEK. A SMALL, LONG-
PERIOD SOUTHWEST SWELL MAY ARRIVE LATE SUNDAY AND BUILD INTO EARLY
NEXT WEEK BEFORE SUBSIDING. ANOTHER SMALL LONG-PERIOD SOUTHWEST
(200 DEG) SWELL IS POSSIBLE BY THE LATER HALF OF NEXT WEEK. SURF
ALONG EAST-FACING SHORES WILL REMAIN BELOW AVERAGE INTO EARLY NEXT
WEEK WITH THE A SLIGHT BOOST SATURDAY INTO SUNDAY AS MODERATE TO
FRESH TRADES BRIEFLY RETURN.
FIRE WEATHER
WIND SPEEDS AND HUMIDITY WILL REMAIN BELOW CRITICAL FIRE WEATHER
THRESHOLDS FOR THE NEXT SEVERAL DAYS. TEMPERATURE INVERSION
HEIGHTS ACROSS THE STATE WILL RANGE FROM 6000 TO 7500 FEET THROUGH
TONIGHT.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...VAUGHAN
AVIATION...TS/PARKER
MARINE...TS
FIRE WEATHER...VAUGHAN
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