297
FXHW60 PHFO 180143
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
343 PM HST WED DEC 17 2025
SYNOPSIS
A STALLED COLD FRONT NEAR KAUAI WILL PRODUCE PERIODS OF MODERATE
TO LOCALLY HEAVY SHOWERS AND A FEW THUNDERSTORMS ACROSS THE
WESTERN PORTION OF THE STATE IN AN UNSTABLE SOUTHERLY WIND
PATTERN TONIGHT. MEANWHILE, MORE STABLE CONDITIONS ARE FORECAST
OVER THE EASTERN ISLANDS AS A WEAK RIDGE AND SOUTHEASTERLY WINDS
LIMIT SHOWER ACTIVITY. THE FRONT WILL WEAKEN INTO A TROUGH AND
LIFT NORTHWESTWARD BACK OVER KAUAI COUNTY ON THURSDAY, PROVIDING
CONTINUED SHOWER CHANCES OVER THE WESTERN END OF THE STATE, WITH
IMPROVING WEATHER TRENDS FOR MOLOKAI AND OAHU. RIDGING ALOFT WILL
THEN SLOWLY BUILD BACK IN OVER THE ISLANDS AS THE TROUGH NORTH OF
THE STATE FILLS IN AND LIFTS NORTHWARD, MARKING A RETURN OF MORE
STABLE EASTERLY TRADE WIND WEATHER THIS WEEKEND. THESE MORE
TYPICAL AND STABLE MODERATE TO BREEZY TRADE WINDS WITH BRIEF
WINDWARD AND MOUNTAIN SHOWERS WILL LAST THROUGH CHRISTMAS DAY.
DISCUSSION
AN ACTIVE WEATHER PATTERN CONTINUES ACROSS THE WESTERN PORTION OF
THE STATE THIS AFTERNOON AS A FRONT REMAINS STALLED NEAR KAUAI. A
MEANDERING BAND OF SHOWERS THUNDERSTORMS HAS BEEN MOVING OVER AND
NEAR KAUAI FOR MUCH OF THE DAY TODAY, BRINGING REPEATED ROUNDS OF
MODERATE TO LOCALLY HEAVY RAIN. RAIN GAUGES AND RADAR ESTIMATED
QPE SHOWS THAT PORTIONS OF KAUAI, IN PARTICULAR THE SOUTHERN AND
EASTERN PORTIONS OF THE ISLAND NEAR LIHUE AND SURROUNDING AREAS,
HAVE RECEIVED IN EXCESS OF 2 INCHES OF RAIN SINCE THIS MORNING.
WHEN COMBINED WITH RAINFALL THAT ALSO FELL LAST NIGHT AND DURING
THE EARLY MORNING HOURS, WIDESPREAD 24 HOUR RAINFALL TOTALS
BETWEEN 1 TO 3 INCHES HAVE BEEN MEASURED ACROSS THE GARDEN ISLE.
FORTUNATELY, DUE TO THE PROGRESSIVE NATURE OF THE HEAVIEST SHOWERS
WITHIN THE BAND OF MOISTURE, FLOODING HAS BEEN PREDOMINANTLY
LOCALIZED AND IMPACTS MINIMIZED THUS FAR IN THE EVENT. FOR OAHU,
SHOWERS HAVE BEEN FEWER THROUGHOUT THE DAY, THOUGH AREAS OF WEST
OAHU AND THE NORTH SHORE DID PICK UP DECENT RAINFALL TOTALS
EARLIER THIS MORNING. MUCH DRIER CONDITIONS ARE OBSERVED ACROSS
MAUI COUNTY AND THE BIG ISLAND, THOUGH TERRAIN- INFLUENCED GUSTY
SOUTHERLY FLOW HAS BEEN OBSERVED AT BOTH KAHULUI AND HILO THIS
AFTERNOON.
FROM THIS EVENING INTO THURSDAY, EXPECT CLOUDY SKIES, PERIODS OF
MODERATE TO LOCALLY HEAVY SHOWERS, AND A FEW THUNDERSTORMS TO
CONTINUE ACROSS KAUAI COUNTY, OAHU, AND SURROUNDING WATERS AS
UNSTABLE DEEP TROPICAL MOISTURE CONTINUES TO BE INTRODUCED OVER
THE WESTERN HALF OF THE STATE IN THE VICINITY OF THE STALLED
FRONTAL BOUNDARY AND IT'S ASSOCIATED PRE-FRONTAL CONVERGENCE.
OF NOTE, THE LATEST HI-RES AND PROBABILISTIC GUIDANCE, AS WELL AS
THE VARIOUS CONVECTION-ALLOWING MODELS (CAMS), CONTINUE TO
SUGGEST THAT BANDS OF POTENTIALLY TRAINING SHOWERS (HEAVY AT
TIMES) AND ISOLATED THUNDERSTORMS COULD MOVE OVER KAUAI AND/OR
OAHU THIS EVENING AND TONIGHT. CONFIDENCE IN EXACTLY WHERE THE
HEAVIEST, OR REPEATED, SHOWERS WILL SET UP IS FAIRLY LOW. WHILE
IT IS CERTAINLY POSSIBLE THAT THEY COULD REMAIN MOSTLY OVER THE
WATER IN THE KAUAI CHANNEL FOR THE MAJORITY OF THE NIGHT, IT IS
NEARLY EQUALLY PROBABLE THAT THEY COULD BEGIN TRAINING OVER THE
ISLANDS OF KAUAI OR OAHU DEPENDING ON THE FRONT'S PROGRESS,
POTENTIALLY LEADING TO FLASH FLOODING CONCERNS. THEREFORE, THE
FLOOD WATCH WILL CONTINUE THROUGH THURSDAY AFTERNOON.
BY LATER THURSDAY INTO FRIDAY, THE HIGH PRESSURE RIDGE ALOFT WILL
SLOWLY BUILD BACK IN OVER THE ISLANDS AS THE REMNANTS OF THE
FRONTAL BOUNDARY (NOW WEAKENED TO A TROUGH) NORTH OF THE STATE
FILLS IN AND LIFTS NORTHWARD. THIS WILL MARK THE RETURN OF MORE
STABLE EASTERLY TRADE WIND WEATHER 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.
INVERSION HEIGHTS WILL BE LIMITED AS THE RIDGE BUILDS BACK IN,
LIMITING CLOUD HEIGHTS, AND THEREFORE, SHOWER POTENTIAL. THESE
MORE TYPICAL AND STABLE MODERATE TO BREEZY TRADE WINDS WITH BRIEF
WINDWARD AND MOUNTAIN SHOWERS WILL LAST THROUGH CHRISTMAS DAY.
AVIATION
A WEAKENING COLD FRONT NEAR KAUAI AND A PREFRONTAL WIND
CONVERGENCE BOUNDARY OVER THE KAUAI CHANNEL WILL CONTINUE TO
PRODUCE SOUTHERLY WINDS AND DRIVE UNSTABLE TROPICAL MOISTURE
ACROSS THE WESTERN END OF THE STATE THROUGH THURSDAY. THE FRONT
WILL STALL NEAR OAHU OVERNIGHT INTO THURSDAY, THEN GRADUALLY
WEAKEN AND LIFT NORTHWARD BACK OVER KAUAI. MVFR CONDITIONS ARE
EXPECTED AS LOW CLOUDS, SHOWERS AND EVEN A FEW THUNDERSTORMS
ALONG AND AHEAD OF THE FRONT STREAM IN ACROSS THE WESTERN END OF
THE STATE. ISOLATED IFR CONDITIONS WILL REMAIN POSSIBLE IN THE
HEAVIER SHOWERS AND THUNDERSTORMS. THE EASTERN HALF OF THE STATE
WILL REMAIN FAIRLY STABLE AND DRY WITH PREVAILING VFR CONDITIONS.
AIRMET SIERRA REMAINS IN EFFECT FOR TEMPO MOUNTAIN OBSCURATIONS
ACROSS KAUAI AND OAHU THIS EVENING. IFR CONDITIONS OVER LANAI HAVE
PERSISTED THROUGH MOST OF THE DAY AND ARE EXPECTED TO CONTINUE
INTO THE EVENING.
AIRMET TANGO IS IN EFFECT FOR TEMPO MODERATE TURBULENCE BELOW 080
OVER AND NORTH THROUGH EAST OF ISLAND TERRAIN ON OAHU AND MOLOKAI.
THIS LOW LEVEL TURBULENCE SHOULD DECREASE OVERNIGHT.
MARINE
A COLD FRONT JUST NW OF KAUAI WILL SLOWLY DRIFT CLOSER AND STALL
NEAR OR OVER KAUAI TONIGHT BEFORE GETTING PUSHED BACK TO THE NW
TOMORROW. MODERATE TO LOCALLY STRONG SOUTHERLY WINDS OVER THE
WESTERN HALF OF THE STATE TONIGHT SHOULD GRADUALLY DECREASE TO
MODERATE BY THURSDAY MORNING. A SMALL CRAFT ADVISORY (SCA) REMAINS
IN EFFECT FOR SEAS TO 10 FT THROUGH THURSDAY NIGHT DUE TO THE
CURRENT WNW SWELL AND INCOMING NW SWELL. 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 TO LARGE, MEDIUM PERIOD WNW SWELL (280 TO 320 DEGREES)
AND NW SWELL HAVE COME IN ABOVE GUIDANCE AND WILL HOLD THROUGH
THE REST OF THE AFTERNOON BEFORE DECREASING LATE TONIGHT. THEN A
SLIGHTLY LARGER, MEDIUM PERIOD NNW (330-350 DEGREE) SWELL WILL
FILL IN LATE TONIGHT AND PEAK THURSDAY RIGHT AROUND ADVISORY
LEVELS. THESE SWELLS WILL KEEP ADVISORY LEVEL SURF IN PLACE FOR
NORTH AND WEST SHORES THROUGH THURSDAY AND WILL GRADUALLY DECLINE
FRIDAY. BY SATURDAY MORNING, A N SWELL LOOKS TO MOVE IN AND PEAK
AT AROUND ADVISORY LEVELS, THEN GRADUALLY DECREASE SUNDAY THROUGH
EARLY NEXT WEEK.
E SHORE SURF WILL REMAIN SMALL EXCEPT WHERE NW-N SWELL ENERGY
WRAPS THROUGH THE REST OF THE WEEK. BY NEXT WEEK, A LARGE, SHORT
PERIOD NE SWELL COULD ELEVATE SURF ALONG E FACING SHORES AS STRONG
TRADE WINDS RETURN. CURRENT MODEL DISCREPANCIES HIGHLIGHT
UNCERTAINTY IN THE TIMING OF THE HIGHER E SURF, WITH SOME MODELS
SHOWING LARGE SURF BY TUESDAY, WHILE OTHERS WEDNESDAY. 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
INTO THURSDAY ACROSS THE WESTERN ISLANDS. PERIODS OF CLOUDS AND
SCATTERED SHOWERS ARE EXPECTED FOR MOLOKAI AND LANAI, WITH DRIER
CONDITIONS REMAINING IN PLACE OVER MAUI AND THE BIG ISLAND. TRADE
WINDS AND INCREASINGLY STABLE CONDITIONS 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 THROUGHOUT THE NEXT WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH THURSDAY AFTERNOON FOR NIIHAU, KAUAI, AND OAHU.
HIGH SURF ADVISORY UNTIL 6 AM HST FRIDAY FOR NORTH AND WEST
FACING SHORES OF NIIHAU, KAUAI, AND OAHU.
HIGH SURF ADVISORY FROM 6 AM THURSDAY TO 6 AM HST FRIDAY FOR
NORTH AND WEST FACING SHORES OF MOLOKAI, AND NORTH FACING SHORES
OF MAUI.
SMALL CRAFT ADVISORY UNTIL 6 AM HST FRIDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-OAHU LEEWARD WATERS-KAIWI CHANNEL.
SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 AM HST FRIDAY
FOR MAUI COUNTY WINDWARD WATERS.
DISCUSSION...VAUGHAN
AVIATION...FARRIS
MARINE...TSAMOUS
FIRE WEATHER...VAUGHAN
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