059
FXHW60 PHFO 231338
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
338 AM HST THU APR 23 2026
SYNOPSIS
A SURFACE RIDGE BUILDING NORTH OF THE ISLANDS WILL ALLOW MODERATE
TRADE WINDS TO RETURN TO THE ISLANDS TODAY. RAINFALL WILL BE
LIMITED INTO THE WEEKEND DUE TO AN UPPER LEVEL RIDGE OVER THE
ISLANDS. HOWEVER LOW LEVEL MOISTURE RIDING IN ON THE TRADES WILL
BRING MORE TYPICAL WINDWARD AND MAUKA SHOWERS BY THE END OF THE
WEEKEND.
DISCUSSION
IN THE VERY SHORT TERM, WE ARE IN CLOSE CONTACT WITH THE HAWAIIAN
VOLCANO OBSERVATORY WITH REGARDS TO KILAUEA'S EPISODE 45 ERUPTION
WHICH BEGAN NOT LONG AFTER MIDNIGHT. AN ASHFALL ADVISORY WAS
RECENTLY ISSUED FOR VOLCANIC DEBRIS THAT MAY BE REACHING AREAS TO
THE SOUTH TO SOUTHWEST OF THE VOLCANO.
OTHERWISE, NO SIGNIFICANT CHANGE TO THE FORECAST WITH THE MORNING
PACKAGE. THE POPS AND SUPPORTING GRIDS HAVE BEEN NUDGED TO THE
LATEST NATIONAL BLEND OF MODELS PACKAGE.
A LOW PRESSURE SYSTEM ROUGHLY 700 MILES EAST-NORTHEAST OF THE
ISLANDS, COMBINED WITH LOW ABOUT 1000 MILES NORTH-NORTHWEST OF
THE ISLANDS ARE HELPING TO DISRUPT THE TRADE WIND FLOW. HOWEVER
THE LOW THE EAST-NORTHEAST WILL CONTINUE TO WEAKEN TODAY AS IT
MOVES TO THE EAST AWAY FROM THE ISLANDS. AND THE LOW TO THE
NORTH-NORTHWEST WILL LIFT TO THE NORTH. AS THIS HAPPENS TODAY, THE
RIDGE TO THE NORTH WILL STRENGTHEN, AND MODERATE TRADES WILL
FILTER BACK OVER THE ISLANDS. THE GLOBAL MODELS AGREE ON MID
LEVEL RIDGING OVER THE REGION WHICH WILL HELP TO MAINTAIN A STABLE
AIRMASS, THEREBY LIMITING RAINFALL TOTALS OVER THE NEXT FEW DAYS.
THE GLOBAL MODELS ARE IN GOOD AGREEMENT THAT MOISTURE FROM THE
ABOVE MENTIONED LOW WILL GET CAUGHT UP IN THE TRADE WIND FLOW OVER
THE WEEKEND, AND LATE IN THE WEEKEND, MAKE ITS WAY INTO THE
ISLANDS. THIS WILL HELP US RETURN TO A MORE TYPICAL TRADE WIND
WEATHER PATTERN WITH SOME SHOWERS OVER THE WINDWARD AND MAUKA
AREAS, ALONG WITH THE CLOUDS AND SHOWERS THAT FORM OVER THE KONA
SLOPES DURING THE AFTERNOON.
AVIATION
MODERATE NORTHEASTERLY TRADE WINDS WILL FOCUS MOST SHOWERS OVER
WINDWARD AND MOUNTAIN AREAS OVER THE NEXT SEVERAL DAYS. VFR
CONDITIONS WILL PREVAIL WITH BRIEF MVFR CONDITIONS ANY IN SHOWERS.
NO AIRMETS IN EFFECT.
WITH AN ERUPTION OF KILAUEA UNDERWAY, INCREASED HAZE AND ASH
AROUND THE SOUTHERN HALF OF THE BIG ISLAND IS HIGHLY LIKELY.
SIGMET SERIES YANKEE IS IN PLACE WITH ESTIMATED ASH TOPS AT FL250.
MARINE
TRADE WINDS WILL BE MAKING A COME BACK TODAY IN RESPONSE TO AN
UPPER RIDGE EVER SO SLOWLY EXPANDING IN FROM WEST NORTHWEST OF
THE ISLANDS. THE ASSOCIATED SURFACE HIGH FAR NORTHWEST OF THE
OFFSHORE WATERS WILL TRAVEL EAST, PASS NORTH OF THE LOCAL WATERS
AND BE NORTHEAST OF THE AREA BY EARLY NEXT WEEK. THIS WILL PRODUCE
A TIGHT ENOUGH CENTRAL PACIFIC PRESSURE GRADIENT OVER THE ISLANDS
TO MAINTAIN MODERATE TO LOCALLY FRESH TRADE WIND MAGNITUDES THE
NEXT SEVERAL DAYS. TRADES WILL PERSIST THROUGH THE WEEKEND AS
ANOTHER HIGH PASSES NORTH OF THE STATE. BRIEF PERIODS OF LOCALLY
STRONG WINDS WILL BE POSSIBLE THIS WEEKEND ACROSS THE WINDIER
CHANNELS AND BAYS SURROUNDING MAUI COUNTY AND BIG ISLAND.
A SMALL, SHORT TO MEDIUM PERIOD NORTHWEST SWELL THAT PEAKED
YESTERDAY WILL GRADUALLY LEVEL OUT THE NEXT FEW DAYS. A PAIR OF
NORTH PACIFIC GALE LOWS WILL SEND A SERIES OF SMALL NORTH TO
NORTHWEST SWELLS DOWN INTO THE LOCAL WATERS FROM FRIDAY NIGHT
THROUGH THE FIRST HALF OF NEXT WEEK. THESE SWELLS WILL MAINTAIN
WAIST TO HEAD HIGH SURF ALONG NORTH-FACING SHORES INTO NEXT WEEK.
AN OVERLAPPING SMALL, SHORT TO MEDIUM PERIOD NORTH NORTHEAST
SWELL THAT PEAKED YESTERDAY AFTERNOON INTRODUCED ADVISORY LEVEL
SURF ALONG MANY NORTHEAST TO EASTERN EXPOSURES, AS WELL AS
ELEVATING SURF TO ABOVE AVERAGE HEIGHTS ALONG SELECT MAUI AND BIG
ISLAND WESTERN SHORES. THIS SWELL HAS LEVELED OUT AND FALLEN
BELOW LEVELS THAT WILL NOT PRODUCE ADVISORY LEVEL SURF. THEREFORE,
THE HIGH SURF ADVISORY FOR EAST FACING SHORES HAS BEEN CANCELLED.
AN ENHANCED NORTHEAST FETCH IN THE PROXIMITY OF A VICINITY WEAK LOW
NORTHEAST OF THE ISLANDS WILL PUSH IN A SECONDARY SWELL TOMORROW.
MODERATE TO FRESH TRADES WILL ALSO SUPPORT NEAR SEASONAL AVERAGE
EAST-FACING SHORE WIND WAVE SURF.
SMALL BACKGROUND ENERGY FROM THE WEST WILL CONTINUE TO LINGER THE
NEXT FEW DAYS AND FADE OUT THIS WEEKEND. A SMALL SOUTHWEST BUMP
FROM TASMAN SEA GALE ENERGY THAT PASSED ACROSS AMERICAN SAMOA'S
51209 BUOY YESTERDAY IS EXPECTED TO ARRIVE THIS WEEKEND. NO
SIGNIFICANT SOUTH SWELLS ARE EXPECTED THROUGH THE FIRST HALF OF
NEXT WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
ASHFALL ADVISORY UNTIL 10 AM HST THIS MORNING FOR BIG ISLAND
SOUTH-BIG ISLAND SOUTHEAST.
DISCUSSION...M BALLARD
AVIATION...TSAMOUS
MARINE...BLOOD
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