599
FXHW60 PHFO 160106
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
306 PM HST MON DEC 15 2025
SYNOPSIS
A SURFACE TROUGH IS ORIENTED NE-SW ACROSS KAUAI COUNTY THIS
AFTERNOON, WITH THUNDERSTORMS FORMING AND MOVING TOWARD NIIHAU AND
KAUAI AS OF 2 PM HST. THIS TROUGH WILL MOVE WEST TONIGHT AND
REMAIN TO THE WEST TUESDAY. A NEW COLD FRONT WILL APPROACH FROM
THE NORTHWEST TUE NIGHT INTO WED, ADDING ITS MOISTURE AND
CONVERGENCE TO THE REMAINS OF THE INITIAL TROUGH AND MOVING BACK
SOUTHEAST TOWARD KAUAI COUNTY. THE MAIN AREA OF CONCERN FOR
POTENTIAL HEAVY RAIN FOR MID TO LATE-WEEK IS THEREFORE KAUAI AND
NIIHAU. THERE IS A CHANCE THAT THIS FEATURE COULD GET NEAR OAHU.
AFTER TRENDING AWAY FROM OAHU THE PAST COUPLE OF DAYS, THE VERY
LATEST GUIDANCE IS MOVING BACK TOWARD A HIGHER CHANCE OF IT
REACHING THE ISLAND.
DISCUSSION
SHOWERS AND THUNDERSTORMS WERE LOCATED IN THE KAUAI CHANNEL AND
OVER AND NEAR KAUAI AND NIIHAU THIS AFTERNOON. THESE WERE MOVING
NORTHEAST, AND HAVE A GOOD CHANCE TO IMPACT THE ISLAND THROUGH THE
REMAINDER OF THE AFTERNOON AND POSSIBLY IN THE EARLY EVENING.
SATELLITE IMAGES SHOW LOTS OF HIGH CLOUDS STREAMING NORTHEAST
ACROSS THE ENTIRE STATE, AND THIS IS EXPECTED TO CONTINUE INTO
TONIGHT.
MODELS STILL SHOW THE SURFACE TROUGH NEAR KAUAI/NIIHAU THIS
AFTERNOON (THE REMAINS OF AN OLD COLD FRONT) MOVING NORTH AND
WEST AWAY FROM THE STATE TONIGHT AND REMAINING THERE TUESDAY. A
NEW COLD FRONT WILL MOVE IN FROM THE NORTHWEST TUESDAY NIGHT,
PUSHING AN ENHANCED AREA OF MOISTURE AND CONVERGENCE TOWARD KAUAI
COUNTY. YESTERDAY THIS TIME, MODELS WERE TRENDING WEAKER WITH THIS
SYSTEM, SHOWING IT NOT MAKING IT MUCH FARTHER EAST THAN KAUAI.
HOWEVER, THE LATEST MODELS NOW INDICATE THAT IT COULD MAKE IT TO
OAHU, OR AT LEAST CLOSE ENOUGH TO INCREASE RAIN CHANCES THERE.
MODERATE TO HEAVY RAIN IN KAUAI COUNTY IS LIKELY WED-THU, AND IS
NOW LOOKING MORE POSSIBLE OVER/NEAR OAHU DURING THE SAME TIME
FRAME.
THE AREA OF MOISTURE RESULTING FROM THIS NEXT FRONT APPEARS TO GET
HUNG UP ALONG AN EAST-WEST AXIS NEAR OR JUST NORTH OF THE STATE BY
SATURDAY. A SURFACE HIGH PRESSURE SYSTEM TO OUR NORTHEAST IS THEN
FORECAST TO SEND A ROUND NORTHEAST TO EAST TRADES INTO THE STATE
THIS COMING WEEKEND, AND THIS WILL KEEP THE AREA OF MOISTURE
LINGERING OVER THE STATE RIGHT INTO EARLY NEXT WEEK. THERE IS LOTS
OF UNCERTAINTY CONCERNING HOW MUCH RAIN THERE WILL BE THIS
WEEKEND, BUT THERE APPEARS TO BE A RELATIVELY HIGH CHANCE OF
CLOUDS AND A MODERATE CHANCE AT CONTINUED SHOWERY CONDITIONS.
AVIATION
A SURFACE TROUGH NEAR KAUAI WILL LIFT NORTH WHILE RIDGING BUILDING
IN FROM THE SOUTHEAST WILL SLIGHTLY STRENGTHEN SOUTHERLY WINDS
ACROSS THE STATE THROUGH TUESDAY. NUMEROUS SHOWERS WITH POCKETS OF
HEAVY RAIN AND ISOLATED THUNDERSTORMS POSSIBLE ACROSS THE WESTERN
END OF THE STATE TONIGHT WITH THE THREAT DIMINISHING TUESDAY.
LIGHT ICING WILL BE POSSIBLE IN LAYERED CLOUDS (140-FL240) OVER
KAUAI AND OAHU TONIGHT.
AIRMET SIERRA POSTED FOR TEMPO IFR CONDITIONS ACROSS THE ENTIRETY
OF KAUAI, WHILE AIRMET SIERRA FOR TEMPO MOUNTAIN OBSCURATIONS FOR
OAHU, MOLOKAI AND LANAI CONTINUE TONIGHT.
AIRMET TANGO FOR TEMPO MODERATE TURBULENCE ALOFT FL240 TO FL340
ABOVE KAUAI AND OAHU ASSOCIATED WITH THE JET STREAM.
MARINE
WEAK SURFACE TROUGH IN THE VICINITY OF KAUAI AND OAHU APPEARS TO
HAVE DISSIPATED AS ANOTHER COLD FRONT ESTABLISHES IMMEDIATELY WEST
OF THE ISLANDS THIS EVENING INTO TONIGHT. THIS FRONT MAINTAINS A
CHANCE FOR ISOLATED THUNDERSTORMS OVER THE WESTERN NEARSHORE
WATERS THROUGH AT LEAST WEDNESDAY. LOCALLY FRESH S TO SW WINDS
EMERGE IN THE MEANTIME AS THE PARENT LOW DIGS SOUTH OF 30N. WINDS
THEN WEAKEN LATE THIS WEEK FOLLOWED BY RETURNING TRADES PERHAPS BY
SUNDAY.
THE PACIOOS WAIMEA BAY BUOY INDICATES SIGNIFICANT WAVE HEIGHTS ON
THE ORDER OF 10 FT AT PRESS TIME THIS AFTERNOON FAVORING AN UPWARD
ADJUSTMENT TO THE EXISTING FORECAST AND THE ISSUANCE OF A SMALL
CRAFT ADVISORY FOR SEAS FOR WATERS OVER THE CENTRAL AND EASTERN
PORTIONS OF THE STATE. SURF HAS PEAKED FOR KAUAI AND IS CURRENTLY
PEAKING OVER OAHU AT THE HIGH END OF THE HIGH SURF ADVISORY (HSA)
RANGE. IN ADDITION, REPORTS OF SURF IMPACTS PROMPTED HSA ISSUANCE
FOR W SHORES OF LEEWARD BIG ISLAND THIS AFTERNOON AS WNW (290-300)
SWELL BUILDS. SEAS HERE WILL BUILD THROUGH THE EVENING AND WILL
PEAK AT OR VERY NEAR THE HIGH SURF WARNING THRESHOLD TONIGHT.
OFFSHORE NDBC BUOYS AND THE NEARSHORE WAIMEA BUOY ALSO INDICATE AN
ONGOING TRANSITION TO A LARGE, LONG PERIOD N SWELL EMANATING FROM
LOW PRESSURE IN THE ALEUTIAN ISLANDS. THIS SWELL WILL MAINTAIN
ELEVATED SURF FOR N FACING AND OTHER SUSCEPTIBLE EXPOSURES
THROUGH TONIGHT AND HAVE PROMPTED THE EXTENSION OF THE HSA FOR
KAUAI AND OAHU THROUGH TONIGHT FOR N FACING SHORES ONLY. IN
ADDITION, N FACING SHORES OF THE BIG ISLAND WILL BE ADDED TO THE
HSA. ALL LOCATIONS ARE FORECAST TO DROP BELOW HSA THRESHOLDS BY
TUESDAY MORNING, THOUGH LEEWARD BIG ISLAND WILL BE WORTH
MONITORING FOR A POTENTIAL EXTENSION INTO TUESDAY. RENEWED ENERGY
OUT OF THE NW QUADRANT (300-320) WILL ELEVATE SURF NEAR THE HSA
THRESHOLD ONCE AGAIN EARLY WEDNESDAY THROUGH THURSDAY.
E SHORES REMAIN FLAT EXCEPT WHERE LONG PERIOD NW-N SWELL ENERGY
WRAPS. S SHORES EXPERIENCE SHORT PERIOD WIND WAVE SHOP AND S FRESH
SWELL ENERGY DUE TO PERSISTENT S-SW WINDS THROUGH THE WEEK.
FIRE WEATHER
LIGHT TO MODERATE WINDS AND HIGH RELATIVE HUMIDITY VALUES WILL
PREVENT THE STATE FROM HITTING CRITICAL FIRE WEATHER THRESHOLDS
OVER THE NEXT FEW DAYS.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH UNTIL 6 PM HST THIS EVENING FOR NIIHAU-KAUAI LEEWARD-
KAUAI MOUNTAINS-WAIANAE COAST-OAHU NORTH SHORE-OLOMANA-CENTRAL
OAHU-WAIANAE MOUNTAINS-KAUAI NORTH-KAUAI EAST-KAUAI SOUTH-EAST
HONOLULU-HONOLULU METRO-EWA PLAIN-KOOLAU WINDWARD-KOOLAU
LEEWARD.
HIGH SURF ADVISORY UNTIL 6 AM HST TUESDAY FOR NIIHAU-OAHU NORTH
SHORE-MAUI WINDWARD WEST-KONA-KOHALA-KAUAI NORTH-MOLOKAI
WINDWARD-MOLOKAI NORTH-MAUI CENTRAL VALLEY NORTH-WINDWARD
HALEAKALA-BIG ISLAND EAST-BIG ISLAND NORTH.
SMALL CRAFT ADVISORY UNTIL 6 AM HST TUESDAY FOR KAIWI CHANNEL-
MAUI COUNTY WINDWARD WATERS-ALENUIHAHA CHANNEL-BIG ISLAND
WINDWARD WATERS.
DISCUSSION...PARKER
AVIATION...FOSTER
MARINE...JVC
FIRE WEATHER...PARKER
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