561
FXHW60 PHFO 190643
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
843 PM HST MON MAY 18 2026
SYNOPSIS
AN UNSTABLE AND SOMEWHAT WET TRADE WIND PATTERN WILL CONTINUE
THROUGH TUESDAY NIGHT, WITH BRIEF DOWNPOURS POSSIBLE. FROM
WEDNESDAY INTO EARLY NEXT WEEK, AN AREA OF HIGH PRESSURE NORTH OF
THE ISLANDS WILL PUSH DRIER AIR THE REGION AND STRENGTHEN WINDS.
THE RESULT WILL BE A MODERATE TO BREEZY TRADE WIND PATTERN.
UPDATE
ISSUED AT 840 PM HST MON MAY 18 2026
SIMILAR TO YESTERDAY EVENING, THE HEAVY SHOWERS THAT OCCURRED AT
SELECT SPOTS DURING THE DAY HAVE DIMINISHED. ONLY LIGHT, ISOLATED
SHOWERS REMAIN EMBEDDED WITHIN MODERATE TO LOCALLY BREEZY TRADE
WINDS FAVORING WINDWARD AREAS. THE FORECAST REMAINS ON TRACK, SO
NO SIGNIFICANT UPDATES HAVE BEEN MADE THIS EVENING.
PREV DISCUSSION
ISSUED AT 328 PM HST MON MAY 18 2026
SHOWERS ACROSS WINDWARD AND MAUKA AREAS, ALONG WITH THE KONA
DISTRICTS ON BIG ISLAND, WERE NOTED ON RADAR THIS AFTERNOON. SOME
SHOWERS HAVE BEEN PRODUCING MODERATE TO BRIEFLY HEAVY RAIN, AND
THIS HAS RESULTED IN THE ISSUANCE OF FLOOD ADVISORIES ON KAUAI AND
ON BIG ISLAND. THESE SHOWERS WILL TREND DOWN AROUND SUNSET. WINDS
WERE AVERAGING 10 TO 20 MPH WITH GUSTS 20 TO 30 MPH.
CONDITIONS REMAIN ON THE HUMID SIDE THIS AFTERNOON AS WE AWAIT
DRIER AIR THAT SHOULD ARRIVE FROM TUESDAY NIGHT INTO WEDNESDAY
NIGHT. UNTIL THAT ARRIVES, WE WILL CONTINUE TO SEE RATHER WET
TRADES, MEANING WE WILL CONTINUE TO HAVE THE CHANCE FOR MODERATE
TO BRIEFLY HEAVY RAIN FROM SHOWERS. FROM LATE WEDNESDAY ONWARD, WE
WILL SEE NOTICEABLY LOWER PW VALUES (DOWN AROUND 1 INCH) GOING
ALL THE WAY INTO NEXT WEEK. ALOFT, AN UPPER LEVEL RIDGE WILL
BECOME ESTABLISHED TO OUR NORTH, EVEN AS WEAK TROUGHING WILL
EXTEND OFF THE SOUTHWEST COAST OF THE MAINLAND TOWARD HAWAII. THIS
TROUGHING WILL HAVE LITTLE TO NO IMPACT ON OUR SURFACE WEATHER,
AS THE UPPER RIDGING WILL HELP KEEP RELATIVELY DRY TRADES
ESTABLISHED OVER THE REGION. DEWPOINTS WILL FALL SEVERAL DEGREES
AS THE DRY AIR COMES IN, ALLOWING A LITTLE MORE COOLING OVERNIGHT
FOR WIND-SHELTERED AREAS.
AVIATION
ISSUED AT 840 PM HST MON MAY 18 2026
MODERATE TO LOCALLY BREEZY TRADES EXPECTED HOLD FOR THE NEXT
COUPLE DAYS. LOW CIGS AND SHRA WILL PRIMARILY IMPACT WINDWARD AND
MAUKA LOCATIONS WITH SOME LIMITED SPILLOVER TO LEEWARD AREAS. MVFR
CONDS POSSIBLE IN HEAVIER SHRA, OTHERWISE VFR PREVAILS.
AIRMET SIERRA IS IN EFFECT FOR MTN OBSC FOR WINDWARD KAUAI, MAUI
AND THE ENTIRE AREA OF THE BIG ISLAND.
MARINE
ISSUED AT 840 PM HST MON MAY 18 2026
THE PRESSURE GRADIENT BACK FROM A SURFACE HIGH CENTERED ABOUT
1,500 NAUTICAL MILES NORTHEAST OF THE ISLANDS REMAINS TIGHT
ENOUGH TO SUPPORT MODERATE TO LOCALLY FRESH TRADES THE NEXT COUPLE
OF DAYS. THE ANCHORED HIGH WILL EXPAND AND STRENGTHEN THROUGH MID
TO LATE WEEK. THE RESULTANT VERY TIGHT GRADIENT BACK ACROSS THE
CENTRAL PACIFIC WILL PRODUCE FRESH TO LOCALLY STRONG TO NEAR GALE
FORCE NEARSHORE WINDS THE LATER HALF OF THE WEEK. A SMALL CRAFT
ADVISORY (SCA) IS CURRENTLY IN EFFECT OVER THE WINDIER ZONES
SURROUNDING MAUI COUNTY AND BIG ISLAND. THE SCA WILL LIKELY BE
EXPANDED IN AREA LATER THIS WEEK TO ACCOUNT FOR MORE AREAWIDE
STRENGTHENED TRADES.
A SMALL SIZE, SHORT TO MEDIUM PERIOD NORTH NORTHWEST SWELL IS
EXPECTED TO FILL IN OVERNIGHT INTO TUESDAY. A GALE LOW SKIRTING
THE ALEUTIAN ISLANDS THE NEXT COUPLE OF DAYS WILL SEND THE TAIL
ENDS OF SMALL NORTH NORTHWEST SWELLS THROUGH LATE THIS WEEK.
A SERIES OF SMALL, LONG PERIOD SOUTH SOUTHWEST SWELLS WILL PROVIDE
NEAR SUMMER AVERAGE SIZE SURF ALONG SOUTH-FACING SHORES THROUGHOUT
THE WEEK. STRENGTHENING TRADES LATER THIS WEEK WILL KEEP SHORT
PERIOD, ELEVATED EASTERN WIND WAVE CHOP ALIVE WELL INTO THE
WEEKEND.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS-
MAALAEA BAY-PAILOLO CHANNEL.
SHORT TERM UPDATE...VAUGHAN
DISCUSSION...PARKER
AVIATION...BOHLIN
MARINE...BLOOD
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page