371
FXHW60 PHFO 060135
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
335 PM HST MON JAN 5 2026
SYNOPSIS
A SURFACE TROUGH WEST OF KAUAI, ALONG WITH ITS PARENT UPPER LEVEL
LOW, WILL MOVE SOUTHWARD TODAY. THIS WILL CONTINUE THE THREAT OF
FLASH FLOODING AT LEAST OVERNIGHT AND POSSIBLY INTO TUESDAY. WINDS
WILL REMAIN MODERATE TO BREEZY OVERNIGHT BEFORE WEAKENING.
SIGNIFICANT SNOW AND ICE ACCUMULATIONS WERE ONGOING FOR THE BIG
ISLAND SUMMITS. THE UPPER LEVEL LOW IS EXPECTED TO WEAKEN OVER THE
NEXT TWO DAYS AS THE SURFACE TROUGH SHIFTS WEST OF THE STATE,
RESULTING IN REDUCED CHANCES OF THUNDERSTORMS AND HEAVY RAIN.
LIGHT WINDS WILL DEVELOP DURING THE SECOND HALF OF THE WEEK
ALLOWING FOR SEA BREEZES TO DEVELOP BUT SHOWERS WILL ONLY BE LIGHT
TO MODERATE.
DISCUSSION
AS OF 3 PM HST, SHOWERS WERE PLENTIFUL ON RADAR, ESPECIALLY OVER
THE BIG ISLAND AND KAUAI COUNTY. SKIES WERE MOSTLY CLOUDY AND
WINDS WERE MODERATE WITH WIDESPREAD COASTAL GUSTS OF 25 TO 35 MPH.
A FLOOD ADVISORY WAS IN EFFECT FOR MUCH OF WINDWARD BIG ISLAND,
AND OTHER ISLANDS WERE BEING CLOSELY MONITORED BUT WERE "WELL
BEHAVED" AT THIS TIME.
THE UPPER LEVEL LOW (AND ITS ASSOCIATED SURFACE TROUGH) LARGELY
RESPONSIBLE FOR OUR RECENT WET WEATHER IS LOCATED ABOUT 400 MILES
WEST OF KAUAI THIS AFTERNOON, AND IS FORECAST TO DRIFT SLOWLY SSE
OVERNIGHT AND TOMORROW. THIS WILL KEEP IT CLOSE ENOUGH TO CONTINUE
TO GIVE US AN UNSTABLE ATMOSPHERE CAPABLE OF SUPPORTING HEAVY
RAIN AND THUNDERSTORMS (ALTHOUGH THE REMAINING THUNDERSTORMS ARE
EXPECTED TO REMAIN OFF THE COAST TO OUR WEST). THEREFORE THE FLOOD
WATCH HAS BEEN EXTENDED THROUGH TUESDAY AFTERNOON. WINDS HAVE NOT
DEVELOPED ON THE PEAKS OF BIG ISLAND TO THE EXTENT FORECAST, SO
WE HAVE REDUCED THE HIGH WIND WARNING TO AN WIND ADVISORY THROUGH
TONIGHT. THE WINTER STORM WARNING THERE FOR SNOW/ICE WILL REMAIN
IN EFFECT OVERNIGHT.
AS THE UPPER LOW CONTINUES TO WEAKEN, IT WILL DRIFT SOUTHWEST
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT, BEFORE WEAKENING TOO MUCH
TO SIGNIFICANTLY IMPACT OUR WEATHER THURSDAY. OUR CHANCES OF RAIN
WILL DECREASE EACH DAY AS THIS OCCURS, WITH UPPER LEVEL RIDGING
PUSHING IN FROM THE WEST TO FURTHER STABILIZE THE ATMOSPHERE.
FRIDAY AND SATURDAY, WEAK RIDGING ALOFT WILL KEEP US RELATIVELY
DRY AND COOL, WITH NO SIGNIFICANT WEATHER EXPECTED. WITH LIGHTER
WINDS, WE WILL SEE A SHIFT TO SEA- AND LAND-BREEZES THAT WILL HELP
ALTER PRECIPITATION PATTERNS AWAY FROM THE TYPICAL TRADE WIND
(WINDWARD AND MAUKA WET/LEEWARD DRY) PATTERN.
SUNDAY INTO MONDAY, LONG RANGE MODELS SHOW THE POTENTIAL FOR AN
UPPER LEVEL TROUGH TO PUSH A SURFACE BOUNDARY THROUGH THE STATE.
IF THIS WERE TO OCCUR, IT WOULD BRING A PERIOD OF SHOWERS AND
NORTHWEST SURFACE WINDS. MORE DETAIL WILL EMERGE AS WE GET CLOSE
IN TIME.
AVIATION
A TROUGH WEST OF THE STATE WILL CONTINUE TO PRODUCE UNSETTLED
WEATHER TONIGHT INTO TUESDAY. PREVAILING MVFR CONDITIONS WILL BE
COMMON ALONG NORTH THROUGH EAST SECTIONS OF THE ISLANDS AS BREEZY
TO STRONG EAST-SOUTHEAST SURFACE WINDS BRING PERIODS OF RAIN,
FAVORING PRIMARILY EAST AND SOUTHEAST FACING SLOPES AND COASTS.
SOME SHOWERS COULD BE HEAVY AT TIMES, PRODUCING BRIEF IFR
CONDITIONS, AND A FLOOD WATCH REMAINS IN EFFECT STATEWIDE THROUGH
6 AM HST TUESDAY.
CONDITIONS ARE EXPECTED TO GRADUALLY IMPROVE BY TUESDAY, THOUGH
SOME LINGERING SHOWERS WILL REMAIN POSSIBLE, PARTICULARLY FOR THE
WESTERN END OF THE STATE.
AIRMET SIERRA REMAINS IN EFFECT FOR MOUNTAIN OBSCURATION OVER
WINDWARD AREAS OF ALL ISLANDS. THESE CONDITIONS WILL LIKELY
PERSIST THROUGH THE NIGHT. ADDITIONALLY, AIRMET TANGO REMAINS IN
EFFECT FOR BOTH MID- AND UPPER-LEVEL TURBULENCE, WHICH WILL
LIKELY PERSIST THROUGH THE NIGHT AS WELL. ELLROD GUIDANCE SHOWS
THAT SOME SEVERE TURBULENCE COULD DEVELOP NEAR KAUAI BY EARLY
TUESDAY, SO INTERESTS SHOULD CONTINUE TO MONITOR FOR POTENTIAL
SIGMETS RELATING TO UPPER TURBULENCE CLOSER TO THE ISLANDS.
FINALLY, AIRMET ZULU REMAINS IN EFFECT FOR MODERATE RIME ICING
ACROSS THE ENTIRE STATE.
MARINE
A TROUGH WEST OF HAWAII WILL CONTINUE SHOWERS AND POSSIBLE
THUNDERSTORMS WINDING DOWN BY MIDWEEK. STRONG EAST TO SOUTHEAST
WINDS WILL IMPACT ALL WATERS THROUGH TUESDAY AND PRODUCE ROUGH
SEAS. A SMALL CRAFT ADVISORY FOR BOTH WINDS AND SEAS REMAINS IN
EFFECT FOR THE ALL COASTAL WATERS THROUGH TUESDAY NIGHT. WIND AND
SEA CONDITIONS WILL IMPROVE MID TO LATE THIS WEEK AS THE
DISTURBANCE MOVES FURTHER WEST AND AWAY FROM THE ISLANDS.
A MODERATE, MEDIUM PERIOD, NORTH NORTHEAST (030-040 DEGREE) SWELL
WILL VEER MORE EASTERLY AND DECLINE TONIGHT. THE NEXT SMALL, LONG
PERIOD, NORTHWEST (310 DEGREE) SWELL WILL BUILD LATE TUESDAY AND
HOLD THROUGH FRIDAY, THEN RISE THIS WEEKEND WITH A NEW NORTH
NORTHWEST SWELL (330 DEGREE) LIKELY PRODUCING WARNING SURF ALONG
EXPOSED NORTH AND WEST FACING SHORES.
A HIGH SURF ADVISORY REMAINS IN EFFECT FOR EXPOSED EAST FACING
SHORES THROUGH TUESDAY NIGHT DUE TO AN EASTERLY SWELL GENERATED BY
THE LOCAL AND UPSTREAM EAST WINDS. SURF WILL DROP THROUGH THE
REMAINDER OF THE WEEK AS WINDS TAPER OFF.
THE COASTAL FLOOD STATEMENT WILL CONTINUE THROUGH LATE TONIGHT.
EXPECT MINOR FLOODING OF LOW LYING COASTAL AREAS DURING THE EARLY
MORNING HIGH TIDES.
HFO WATCHES/WARNINGS/ADVISORIES
FLOOD WATCH THROUGH LATE TONIGHT FOR NIIHAU-KAUAI LEEWARD-KAUAI
MOUNTAINS-WAIANAE COAST-OAHU NORTH SHORE-OLOMANA-CENTRAL OAHU-
WAIANAE MOUNTAINS-LANAI MAUKA-KAHOOLAWE-MAUI WINDWARD WEST-MAUI
LEEWARD WEST-HALEAKALA SUMMIT-KONA-KOHALA-BIG ISLAND INTERIOR-
KAUAI NORTH-KAUAI EAST-KAUAI SOUTH-EAST HONOLULU-HONOLULU METRO-
EWA PLAIN-KOOLAU WINDWARD-KOOLAU LEEWARD-MOLOKAI-LANAI WINDWARD-
LANAI LEEWARD-LANAI SOUTH-MAUI CENTRAL VALLEY NORTH-MAUI CENTRAL
VALLEY SOUTH-WINDWARD HALEAKALA-KIPAHULU-SOUTH MAUI/UPCOUNTRY-
SOUTH HALEAKALA-BIG ISLAND SOUTH-BIG ISLAND SOUTHEAST-BIG ISLAND
EAST-BIG ISLAND NORTH.
HIGH SURF ADVISORY UNTIL 6 AM HST WEDNESDAY FOR OLOMANA-KAUAI
EAST-KAUAI SOUTH-EAST HONOLULU-KOOLAU WINDWARD-MOLOKAI WINDWARD-
MOLOKAI SOUTHEAST-WINDWARD HALEAKALA-KIPAHULU-SOUTH HALEAKALA-
BIG ISLAND SOUTHEAST-BIG ISLAND EAST-BIG ISLAND NORTH.
WINTER STORM WARNING UNTIL 6 AM HST TUESDAY FOR BIG ISLAND
SUMMITS.
WIND ADVISORY UNTIL 6 AM HST TUESDAY FOR BIG ISLAND SUMMITS.
SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR ALL HAWAIIAN
WATERS-
DISCUSSION...PARKER
AVIATION...VAUGHAN
MARINE...FOSTER
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