102
FXHW60 PHFO 010149
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
349 PM HST SAT NOV 30 2024
SYNOPSIS
MODERATE TRADE WINDS WILL WEAKEN TONIGHT THROUGH THE FIRST HALF
OF NEXT WEEK. CONDITIONS SHOULD REMAIN FAIRLY STABLE AND DRY,
WITH LOW CLOUDS AND MAINLY ISOLATED LIGHT SHOWERS FAVORING INTERIOR
AND MOUNTAIN LOCATIONS. RAIN CHANCES INCREASE MID TO LATE NEXT
WEEK AS A FRONT MOVES SLOWLY ACROSS THE ISLANDS.
DISCUSSION
A NARROW BAND OF HIGH CIRRUS CLOUDS IS THINNING OUT AS IT STREAMS
OVER THE CENTRAL PORTION OF THE ISLAND CHAIN FROM WEST TO EAST
THIS AFTERNOON. SOME SCATTERED LOW-LEVEL CLOUD DEVELOPMENT IS
NOTICEABLE ON VISIBLE SATELLITE IMAGERY, MAINLY OVER THE ISLAND
INTERIORS THIS AFTERNOON, THOUGH LITTLE IN THE WAY OF RETURNS
APPEAR ON RADAR. THIS INDICATES THE MODERATE TRADES ARE ALREADY
BEGINNING TO DIMINISH, ALLOWING SEA BREEZES TO FORM IN THE MORE
WIND-SHELTERED LEEWARD AREAS TODAY. THE UPPER AIR BALLOON SOUNDING
FROM HILO INDICATES A LOWERING SUBSIDENCE INVERSION OVER THE
EASTERN END OF THE STATE, WHILE LIHUE'S SHOWS THE INVERSION THERE
ERODING SOMEWHAT AS A WEAK FRONT APPROACHES THE OFFSHORE WATERS TO
THE NORTHWEST. GENERALLY STABLE CONDITIONS ALOFT WILL TEND TO
LIMIT CLOUD HEIGHTS AND KEEP THE SHOWER ACTIVITY MINIMAL, WITH
VERY LITTLE IN THE WAY OF RAINFALL FOR MOST AREAS THROUGH TONIGHT.
THE WEAK BOUNDARY APPROACHING FROM THE NORTHWEST WILL STALL AND
DISSIPATE NORTHWEST OF THE COASTAL WATERS THROUGH THE REMAINDER OF
THE WEEKEND. OTHERWISE, A WEAK SUBTROPICAL RIDGE AXIS WILL REMAIN
OVER OR NEAR THE ISLANDS WITH WEAK RIDGING ALOFT THROUGH THE MIDDLE
OF NEXT WEEK. WINDS WILL BECOME LIGHT AND VARIABLE OVER MUCH OF THE
STATE SUNDAY INTO MONDAY, THEN REMAIN ON THE LIGHTER SIDE THROUGH
WEDNESDAY. DURING THIS TIME, EXPECT CLOUDS AND SHOWERS TO FOCUS
OVER THE MOUNTAIN AND INTERIOR AREAS OF EACH ISLAND DUE TO SEA
BREEZE DEVELOPMENT DURING THE LATE MORNING/EARLY AFTERNOON EACH
DAY. RAINFALL AMOUNTS WILL BE LIGHT DUE TO THE LARGE SCALE
ATMOSPHERIC STABILITY.
BY THURSDAY, LONG-RANGE MODEL GUIDANCE CONTINUES TO SHOW A SHALLOW
COLD FRONT CREEPING INTO THE WESTERN ISLANDS FROM THE NORTHWEST.
WHILE THE GFS AND ECMWF STILL DIFFER ON THE SPEED OF THE FRONT,
INCREASED SHOWERS AND BREEZY TRADE WINDS WILL DEVELOP ALONG THE
WEAKENING BOUNDARY AS IT PROGRESSES EASTWARD. ALL ISLANDS WILL
LIKELY BENEFIT FROM A PERIOD OF ENHANCED SHOWERS ALONG THE FRONTAL
BAND, ESPECIALLY ALONG THE WINDWARD MOUNTAIN SLOPES. BOTH MODELS
HAVE THE FRONT STALLING OUT NEAR MAUI BY FRIDAY MORNING AND BREAKING
UP/DISSIPATING BY THE AFTERNOON, WITH REMNANT UNSTABLE CLOUD BANDS
DRIFTING INTO EACH ISLAND ON THE STRENGTHENING EASTERLY TRADE WINDS.
THE GLOBAL MODELS BOTH INDICATE ANOTHER FRONT APPROACHING THE STATE
FROM THE NORTHWEST SATURDAY NIGHT INTO SUNDAY, UNCERTAINTY REMAINS
WHETHER THE BOUNDARY MAKES IT TO THE ISLANDS BEFORE DISSIPATING.
AVIATION
LIGHT TO LOCALLY MODERATE TRADES WILL CONTINUE TO WEAKEN THROUGH
THE REST OF THE WEEKEND, ALLOWING FOR LOCALIZED LAND/SEA BREEZE
DEVELOPMENT TODAY THAT WILL BECOME MORE WIDESPREAD TOMORROW.
ISOLATED SHOWERS WILL FAVOR MOUNTAIN AND INTERIOR AREAS OF EACH
ISLAND DUE TO SEA BREEZE DEVELOPMENT EACH AFTERNOON, THEN CLEAR
OUT OVERNIGHT WITH THE LAND BREEZES. BRIEF MVFR CONDITIONS WILL BE
POSSIBLE IN SHOWERS, OTHERWISE, VFR CONDITIONS WILL PREVAIL.
AIRMET TANGO IS IN EFFECT FOR MODERATE TURBULENCE BETWEEN FL250
AND FL450 ACROSS THE STATE. SIGMET PAPA FOR SEVERE UPPER LEVEL
TURBULENCE IS ALSO IN EFFECT ACROSS THE EASTERN HALF OF THE
STATE. UPPER LEVEL TURBULENCE WILL LIKELY TAPER OFF FROM WEST TO
EAST THROUGH THE NIGHT INTO TOMORROW MORNING AS THE SUBTROPICAL
JET PUSHES EAST OF THE AREA.
MARINE
A COLD FRONT IS CURRENTLY STALLED NORTH OF THE COASTAL WATERS,
RESULTING IN LIGHT BACKGROUND WINDS ACROSS THE AREA. THIS LIGHT
BACKGROUND FLOW WILL SHIFT TO BLOW OUT OF SOUTHEAST ON SUNDAY.
ANOTHER FRONT WILL APPROACH FROM THE NORTHWEST EARLY NEXT WEEK
WILL KEEP GENTLE SOUTH TO SOUTHEAST WINDS IN PLACE.
THE EXTRA-LARGE NORTHWEST (310-320) SWELL THAT PEAKED WELL ABOVE
GUIDANCE LAST NIGHT CONTINUES TO SLOWLY DECLINE THIS AFTERNOON.
HOWEVER, BUOY OBSERVATIONS FROM HANALEI AND WAIMEA HAVE BEEN
ESTIMATING THE SWELL AT ABOUT 10 FEET, 15 SECONDS THIS AFTERNOON.
BASED ON BUOY DATA AND OBSERVATIONS, ALTHOUGH IT HAS DECLINED
THROUGHOUT THE DAY, THE SWELL APPEARS TO STILL BE PRODUCING
BORDERLINE WARNING-LEVEL SURF ALONG NORTH AND WEST FACING SHORES.
THEREFORE, THE HIGH SURF WARNING THAT WAS PREVIOUSLY IN EFFECT
THROUGH THIS AFTERNOON HAS NOW BEEN EXTENDED THROUGH MIDNIGHT
TONIGHT. THE EXCEPTION IS FOR WEST FACING SHORES OF THE BIG
ISLAND, WHICH HAS BEEN DOWNGRADED TO A HIGH SURF ADVISORY (HSA)
WITH THIS AFTERNOON'S FORECAST UPDATES. AS THE SWELL CONTINUES TO
DECLINE INTO THIS EVENING AND TONIGHT, SURF SHOULD DROP TO
ADVISORY LEVELS BY EARLY SUNDAY, AND FINALLY TO SUB-ADVISORY
LEVELS BY THE END OF THE WEEKEND. ADDITIONALLY, A SMALL CRAFT
ADVISORY (SCA) REMAINS IN EFFECT FOR WINDWARD WATERS AND ALL
WATERS SURROUNDING KAUAI COUNTY FOR SEAS GREATER THAN 10 FT. SEAS
ARE EXPECTED TO DROP BELOW 10 FEET BY EARLY SUNDAY, AT WHICH POINT
THE SCA WILL BE CANCELLED.
LOOKING AHEAD TO NEXT WEEK, A STRETCH OF ELEVATED NORTH AND WEST
SHORE SURF IS EXPECTED, PRODUCED BY OVERLAPPING NORTHWEST PULSES
RANGING FROM LARGE TO POTENTIALLY EXTRA-LARGE, WITH THE FIRST
ARRIVING TUESDAY AND A LARGER ONE PEAKING WEDNESDAY INTO THURSDAY.
SURF ALONG EAST FACING SHORES WILL REMAIN SLIGHTLY ELEVATED
THROUGH THE REST OF THE WEEKEND DUE TO THE LINGERING SHORT-PERIOD
NORTH-NORTHEAST SWELL. EARLY NEXT WEEK, SURF ALONG EAST FACING
SHORES WILL REMAIN SMALL. SURF ALONG SOUTH FACING SHORES WILL SEE
AN UPTICK HEADING INTO NEXT WEEK FROM A SERIES OF CONSECUTIVE
SOUTHWEST PULSES. THIS WILL RESULT IN SMALL TO MODERATE SURF,
PEAKING MONDAY AND TUESDAY.
FIRE WEATHER
CRITICAL FIRE WEATHER CONDITIONS ARE NOT EXPECTED THROUGH NEXT
WEEK, AS WINDS WILL REMAIN WELL BELOW THE RED FLAG WARNING
THRESHOLD THROUGH THURSDAY. DAYTIME RELATIVE HUMIDITY MAY BRIEFLY
TOUCH CRITICAL LEVELS OVER THE DRIER LEEWARD AREAS INTO EARLY
NEXT WEEK, BEFORE INCREASING AGAIN WITH THE ARRIVAL OF A FRONT AND
ITS ASSOCIATED SHOWERS MOVING THROUGH THE STATE DURING THE SECOND
HALF OF THE WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
HIGH SURF WARNING UNTIL MIDNIGHT HST TONIGHT FOR NIIHAU-KAUAI
LEEWARD-WAIANAE COAST-OAHU NORTH SHORE-MAUI WINDWARD WEST-KAUAI
NORTH-KOOLAU WINDWARD-MOLOKAI WINDWARD-MOLOKAI NORTH-MOLOKAI
WEST-WINDWARD HALEAKALA.
HIGH SURF ADVISORY UNTIL 6 AM HST SUNDAY FOR KONA-KOHALA.
SMALL CRAFT ADVISORY UNTIL 6 AM HST SUNDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-KAIWI CHANNEL-MAUI COUNTY WINDWARD WATERS-
BIG ISLAND WINDWARD WATERS.
DISCUSSION...TS
AVIATION...FARRIS
MARINE...VAUGHAN
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