811
FXHW60 PHFO 151859
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
859 AM HST SUN MAR 15 2026
SYNOPSIS
HEAVY RAIN WILL CONTINUE OVER LEEWARD BIG ISLAND WHILE CONDITIONS
IMPROVE OVER THE WESTERN END OF THE STATE. WET WEATHER WILL
CONTINUE THROUGH THE WEEK.
SHORT TERM UPDATE
ISSUED AT 847 AM HST SUN MAR 15 2026
THE KONA LOW HAS LIFTED WELL NORTH OF THE AREA AND THE SURFACE LOW
IS APPROACHING 40N EARLY THIS MORNING. HOWEVER, THE ISLANDS REMAIN
ENVELOPED IN THE SOUTHERN PERIPHERY OF LARGE SCALE CYCLONIC FLOW
ALOFT WHICH ITSELF IS ANCHORED OVER THE CENTRAL NORTH PACIFIC. DEEP
MOISTURE IS REMAINS ESTABLISHED OVER AND UPSTREAM OF THE BIG ISLAND
WHILE DRY MID-LEVEL AIR IS WRAPPING IN FROM THE SOUTH OVER KAUAI.
THIS DRY AIR WAS EVIDENT IN THIS MORNING'S LIHUE SOUNDING WHICH
INDICATED WEAK CAPPING DEVELOPING AROUND 6KFT. FURTHER EAST, MORNING
SATELLITE AND RADAR REVEAL MEANINGFUL SHOWERS PERSISTING OVER
LEEWARD BIG ISLAND. STRONG SW FLOW WILL CONTINUE TO CAPITALIZE ON
OROGRAPHIC LIFT IN MAINTENANCE OF CONTINUED SHOWERS OVER THIS AREA
UNTIL THE NEXT WAVE OF DEEP MOISTURE ARRIVES THIS AFTERNOON. THIS
WILL REPRESENT ANOTHER OPPORTUNITY FOR HEAVY SHOWERS TO TRAIN OVER
THE LEEWARD AND POTENTIALLY SE SLOPES OF THE BIG ISLAND. IT IS
UNLIKELY TO BE AS INTENSE AS YESTERDAY AS LARGE SCALE LARGE SCALE
FORCING HAS WANED SUBSTANTIALLY, BUT ACTIVELY COOLING CLOUD TOPS
UPSTREAM NONETHELESS INDICATE POTENTIAL FOR DEEP CONVECTION AND
HEAVY RAINFALL CAPABLE OF PRODUCING FLASH FLOODING. CONFIDENCE IS
HIGH THAT THE FLOOD WATCH WILL REMAIN IN PLACE THROUGH TONIGHT FOR
THE BIG ISLAND. IT REMAINS UNCLEAR WHETHER THIS ACTIVITY WILL REACH
MAUI, BUT CURRENT TRENDS SUGGEST THAT MAY MISS TO THE SOUTH. IN THAT
CASE, CONSIDERATION WOULD BE GIVEN TO ENDING THE FLOOD WATCH FOR
THEM THIS AFTERNOON.
OVER THE WESTERN END OF THE STATE, AN UPPER WAVE PIVOTING OVER THE
AREA IS MAINTAINING WEAKLY CONVERGENT LOW-LEVEL FLOW CENTERED IN THE
KAUAI CHANNEL AT PRESS TIME. THIS CONVERGENCE COMBINED WITH WEAK
INSTABILITY IS ALLOWING A BAND OF DEEP BUT RELATIVELY LOW-INTENSITY
SHOWERS TO DEVELOP AND STREAM NORTHWARD OVER OAHU. INTRUDING DRY AIR
HAS SEEMINGLY ALREADY BROUGHT AN END TO THIS ACTIVITY OVER KAUAI.
THESE SHOWERS WILL GRADUALLY WORK EAST THROUGH TODAY REACHING
MOLOKAI LATE THIS EVENING IN A WEAKENING STATE AS FORCING PEELS OFF
TO THE NORTHEAST. GIVEN THE SATURATED GROUND, NUISANCE FLOODING IS
CERTAINLY PLAUSIBLE OVER OAHU DURING THE NEXT SEVERAL HOURS.
FINALLY, THE WIND ADVISORY WILL REMAIN IN PLACE THROUGH AT LEAST
NOON, BUT CURRENT OBSERVATIONS SUGGEST IT MAY BE A BIT TENUOUS,
ESPECIALLY IN LIGHT OF THE STEADILY WEAKENING BACKGROUND WIND
FIELD.
FOR THE SUMMITS, STRONG WINDS PERSIST AND THE HIGH WIND WARNING WILL
REMAIN IN PLACE. THE WINTER STORM WARNING LIKEWISE REMAINS IN PLACE,
THOUGH DEWPOINTS HAVE RISEN TO 33F AND RAIN IS CURRENTLY OBSERVED ON
THE SUMMITS. LITTLE CHANGE IN THE THERMAL PROFILE IS EXPECTED DURING
THE NEXT 24 HOURS, SO OBSERVED PTYPE TRENDS WILL DICTATE WHETHER THE
WSW WILL REMAIN IN PLACE THROUGH TONIGHT.
PREV DISCUSSION
A STRONG KONA STORM POSITIONED NORTH OF THE HAWAIIAN ISLANDS
CONTINUES TO GENERATE MODERATE TO HEAVY SHOWERS OVER THE EASTERN
HALF OF THE STATE, NAMELY MAUI AND THE BIG ISLAND. PERSISTENT
RAINFALL HAS RESULTED IN ISLAND-WIDE FLASH FLOOD WARNINGS ACROSS
THE BIG ISLAND, PERSISTING THROUGH THE MUCH OF THE MORNING.
MEANWHILE, CONDITIONS ACROSS THE WESTERN HALF OF THE STATE HAVE
BEGUN TO IMPROVE, ALLOWING SEVERAL PREVIOUSLY ISSUED HAZARD
PRODUCTS TO BE CANCELLED. HOWEVER, A NEW RAINBAND HAS DEVELOPED
AND MOVED OVER KAUAI, EXPECTED TO MOVE OVER OAHU LATER THIS
MORNING. LATEST GUIDANCE SUGGESTS A GRADUAL DEPICTS AN OVERALL
DOWNWARD TREND IN RAINFALL ACROSS THE HAWAIIAN ISLANDS WITHIN THE
NEXT 24 TO 36 HOURS, AS THE PRIMARY RAINBANDS SHIFT EAST OF THE
STATE BY EARLY MONDAY MORNING.
BASED ON THE LATEST OBSERVATIONS AND MODEL GUIDANCE, THE HIGH WIND
WARNING FOR MAUI COUNTY AND BIG ISLAND HAS BEEN DOWNGRADED TO A
WIND ADVISORY, WITH EXCEPTION OF THE SUMMITS OF BIG ISLAND AND
HALEAKALA ON MAUI. ADDITIONALLY, THE WIND ADVISORY ELSEWHERE WAS
EXTENDED FOR PORTIONS OF KAUAI AND OAHU, WHERE LOCALLY STRONG
WINDS OF 20 TO 30 MPH AND GUSTS UP TO 50 MPH ALONG WINDWARD
SLOPING AREAS. THE WIND ADVISORY WILL REMAIN IN EFFECT UNTIL 6 PM
HST THIS EVENING, TO BE REASSESSED WITH THE NEXT FORECAST CYCLE.
SHOWERY CONDITIONS ARE EXPECTED TO PERSIST INTO EARLY NEXT WEEK AS
THE KONA STORM WEAKENS AND SHIFTS NORTHEAST OF THE ISLANDS WITH
THE FINAL PUSH OF UPPER-LEVEL SUPPORT. AS THE SYSTEM DEPARTS,
WINDS ACROSS THE STATE WILL STEADILY DIMINISH AND THE COVERAGE OF
HEAVIER SHOWERS WILL DECREASE. HOWEVER, A LIGHT AND VARIABLE WIND
PATTERN IS ANTICIPATED TO DEVELOP, WHICH WILL MAINTAIN PERIODS OF
UNSETTLED WEATHER THROUGH MUCH OF THE UPCOMING WEEK.
THE EXTENDED FORECAST BEYOND MONDAY REMAINS SOMEWHAT UNCERTAIN AS
MODEL SOLUTIONS CONTINUE TO EVOLVE. CURRENT GUIDANCE INDICATES AN
UPPER-LEVEL TROUGHING PATTERN WILL PERSIST ACROSS THE REGION,
SUPPORTING LIGHT AND VARIABLE WINDS ALONG WITH PERIODIC SHOWERS
AND THE POTENTIAL FOR ISOLATED THUNDERSTORMS THROUGH THE REMAINDER
OF THE WEEK. TOWARD THE LATTER OF THE WEEK, SOME MODELS SUGGEST
BROAD HIGH PRESSURE MAY BEGIN TO BUILD OVER THE REGION,
POTENTIALLY ALLOWING TRADE WINDS TO RETURN. GIVEN THE UNCERTAINTY
AT THIS RANGE, FUTURE FORECAST UPDATES WILL REFINE THE EXPECTED
EVOLUTION OF THIS PATTERN.
AVIATION
ISSUED AT 852 AM HST SUN MAR 15 2026
LOW CIGS AND SHRA CONTINUE ACROSS THE ISLANDS. THIS ENTIRE SYSTEM
IS MOVING NORTHEASTWARD. A FEW ISOL TSTMS ARE POSSIBLE OVER THE
BIG ISLAND. AS FAR AS THE WINDS, THEY HAVE BEGUN TO WEAKEN
SLIGHTLY AND VEER MORE WEST-SOUTHWESTERLY OVER THE WESTERN END OF
STATE, BUT STILL REMAIN GUSTY IN SOME SPOTS ESPECIALLY OVER THE
WINDWARD PORTIONS OF THOSE ISLANDS. OVER MAUI AND THE BIG ISLAND,
BREEZY AND GUSTY WINDS ARE STILL POSSIBLE THROUGH TODAY.
AIRMET SIERRA IS IN EFFECT FOR MTN OBSC FOR ALL ISLANDS EXCEPT
KAUAI. AIRMET SIERRA FOR IFR IS NO LONGER IN EFFECT FOR THE BIG
ISLAND, BUT BRIEF AND ISOLATED IFR CONDITIONS ARE STILL POSSIBLE
TODAY.
AIRMET TANGO REMAINS IN EFFECT FOR MOD MID-UPPER LEVEL TURB
BETWEEN 130 AND FL330. IT IS IS ALSO IN EFFECT FOR TURB DOWNWIND
N THRU E OF TERRAIN STATEWIDE. CONDS SHOULD CONTINUE THIS MORNING
AND GRADUALLY IMPROVE WEST TO EAST.
LIGHT ICING IS POSSIBLE BETWEEN 130 AND FL260 AS MID-HIGH CLOUDS
CONTINUE MOVING THROUGH THE ISLANDS. THESE CONDS ARE EXPECTED TO
GRADUALLY IMPROVE TODAY.
MARINE
THE POWERFUL KONA STORM WILL WEAKEN AS IT MOVES NORTHEAST AND
AWAY FROM THE AREA DURING THE NEXT FEW DAYS, WITH CONDITIONS
IMPROVING OVER THE COASTAL WATERS. WINDS HAVE DROPPED BELOW GALE
FORCE OVER THE COASTAL WATERS, THEREFORE THE GALE WARNING HAS BEEN
CANCELLED AND REPLACED WITH A SMALL CRAFT ADVISORY (SCA), WHICH
IS IN EFFECT FOR ALL ZONES THROUGH 6 PM THIS EVENING. THE SCA MAY
NEED TO BE EXTENDED FOR PORTIONS OF THE WATERS AROUND THE BIG
ISLAND TONIGHT. WINDS WILL EASE BELOW ADVISORY LEVELS ACROSS ALL
WATERS BY MONDAY AND THEN REMAIN LIGHT AND VARIABLE TUESDAY AND
WEDNESDAY. RIDGING IS FORECAST TO STRENGTHEN NORTH OF THE ISLANDS
LATE IN THE WEEK, WHICH SHOULD BRING A RETURN OF MODERATE TO FRESH
TRADE WINDS.
STRONG SOUTHERLY WINDS WILL KEEP LARGE AND ROUGH SURF IN PLACE
ALONG SOUTH FACING SHORES TODAY, WITH THE SURF THEN TRENDING LOWER
TONIGHT AND MONDAY. A NEW LONG PERIOD SOUTH SWELL WILL ARRIVE
LATE MONDAY NIGHT AND TUESDAY, GIVING A NICE AND EXTENDED BOOST
TO SOUTH SHORE SURF THROUGH LATE NEXT WEEK.
A MODERATE SIZED SHORT-PERIOD WEST SWELL ASSOCIATED WITH THE KONA
STORM WILL AFFECT NORTH AND WEST FACING SHORES DURING THE NEXT
COUPLE DAYS, BUT SURF WILL REMAIN BELOW ADVISORY LEVELS. THE ONE
EXCEPTION IS OVER WEST FACING SHORES OF THE BIG ISLAND, WHERE
ADVISORY LEVEL SURF IS EXPECTED TODAY. AS A RESULT, A HIGH SURF
ADVISORY HAS BEEN ISSUED FOR WEST FACING SHORES OF THE BIG ISLAND
THROUGH 6 PM THIS EVENING. THE SHORT-PERIOD SWELL WILL LOWER
MONDAY NIGHT AND TUESDAY, WHILE A NEW MEDIUM-PERIOD NORTH-
NORTHWEST SWELL FILLS IN. THIS NORTH-NORTHWEST SWELL COULD BRING
SURF UP TO ADVISORY LEVELS TUESDAY NIGHT AND WEDNESDAY, WITH THE
SWELL THEN SHIFTING MORE NORTHERLY AND LOWERING BELOW ADVISORY
LEVELS THURSDAY INTO NEXT WEEKEND.
SURF ALONG EAST FACING SHORES WILL REMAIN WELL BELOW NORMAL LEVELS
THROUGH THE MIDDLE OF THE WEEK, BEFORE TRENDING UPWARD THURSDAY
INTO NEXT WEEKEND AS TRADE WINDS RETURN OVER AND UPSTREAM OF THE
ISLANDS.
HFO WATCHES/WARNINGS/ADVISORIES
WIND ADVISORY UNTIL 6 PM HST THIS EVENING FOR BIG ISLAND
INTERIOR-BIG ISLAND NORTH-BIG ISLAND SOUTH-BIG ISLAND SOUTHEAST-
CENTRAL OAHU-KAUAI EAST-KAUAI MOUNTAINS-KAUAI NORTH-KOHALA-KONA-
KOOLAU LEEWARD-KOOLAU WINDWARD-MAUI CENTRAL VALLEY NORTH-MAUI
WINDWARD WEST-MOLOKAI NORTH-MOLOKAI SOUTHEAST-MOLOKAI WINDWARD-
OAHU NORTH SHORE-OLOMANA-SOUTH MAUI/UPCOUNTRY-WAIANAE MOUNTAINS-
WINDWARD HALEAKALA.
FLOOD WATCH THROUGH LATE TONIGHT FOR BIG ISLAND EAST-BIG ISLAND
INTERIOR-BIG ISLAND NORTH-BIG ISLAND SOUTH-BIG ISLAND SOUTHEAST-
HALEAKALA SUMMIT-KAHOOLAWE-KIPAHULU-KOHALA-KONA-LANAI LEEWARD-
LANAI MAUKA-LANAI SOUTH-LANAI WINDWARD-MAUI CENTRAL VALLEY NORTH-
MAUI CENTRAL VALLEY SOUTH-MAUI LEEWARD WEST-MAUI WINDWARD WEST-
MOLOKAI LEEWARD SOUTH-MOLOKAI NORTH-MOLOKAI SOUTHEAST-MOLOKAI
WEST-MOLOKAI WINDWARD-SOUTH HALEAKALA-SOUTH MAUI/UPCOUNTRY-
WINDWARD HALEAKALA.
HIGH WIND WARNING UNTIL 6 PM HST THIS EVENING FOR BIG ISLAND
SUMMITS-HALEAKALA SUMMIT.
HIGH SURF ADVISORY UNTIL 6 PM HST THIS EVENING FOR KOHALA-KONA.
WINTER STORM WARNING UNTIL 6 AM HST MONDAY FOR BIG ISLAND
SUMMITS.
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS-
BIG ISLAND WINDWARD WATERS-KAIWI CHANNEL-KAUAI CHANNEL-KAUAI
LEEWARD WATERS-KAUAI NORTHWEST WATERS-KAUAI WINDWARD WATERS-
MAALAEA BAY-MAUI COUNTY LEEWARD WATERS-MAUI COUNTY WINDWARD
WATERS-OAHU LEEWARD WATERS-OAHU WINDWARD WATERS-PAILOLO CHANNEL.
DISCUSSION...PIERCE
AVIATION...DT
MARINE...JELSEMA
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