471
FXHW60 PHFO 160144
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
344 PM HST SUN MAR 15 2026
SYNOPSIS
PERIODS OF MODERATE TO HEAVY RAIN CONTINUE OVER LEEWARD BIG ISLAND
AND MAUI WHILE CONDITIONS IMPROVE ELSEWHERE. THERE IS A THREAT FOR
HEAVY RAIN DURING THE LATTER HALF OF THIS WEEK AS LOW PRESSURE
DEVELOPS WEST OF THE ISLANDS.
DISCUSSION
MOISTURE EMBEDDED WITHIN DEEP LAYER SW FLOW EXTENDS WELL UPSTREAM OF
THE BIG ISLAND AND WILL CONTINUE TO DELIVER WAVES OF RAINFALL
THROUGH AT LEAST MONDAY NIGHT AND POTENTIALLY TUESDAY. HOWEVER, THE
LACK OF LARGE SCALE FORCING DURING THIS TIME WILL LIKELY RESULT IN A
TREND TOWARD LOWER INTENSITY RAINFALL COMPARED TO WHAT WAS OBSERVED
YESTERDAY OR EVEN TODAY. AT THE SAME TIME, THE WEAKENING BACKGROUND
WIND FIELD MAY ALLOW THE OVERNIGHT MOUNTAIN BREEZE TO MORE
EFFECTIVELY FOCUS STRONGER CONVECTION OFFSHORE AT NIGHT. RATHER
NONDESCRIPT SURFACE PRESSURE AND WIND FIELDS TAKES SHAPE DURING
TUESDAY WHICH SHOULD FINALLY BRING AN END TO THE STEADY STREAM OF
RAINFALL. AT THIS TIME, THE FLOOD WATCH WILL REMAIN IN EFFECT FOR
THE BIG ISLAND AND MAUI, THOUGH CONFIDENCE IN THE MOISTURE BAND
LIFTING SUFFICIENTLY FAR NORTH TO IMPACT MAUI AGAIN IS LOW AT THIS
TIME. THE WIND ADVISORY WILL END WITH ISSUANCE OF THE AFTERNOON
FORECAST PACKAGE, AND THE HIGH WIND WARNING FOR HALEAKALA AND THE
BIG ISLAND SUMMITS WILL BE EXTENDED THROUGH TONIGHT.
ATTENTION THEN TURNS TO MID TO LATE WEEK WHEN THE REMNANT FRONTAL
BAND REACTIVATES IN RESPONSE TO RENEWED MID/UPPER FORCING FOLLOWED
BY POTENTIAL DEVELOPMENT OF LOW PRESSURE WEST OF THE ISLANDS
DURING THE SECOND HALF OF THE WEEK. THE FIRST UPPER WAVE ARRIVES
LATE WEDNESDAY. MID- LEVEL FLOW WILL STILL BE SOUTHWESTERLY AT
THIS TIME, THOUGH IT IS UNCERTAIN WHETHER BOUNDARY LAYER FLOW WILL
WILL BE IN A STATE OF WEAK TRADES OF OUT OF THE SOUTH. IN ANY
CASE, AN UPTICK IN SHOWERS IS ANTICIPATED OVER THE ISLANDS BY
WEDNESDAY NIGHT. SURFACE PRESSURE FALLS WILL ALREADY BE TAKING
PLACE UPSTREAM OF THE ISLANDS DURING THIS TIME AS A TRAILING UPPER
WAVE APPROACHES THE ISLANDS FROM THE NORTHWEST. MODEL CONSENSUS
PREVIOUSLY BROKE DOWN AT THIS POINT WITH THE GFS INDICATING A
FLATTER AND MORE PROGRESSIVE SURFACE LOW WHILE THE EC INDICATED A
DEEPER AND SLOWER MOVING LOW. THE MOST RECENT RUN OF THE GFS HAS
MADE A STRONG MOVE TOWARD THE EC INCREASING CONFIDENCE THAT
ORGANIZED LOW PRESSURE WILL DEVELOP OVER OR NEAR THE ISLANDS BY
LATE THIS WEEK. MODERATE TO HEAVY RAIN THEN POTENTIALLY DEVELOPS
OVER THE ISLANDS AS EARLY AS FRIDAY AND WOULD CONTINUE INTO THE
WEEKEND.
AVIATION
SHOWERS CONTINUE OVER THE BIG ISLAND TODAY, AND A THIN BAND OF
MOISTURE CURRENTLY POSITIONED OVER MOLOKAI IS MOVING DOWN THE
ISLAND CHAIN, PROVIDING PERIODS OF LIGHT RAIN. EXPECT SHOWERS TO
CONTINUE FOR THE BIG ISLAND, PROVIDING MVFR TO ISOLATED AND BRIEF
IFR CONDITIONS. WINDS HAVE WEAKENED OVER THE WESTERN HALF OF THE
STATE, AND REMAINED OUT OF THE SW TODAY, BUT MAY VEER WSW LATER
TONIGHT. BREEZY S-SW WINDS ARE STILL EXPECTED FOR MAUI AND
LEEWARD BIG ISLAND THIS EVENING, BEFORE WEAKENING OVERNIGHT AND
INTO TOMORROW.
AIRMET SIERRA IS IN EFFECT FOR MTN OBSC FOR ALL ISLANDS EXCEPT
KAUAI. OAHU WILL LIKELY BE CLEAR OF MTN OBSC THIS EVENING. LATER
TONIGHT, IT IS POSSIBLE FOR ISLANDS FROM MOLOKAI TO MAUI TO SEE
IMPROVED CONDITIONS ONCE THE MOISTURE BAND PASSES. BIG ISLAND
WILL LIKELY REMAIN IN THIS AIRMET THROUGH TONIGHT.
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. THE MID-UPPER LEVEL TURB WILL
LIKELY CONTINUE THROUGH TONIGHT, AND THE TURBULENCE DOWNWIND OF
TERRAIN WILL LIKELY BE LIMITED TO THE EASTERN HALF OF THE STATE
TONIGHT.
LIGHT ICING IS POSSIBLE BETWEEN 130 AND FL260 AS MID-HIGH CLOUDS
CONTINUE MOVING THROUGH THE ISLANDS.
MARINE
THE KONA STORM THAT HAS IMPACTED THE REGION OVER THE PAST FEW DAYS
WILL WEAKEN AS IT MOVES NORTHEAST AND AWAY FROM THE AREA, WITH
CONDITIONS IMPROVING OVER THE COASTAL WATERS. LATEST HI-RES
GUIDANCE SHOWS THAT LOCALLY STRONG WINDS MAY LINGER OVER PORTIONS
OF THE CENTRAL AND EASTERN WATERS TONIGHT. ADDITIONALLY, BUOY
OBSERVATIONS SHOW THAT SEAS REMAIN ELEVATED, WITH BARBER'S POINT
AND HANALEI STILL REPORTING 10FT AND 12FT SIGNIFICANT WAVE
HEIGHTS THIS AFTERNOON, RESPECTIVELY. THEREFORE, THE SMALL CRAFT
ADVISORY (SCA) THAT WAS PREVIOUSLY IN EFFECT HAS BEEN EXTENDED IN
TIME THROUGH TONIGHT TO CAPTURE THE SEAS FOR THE WESTERN WATERS
AND LOCALLY BREEZY WINDS IN THE CENTRAL AND EASTERN WATERS (WITH
THE EXCEPTION OF THE SOUTHEAST BIG ISLAND ZONE WHERE THE SCA HAS
BEEN CANCELLED). BY EARLY MONDAY, BOTH WINDS AND SEAS ARE
EXPECTED TO FALL BELOW ADVISORY CRITERIA. WINDS WILL THEN REMAIN
LIGHT AND VARIABLE THROUGH MID-WEEK. RIDGING IS FORECAST TO
STRENGTHEN NORTH OF THE ISLANDS LATE IN THE WEEK, WHICH SHOULD
BRING A RETURN OF MODERATE TO FRESH TRADE WINDS.
LARGE, ROUGH SURF ALONG SOUTH-FACING SHORES THAT HAS BEEN
OBSERVED OVER THE PAST FEW DAYS WILL TREND LOWER TONIGHT AND
MONDAY AS WIND SPEEDS SUBSIDE. A NEW LONG-PERIOD SOUTH SWELL WILL
ARRIVE LATE MONDAY NIGHT AND TUESDAY, GIVING AN EXTENDED BOOST TO
SOUTH SHORE SURF THROUGH LATE THIS WEEK.
A MODERATE SIZED, SHORT-PERIOD WEST-NORTHWEST SWELL WILL CONTINUE
TO AFFECT NORTH AND WEST FACING SHORES THROUGH MONDAY, BUT SURF
WILL REMAIN BELOW ADVISORY LEVELS. THE ONE EXCEPTION IS FOR WEST
FACING SHORES OF THE BIG ISLAND, WHERE A HIGH SURF ADVISORY
REMAINS IN EFFECT THROUGH 6 AM HST. THIS 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
FLOOD WATCH THROUGH LATE TONIGHT FOR LANAI MAUKA-KAHOOLAWE-MAUI
WINDWARD WEST-MAUI LEEWARD WEST-HALEAKALA SUMMIT-KONA-KOHALA-BIG
ISLAND INTERIOR-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 WIND WARNING UNTIL 6 AM HST MONDAY FOR HALEAKALA SUMMIT-BIG
ISLAND SUMMITS.
HIGH SURF ADVISORY UNTIL 6 AM HST MONDAY FOR KONA-KOHALA.
SMALL CRAFT ADVISORY UNTIL 6 AM HST MONDAY FOR KAUAI NORTHWEST
WATERS-KAUAI WINDWARD WATERS-KAUAI LEEWARD WATERS-KAUAI CHANNEL-
OAHU WINDWARD WATERS-OAHU LEEWARD WATERS-KAIWI CHANNEL-MAUI
COUNTY WINDWARD WATERS-MAUI COUNTY LEEWARD WATERS-MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND WINDWARD WATERS-
BIG ISLAND LEEWARD WATERS.
DISCUSSION...JVC
AVIATION...DT
MARINE...VAUGHAN
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