949
FXHW60 PHFO 041310
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
310 AM HST SAT OCT 4 2025
SYNOPSIS
LIGHT TO LOCALLY MODERATE WINDS PREVAIL THROUGH MUCH OF THE
WEEKEND. A BROAD SURFACE LOW DEVELOPS NORTHEAST OF THE STATE EARLY
NEXT WEEK AND WILL PROPAGATE WESTWARD ACROSS THE ISLAND CHAIN,
RESULTING IN WINDS TAPERING OFF INTO A LAND AND SEA BREEZE REGIME,
PERSISTING THROUGH THE LATTER HALF OF THE WEEK. AS THE
AFOREMENTIONED LOW EXITS THE VICINITY, TRADES ARE EXPECTED TO
RETURN THROUGH THE REMAINDER OF THE OUTLOOK PERIOD.
DISCUSSION
A SLOW-MOVING FRONTAL PASSAGE NORTHWEST OF THE HAWAIIAN ISLANDS
WILL CONTINUE TO TREK SOUTHEASTWARD BEFORE STALLING AND FIZZLING
OUT BY MIDDAY TODAY. LATEST SATELLITE IMAGERY DEPICTS SCATTERED
PLUME SHOWERS SPORADICALLY AROUND THE ISLANDS, PREDOMINATELY
IMPACTING THE SMALLER ISLANDS, AS WELL AS CLOUD COVERAGE BUILD UP
WITHIN THE INTERIOR OF SOME ISLANDS. THESE SHOWERS ARE EXPECTED TO
TAPER OFF LATER THIS MORNING. LATEST 12Z SOUNDINGS DEPICTS THE
TEMPERATURE INVERSION HEIGHTS ACROSS THE STATE RANGE FROM 6500 TO
7500 FEET TODAY, WITH PRECIPITABLE WATER VALUES NEAR 1.31 INCHES
NEAR HILO.
LIGHT TO LOCALLY MODERATE WINDS PREVAIL FOR MUCH OF THE AREA
THROUGHOUT THE DAY AND CARRY THROUGH MUCH OF THE WEEKEND. LATEST
MODEL GUIDANCE OF THE GFS AND ECMWF CONTINUE TO DEPICT A BROAD
SURFACE TROUGH DEVELOPING JUST NORTHEAST OF THE STATE AROUND
MONDAY, SLOWLY PROPAGATING WESTWARD ACROSS THE ISLAND CHAIN. AS A
RESULT, WINDS WILL TAPER OFF INTO A MORE LIGHT AND VARIABLE
PATTERN. IN THE ABSENCE OF LOCAL SCALE WINDS, ISLAND HEATING WILL
DEVELOP SEA BREEZES EACH DAY, AND OVERNIGHT COOLING WILL DRIVE
DOWNSLOPING LAND BREEZES EACH NIGHT. DURING THE DAY, SEA BREEZES
WILL ENHANCE LEEWARD AND INTERIOR REGION SHOWER ACTIVITY, WHILE
LAND BREEZES OVERNIGHT WILL CLEAR THE NIGHT SKIES, LIMITING
SHOWERS.
THIS LAND AND SEA REGIME IS PROGGED TO CONTINUE THROUGH LATTER
HALF OF THE WEEK UNTIL THE AFOREMENTIONED SURFACE LOW EXITS THE
VICINITY OF THE ISLANDS LATE FRIDAY, ALLOWING TRADES TO RETURN
THROUGH THE REMAINDER OF THE OUTLOOK PERIOD.
AVIATION
MODERATE EASTERLY TRADE WINDS ARE EXPECTED THROUGH THE WEEKEND WITH
CLOUDS AND SHOWERS FOCUSED MAINLY OVER WINDWARD AND MAUKA
AREAS. TRADE WIND FLOW MAY ALLOW FOR SEA BREEZES TO DEVELOP
ACROSS LEEWARD AREAS EACH AFTERNOON, BRINGING CLOUDS AND ISOLATED
SHOWERS TO THOSE AREAS. LOCALIZED MVFR POSSIBLE WITHIN PASSING
SHOWERS, BUT MOST SITES WILL REMAIN VFR.
NO AIRMETS ARE CURRENTLY IN EFFECT.
MARINE
A COLD FRONT TO THE NORTHWEST AND A TROUGH TO THE NORTHEAST ARE
THE DRIVING FORCES TO MAINTAINING A LIGHT TO MODERATE EAST-
SOUTHEAST FLOW OVER THE AREA. WITH BOTH OF THESE FEATURES EXPECTED
TO WEAKEN TODAY, EXPECT MODERATE EAST-NORTHEAST TRADES TO FILTER
BACK IN OVER THE AREA, AND LINGER THROUGH THRU THE REMAINDER OF
THE WEEKEND. A TROUGH MAY DEVELOP NORTHEAST OF THE STATE EARLY
NEXT WEEK, ONCE AGAIN WEAKENING WINDS TO LIGHT AND VARIABLE.
A MODERATE, MEDIUM PERIOD NORTH NORTHWEST (330 DEG) SWELL GENERATED
FROM THE CURRENT LOW LOCATED FAR NORTH-NORTHWEST OF THE ISLANDS
IS EXPECTED TO FILL IN TODAY, PEAK SUNDAY JUST BELOW HIGH SURF
ADVISORY (HSA) CRITERIA FOR NORTH FACING SHORES, AND SLOWLY FADE
INTO EARLY NEXT WEEK. ANOTHER 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 6500 TO 7500 FEET TODAY.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...PIERCE
AVIATION...SHIGESATO
MARINE...M BALLARD
FIRE WEATHER...PIERCE
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