535
FXHW60 PHFO 191913
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
913 AM HST TUE MAY 19 2026
SYNOPSIS
AN UNSTABLE AND SOMEWHAT WET TRADE WIND PATTERN WILL CONTINUE
THROUGH TONIGHT, WITH BRIEF DOWNPOURS POSSIBLE. FROM WEDNESDAY
INTO EARLY NEXT WEEK, AN AREA OF HIGH PRESSURE NORTH OF THE
ISLANDS WILL PUSH DRIER AIR INTO THE REGION. TRADES ARE EXPECTED
TO BECOME WINDY BY THURSDAY AND FRIDAY, THEN WILL GRADUALLY EASE
BACK TO LOCALLY BREEZY LEVELS THIS WEEKEND.
SHORT TERM UPDATE
ISOLATED SHOWERS WERE MOVING WEST OVER MAINLY WINDWARD AND MAUKA
AREAS THIS MORNING, AND SKIES WERE PARTLY TO MOSTLY CLOUDY OVER
MOST OF THE STATE. WINDS WERE AVERAGING 5 TO 15 MPH WITH A FEW
HIGHER GUSTS IN THE USUAL WINDY SPOTS. WE EXPECT A FEW MODERATE TO
BRIEFLY HEAVY SHOWERS THIS AFTERNOON, BUT PROBABLY NOT AS HEAVY
AS YESTERDAY AS MOISTURE IS A LITTLE LOWER TODAY. ALL THIS IS
HANDLED WELL BY THE CURRENT FORECAST AND NO CHANGES ARE PLANNED AT
THIS TIME.
PREV DISCUSSION
ISSUED AT 341 AM HST TUE MAY 19 2026
EARLY THIS MORNING, LOCAL RADAR IMAGERY SHOWS JUST A FEW LIGHT
SCATTERED SHOWERS MOVING INTO THE ISLANDS ON LOCALLY BREEZY
EASTERLY TRADE WIND FLOW. SIMILAR TO THE DAY PRIOR, THE HEAVIER
SHOWERS THAT OCCURRED AT SELECT SPOTS YESTERDAY QUICKLY DIMINISHED
DURING THE LATE AFTERNOON AND EVENING, LEAVING ONLY LIGHT,
ISOLATED SHOWERS FAVORING WINDWARD AREAS OVERNIGHT. REGIONAL
SATELLITE IMAGERY EARLY THIS MORNING DOES SHOW A FEW BANDS OF
MOISTURE UPSTREAM OF THE STATE, HOWEVER, AND ALTHOUGH MOISTURE
CONTENT HAS DECREASED FROM THE PREVIOUS COUPLE OF DAYS, THE EARLY
MORNING 12Z SOUNDINGS FROM LIHUE AND HILO STILL SHOW AMPLE
PRECIPITABLE WATER AVAILABLE.
DRIER AIR IS FORECAST TO ARRIVE FROM TONIGHT INTO WEDNESDAY NIGHT
AS HIGH PRESSURE NORTH OF THE STATE STRENGTHENS. IN THE MEANTIME,
EXPECT A RELATIVELY WET TRADE WIND WEATHER PATTERN TO CONTINUE,
WITH MODERATE TO BRIEFLY HEAVY RAIN FROM SHOWERS THAT WILL
GENERALLY FAVOR WINDWARD AND MAUKA AREAS, AS WELL AS THE KONA
SLOPES OF THE BIG ISLAND DURING THE AFTERNOON.
FROM LATE WEDNESDAY ONWARD, PRECIPITABLE WATER VALUES ARE
ANTICIPATED TO DECREASE BACK DOWN TO AROUND 1 INCH, AND THIS DRIER
AIR WILL PERSIST INTO NEXT WEEK. INCREASED STABILITY AND STRONGER
TRADE WINDS ARE EXPECTED BY THURSDAY. LATEST GLOBAL GUIDANCE
REMAINS IN GOOD AGREEMENT WITH THE HIGH TO OUR NORTH
STRENGTHENING, WHICH SHOULD RESULT IN WINDY CONDITIONS ACROSS THE
REGION. WINDS COULD POTENTIALLY REACH WIND ADVISORY LEVELS
THURSDAY INTO FRIDAY FOR SOME AREAS, THEN DECREASING BACK TO
LOCALLY BREEZY LEVELS DURING THE SECOND HALF OF THE WEEKEND.
AVIATION
MODERATE TO LOCALLY FRESH TRADE WINDS WILL PERSIST TODAY AND
INCREASE ON WEDNESDAY AS THE ATMOSPHERE GRADUALLY BECOMES MORE
STABLE. PERIODS OF MVFR CONDITIONS WILL PRIMARILY AFFECT WINDWARD
MOUNTAIN AREAS, THOUGH AN ISOLATED HEAVY SHOWER COULD DEVELOP OVER
LEEWARD TERRAIN THIS AFTERNOON.
NO AIRMETS ARE IN EFFECT. WE WILL MONITOR FOR POTENTIAL MOUNTAIN
OBSCURATION ACROSS WINDWARD AREAS. INCREASING TRADE WINDS AND
STABILITY WILL EVENTUALLY REQUIRE AIRMET TANGO FOR LOW LEVEL
TURBULENCE OVER AND DOWNWIND OF TERRAIN.
MARINE
LOCALLY FRESH TRADES BECOME STRONG TO LOCALLY NEAR-GALES DURING
THE LATTER HALF OF THE WEEK. THE SMALL CRAFT ADVISORY (SCA)
REMAINS IN EFFECT AND WILL EVENTUALLY BE EXPANDED TO ALL WATERS AS
WINDS AND SEAS BUILD LATER THIS WEEK.
SMALL, SHORT TO MEDIUM PERIOD NNW SWELL WILL FILL IN TODAY. THIS
WILL BE FOLLOWED BY A SMALL NNW SWELL EMANATING FROM A STRONG LOW
NEAR THE ALEUTIAN ISLANDS BY LATE WEEK. A SERIES OF SMALL, LONG
PERIOD SSW SWELLS SUPPORTS NEAR-AVERAGE SURF ALONG S SHORES.
MEANWHILE, STRENGTHENING TRADES MAINTAIN ELEVATED SURF AND SHORT
PERIOD FRESH SWELL ALONG E FACING SHORES INTO NEXT WEEK.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST WEDNESDAY FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS-
MAALAEA BAY-PAILOLO CHANNEL.
DISCUSSION...VAUGHAN
AVIATION...WROE
MARINE...JVC
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