089
FXHW60 PHFO 051325
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
325 AM HST SUN OCT 5 2025
SYNOPSIS
LIGHT TO MODERATE WINDS WILL PREVAIL THROUGH THE REST OF TODAY. 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 THE WEEK.
DISCUSSION
LATEST OBSERVATIONS AND ADVANCED SCATTEROMETER PASS OF THE
ISLANDS INDICATE LIGHT TO LOCALLY MODERATE EASTERLY TRADES
PREVAIL ACROSS THE REGION THIS MORNING -- JUST WEAK ENOUGH TO
SUPPORT LOCALIZED SEA BREEZES LATER TODAY. MEANWHILE REFLECTIVITY
SHOWS ISOLATED SHOWERS TRICKLING INTO THE WINDWARD AND MAUKA AREA
OF MOST ISLANDS, PRODUCING LITTLE TO NO PRECIPITATION. THE ONLY
NOTABLE EXCEPTION BEING THE HILO AREA ON THE BIG ISLAND, WHERE A
HEAVIER SHOWER DEVELOPED BRIEFLY. THIS MORNING'S 12Z SOUNDING FROM
HILO SHOWS THE TEMPERATURE INVERSION HEIGHTS RANGING FROM 6000 TO
7000 FEET, WITH PRECIPITABLE WATER VALUES SLIGHTLY LOWER THAN
YESTERDAY, AT AROUND 1.24 INCHES.
LIGHT TO LOCALLY MODERATE TRADES WILL CONTINUE THROUGH TODAY.
LATEST MODEL GUIDANCE OF THE GFS AND ECMWF CONTINUE TO DEPICT A
BROAD SURFACE TROUGH DEVELOPING JUST NORTHEAST OF THE ISLANDS ON
MONDAY, WITH A WELL-DEFINED LOW ALOFT. MODELS PROJECT THIS TROUGH
TO SLOWLY MEANDER WESTWARD TOWARD THE ISLANDS AND PASSING OVER
BETWEEN MONDAY AND MID-WEEK, THEN BECOMING LESS DEFINED AS IT AND
THE ASSOCIATED LOW ALOFT EXITS WELL NORTH OF THE STATE. WINDS
ACROSS THE ISLANDS DURING THIS TIME WILL BECOME NOTICEABLY
WEAKER, VEERING EAST-SOUTHEASTERLY, AND TRANSITIONING TO A MORE
PRONOUNCED LAND AND SEA BREEZE PATTERN ACROSS THE ENTIRETY OF THE
HAWAIIAN ISLANDS. IN SUCH A PATTERN WHERE THE LOCAL SCALE WINDS
ARE VIRTUALLY ABSENT, ISLAND HEATING WILL SUPPORT SEA BREEZES
DURING THE DAY, WHICH WILL ENHANCE LEEWARD AND INTERIOR SHOWER
ACTIVITY, AND OVERNIGHT COOLING WILL DRIVE LAND BREEZES AT NIGHT,
CLEARING THE NIGHT SKIES AND LIMITING SHOWERS.
THE LAND/SEA BREEZE REGIME IS PROGGED TO CONTINUE THROUGH THE
LATTER HALF OF THE WEEK UNTIL THE AFOREMENTIONED SURFACE TROUGH
AND ASSOCIATED LOW ALOFT EXIT THE VICINITY OF THE ISLANDS LATE
FRIDAY. THEREAFTER, MODERATE TRADES ARE EXPECTED TO RETURN TO THE
ISLANDS JUST IN TIME FOR THE WEEKEND, PERSISTING THROUGH THE
REMAINDER OF THE OUTLOOK PERIOD.
AVIATION
LIGHT TO LOCALLY MODERATE TRADES CONTINUE TO PREVAIL ACROSS THE
HAWAIIAN ISLANDS, BRINGING PERIODS OF MVFR CONDITIONS IN ISOLATED
SHOWERS ACROSS WINDWARD AND MAUKA LOCATIONS. WINDS WILL BEGIN TO
DIMINISH INTO A MORE LAND AND SEA BREEZE PATTERN TOWARD THE LATTER
END OF THE TAF OUTLOOK, INCREASING CLOUDS AND SHOWER ACTIVITY
ACROSS LEEWARD AND INTERIORS OF THE ISLANDS. LOCALIZED MVFR IS
POSSIBLE WITHIN ANY SHOWER ACTIVITY, HOWEVER, MOST SITES WILL
REMAIN VFR.
NO AIRMETS ARE CURRENTLY IN EFFECT.
MARINE
HIGH PRESSURE THE NORTHEAST WILL CONTINUE TO BRING MODERATE EAST-
NORTHEAST TRADES TO THE REGION TODAY. A DISSIPATING FRONT AND
TROUGH TO THE NORTHWEST WILL CONTINUE TO WEAKEN TODAY. A NEW
TROUGH IS EXPECTED TO DEVELOP NORTHEAST OF THE STATE OVER THE NEXT
COUPLE OF DAYS, AND THEN MOVE TO THE SOUTHEAST, AND WILL WEAKEN
WINDS TO LIGHT AND VARIABLE THROUGH THE FIRST HALF OF NEXT WEEK.
THE CURRENT MODERATE, MEDIUM-PERIOD NORTH-NORTHWEST (330 DEGREE)
SWELL CONTINUES TO FILL IN, AND IS EXPECTED TO PEAK TODAY BELOW
HIGH SURF ADVISORY (HSA) LEVELS. THE SWELL WILL THEN SLOWLY FADE
OVER THE NEXT FEW DAYS. 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 TODAY, 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 OVER
THE NEXT SEVERAL DAYS, EVEN WITH THE SLIGHT BOOST TODAY WITH THE
BRIEF UPTICK IN TRADES.
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 7000 FEET
THROUGH TONIGHT.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...PIERCE
AVIATION...PIERCE
MARINE...M BALLARD
FIRE WEATHER...PIERCE
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