922
FXHW60 PHFO 171347
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
347 AM HST WED DEC 17 2025
SYNOPSIS
A COLD FRONT STALLING OUT NEAR KAUAI AND OAHU TODAY WILL PRODUCE
PERIODS OF MODERATE TO LOCALLY HEAVY SHOWERS AND ISOLATED
THUNDERSTORMS ACROSS THE WESTERN HALF OF THE STATE IN AN UNSTABLE
SOUTHERLY WIND PATTERN. MORE STABLE CONDITIONS ARE FORECAST OVER
THE EASTERN ISLANDS AS A WEAK RIDGE AND SOUTHEASTERLY WINDS LIMIT
SHOWER ACTIVITY. ON THURSDAY THE FRONT WEAKENS INTO A TROUGH AND
LIFTS NORTHWESTWARD BACK OVER KAUAI AND NIIHAU, PROVIDING ANOTHER
ROUND OF SHOWERS OVER THE GARDEN ISLE WITH IMPROVING WEATHER
TRENDS FOR MOLOKAI AND OAHU. THE HIGH PRESSURE RIDGE ALOFT WILL
SLOWLY BUILD BACK IN OVER THE ISLANDS AS THE TROUGH NORTH OF THE
STATE FILLS IN AND LIFTS NORTHWARD, HERALDING A RETURN STATEWIDE
TO MORE STABLE EASTERLY TRADE WIND WEATHER JUST IN TIME FOR THE
WEEKEND. THESE MORE TYPICAL AND STABLE MODERATE TO BREEZY TRADE
WINDS WITH BRIEF WINDWARD AND MOUNTAIN SHOWERS WILL LAST THROUGH
CHRISTMAS DAY.
DISCUSSION
THE SHORT TERM WEATHER PICTURE LOOKS LIKE A TALE OF TWO PATTERNS
CURRENTLY UNFOLDING ACROSS THE REGION. A WEAKENING FRONT STALLING
OUT NEAR KAUAI AND OAHU WILL CONTINUE TO PRODUCE SOUTHERLY WINDS
DRAWING UP ADDITIONAL UNSTABLE AND DEEP TROPICAL MOISTURE ACROSS
THE WESTERN HALF OF THE STATE. EXPECT CLOUDY SKIES, PERIODS OF
MODERATE TO LOCALLY HEAVY SHOWERS, AND ISOLATED THUNDERSTORMS FOR
THESE WESTERN ISLANDS THROUGH TONIGHT. MEANWHILE THE EASTERN
ISLANDS OF MAUI AND THE BIG ISLAND ARE UNDER THE MORE STABLE
INFLUENCE OF A WEAK HIGH PRESSURE RIDGE ALOFT, KEEPING A DRIER
SOUTHEASTERLY WIND REGIME IN PLACE. THE CENTRAL ISLANDS OF MOLOKAI
AND LANAI ARE CAUGHT IN BETWEEN THESE TWO DISTINCT WEATHER
PATTERNS, AND A MIX OF CLOUDS AND SCATTERED SHOWERS WILL CONTINUE.
THESE WESTERN WET WEATHER CONDITIONS WILL CONTINUE THROUGH
TONIGHT WITH IMPROVING WEATHER TRENDS OVER THE WESTERN ISLANDS
FROM THURSDAY ONWARD.
BY THURSDAY, THE HIGH PRESSURE RIDGE ALOFT WILL SLOWLY BUILD BACK
IN OVER THE ISLANDS AS THE TROUGH NORTH OF THE STATE FILLS IN AND
LIFTS NORTHWARD, HERALDING A RETURN STATEWIDE TO MORE STABLE
EASTERLY TRADE WIND WEATHER JUST IN TIME FOR THE WEEKEND. HOWEVER,
CLOUDS AND SHOWERS WILL LINGER OVER THE ISLANDS IN KAUAI COUNTY
FOR ONE MORE DAY AS THE TROUGH SLOWLY DRIFTS ACROSS THE ISLAND.
SUBSIDENCE TEMPERATURE INVERSION HEIGHTS WILL RANGE FROM AROUND
5,000 TO 7,000 FEET ELEVATION AS THE RIDGE BUILDS BACK IN,
LIMITING CLOUD HEIGHTS AND SHOWER POTENTIAL. THESE MORE TYPICAL
AND STABLE MODERATE TO BREEZY TRADE WINDS WITH BRIEF WINDWARD AND
MOUNTAIN SHOWERS WILL LAST THROUGH CHRISTMAS DAY.
IN THE EXTENDED RANGE OUTLOOK, ANOTHER COLD FRONT MAY APPROACH THE
HAWAIIAN ISLANDS FROM THE NORTHWEST A FEW DAYS AFTER CHRISTMAS,
POSSIBLY TRIGGERING YET ANOTHER ROUND OF WET WEATHER CONDITIONS.
STAY TUNED.
AVIATION
A WEAKENING COLD FRONT NEAR KAUAI AND A PREFRONTAL WIND
CONVERGENCE BOUNDARY NEAR OAHU WILL CONTINUE TO PRODUCE SOUTHERLY
WINDS, DRIVING UNSTABLE TROPICAL MOISTURE INTO THE WESTERN
ISLANDS OF NIIHAU, KAUAI AND OAHU THROUGH TONIGHT. EXPECT MVFR
CEILINGS WITH CLOUDY SKIES ALONG WITH PERIODS OF MODERATE TO HEAVY
SHOWERS AND ISOLATED THUNDERSTORMS. ISOLATED IFR CONDITIONS ARE
POSSIBLE IN THE HEAVIEST SHOWERS OR NEAR THUNDERSTORMS. GUSTY
WINDS WILL DEVELOP ALONG THE NORTHERN SLOPES OF EACH ISLAND DUE TO
THE SOUTHERLY WIND FLOW OVER THE ISLAND MOUNTAINS. THE EASTERN
HALF OF THE STATE WILL REMAIN FAIRLY STABLE AND DRY WITH
PREVAILING VFR CONDITIONS.
THE FRONT WILL WEAKEN INTO A TROUGH AS IT SLOWLY LIFTS NORTHWARD
BACK OVER KAUAI ON THURSDAY, AS A MID LEVEL RIDGE SLOWLY BUILDS
IN ACROSS THE STATE WITH IMPROVING WEATHER TRENDS LASTING INTO THE
WEEKEND AS EASTERLY TRADE WINDS GRADUALLY RETURN.
AIRMET SIERRA REMAINS IN EFFECT FOR TEMPO MOUNTAIN OBSCURATIONS
KAUAI, OAHU, AND MOLOKAI TODAY. IFR CONDITIONS OVER LANAI THIS
MORNING WILL LIKELY TRANSITION TO MOUNTAIN OBSCURATION AROUND 16Z.
MARINE
A COLD FRONT JUST NW OF KAUAI WATERS WILL DRIFT OVER KAUAI AND
STALL NEAR OAHU TONIGHT. MODERATE TO LOCALLY STRONG S WINDS WILL
HOLD OVER THE WESTERN HALF OF THE STATE AHEAD OF THE FRONT BEFORE
EASING TO LIGHT TO GENTLE SPEEDS TONIGHT AND THURSDAY. A SMALL
CRAFT ADVISORY (SCA) REMAINS IN EFFECT FOR STRONG WINDS AND SEAS
TO 10 FT THROUGH TONIGHT. ISOLATED THUNDERSTORMS AND HEAVY SHOWERS
REMAIN POSSIBLE MAINLY OVER KAUAI AND OAHU WATERS THROUGH
THURSDAY. A STRONG HIGH PRESSURE SYSTEM WILL BUILD N OF THE STATE
FRIDAY ALLOWING LIGHT TO MODERATE TRADES TO RETURN AND GRADUALLY
STRENGTHEN TO MODERATE TO STRONG SPEEDS SUNDAY INTO EARLY NEXT
WEEK.
A MODERATE, MEDIUM PERIOD N SWELL (350-360 DEGREE) WILL FADE TODAY
AS A MODERATE, SHORT TO MEDIUM PERIOD WNW SWELL (280 TO 320
DEGREES) FILLS IN. THIS SWELL WILL ELEVATE SURF ALONG NORTH AND
WEST FACING SHORES TO JUST BELOW THE HSA THRESHOLD AND WILL CREATE
FAIRLY CHOPPY CONDITIONS. SEAS WILL BUILD TO 10 FEET AND HIGHER
AROUND KAUAI AND OAHU WATERS. A LARGE, MEDIUM PERIOD NNW (330-350
DEGREE) SWELL WILL FILL IN TONIGHT AND PEAK THURSDAY RIGHT AROUND
ADVISORY LEVELS. THE SCA MAY NEED TO BE EXTENDED THROUGH FRIDAY
AND EXPANDED TO INCLUDE WINDWARD MAUI WATERS AS THIS SWELL WILL
KEEP SEAS ELEVATED. THIS SWELL WILL GRADUALLY FADE OUT THROUGH THE
REMAINDER OF THE WEEK WITH SMALL TO MODERATE N AND NW SWELLS
MIXED IN THROUGH THE WEEKEND.
E SHORE SURF WILL REMAIN SMALL EXCEPT WHERE NW-N SWELL ENERGY
WRAPS THROUGH THE WEEK. BY NEXT WEEK, A LARGE, SHORT PERIOD NE
SWELL COULD ELEVATE SURF ALONG E FACING SHORES AS STRONG TRADE
WINDS RETURN. S SHORE SURF WILL REMAIN CHOPPY AS PERSISTENT S-SW
WINDS HOLD THROUGH TODAY, BEFORE GRADUALLY EASING THROUGH THE
REST OF WEEK. SMALL BACKGROUND SW SWELLS WILL KEEP SURF FROM GOING
FLAT THROUGH THE WEEKEND.
FIRE WEATHER
WET WEATHER CONDITIONS AND ISOLATED THUNDERSTORMS WILL CONTINUE
THROUGH TONIGHT ACROSS NIIHAU, KAUAI AND OAHU. PERIODS OF CLOUDS
AND SCATTERED SHOWERS ARE EXPECTED FOR MOLOKAI AND LANAI. DRIER
CONDITIONS REMAIN OVER MAUI AND THE BIG ISLAND THROUGH TONIGHT.
TRADE WINDS AND STABILITY TRENDS WILL SLOWLY RETURN TO THE WESTERN
HALF OF THE STATE FROM FRIDAY INTO THE WEEKEND. WIND SPEEDS AND
HUMIDITY LEVELS WILL KEEP WEATHER CONDITIONS BELOW CRITICAL FIRE
THRESHOLDS OVER THE NEXT SEVEN DAYS.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR THE ISLANDS OF NIIHAU,
KAUAI AND OAHU.
SMALL CRAFT ADVISORY UNTIL 6 AM HST THURSDAY FOR WATERS AND
CHANNELS AROUND KAUAI AND OAHU.
DISCUSSION...BOHLIN
AVIATION...BOHLIN
MARINE...ALMANZA
FIRE WEATHER...BOHLIN
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