374
FXHW60 PHFO 181342
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
342 AM HST MON MAY 18 2026
SYNOPSIS
AN UNSTABLE AND SOMEWHAT WET TRADE WIND PATTERN WILL CONTINUE
THROUGH MID-WEEK, WITH BRIEF DOWNPOURS POSSIBLE. DURING THE SECOND
HALF OF THE WEEK, A STRENGTHENING AREA OF HIGH PRESSURE NORTH OF
THE ISLANDS WILL INCREASE STABILITY ACROSS THE REGION, PRODUCING
DRIER, BUT WINDIER CONDITIONS.
DISCUSSION
THIS MORNING, LOCAL SATELLITE AND RADAR IMAGERY SHOWS JUST A FEW
LIGHT SCATTERED SHOWERS MOVING INTO THE ISLANDS ON MODERATE
EASTERLY TRADE WIND FLOW. WHILE SOME AREAS OF THE STATE RECEIVED
SIGNIFICANT RAINFALL TOTALS YESTERDAY, SHOWER INTENSITY AND
COVERAGE EASED AREA-WIDE AFTER SUNSET. WITH THAT SAID, THE EARLY
MORNING SOUNDING FROM HILO CONTINUES TO SHOW OVER TWO INCHES OF
PRECIPITABLE WATER, COMPARED TO THE MUCH DRIER LIHUE SOUNDING.
BROAD TROUGHING ALOFT PERSISTS OVER THE ISLANDS, AND WITH THIS
AMOUNT OF AMPLE MOISTURE AVAILABLE, EXPECT THAT A GENERALLY WET
TRADE WIND PATTERN WILL CONTINUE FOR THE NEXT COUPLE OF DAYS WITH
FREQUENT SHOWERS OVER WINDWARD AREAS, ESPECIALLY FOR THE BIG
ISLAND. SOME SHOWERS COULD PRODUCE BRIEF DOWNPOURS, SIMILAR TO
THOSE THAT WERE OBSERVED THIS PAST WEEKEND AT TIMES. SHOWERS WILL
GENERALLY FAVOR WINDWARD AREAS DURING THE OVERNIGHT AND MORNING
HOURS, WITH SCATTERED LEEWARD SHOWERS DEVELOPING DURING THE
AFTERNOONS. ADDITIONALLY, DEWPOINTS WILL CONTINUE TO LINGER IN THE
UPPER 60S TO LOW 70S, WHICH SHOULD MAKE TEMPERATURES FEEL WARMER
THAN NORMAL.
INCREASED STABILITY AND STRONGER TRADE WINDS ARE EXPECTED BY
THURSDAY. LATEST GLOBAL GUIDANCE REMAINS IN GOOD AGREEMENT WITH A
STRONG HIGH DEVELOPING FAR NORTH OF THE STATE DURING THE SECOND
HALF OF THE WEEK, WHICH SHOULD RESULT IN WINDY CONDITIONS. WINDS
COULD POTENTIALLY REACH WIND ADVISORY LEVELS THURSDAY INTO FRIDAY
FOR SELECT AREAS DOWNSTREAM OF TERRAIN. DRIER CONDITIONS ARE ALSO
EXPECTED DURING THIS TIME, BUT SCATTERED SHOWERS EMBEDDED WITHIN
THE WINDY TRADE WIND FLOW WILL CONTINUE, ESPECIALLY DURING THE
NIGHT AND EARLY MORNING HOURS.
AVIATION
MODERATE TO LOCALLY BREEZY TRADES EXPECTED FOR THE NEXT COUPLE
DAYS. LOW CIGS AND SHRA SHOULD 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 KAUAI, OAHU, MAUI AND
WINDWARD SECTIONS OF THE BIG ISLAND.
MARINE
THE PRESSURE GRADIENT BACK FROM A SURFACE HIGH CENTERED ABOUT
1,400 NAUTICAL MILES NORTHEAST OF THE ISLANDS REMAINS TIGHT
ENOUGH TO SUPPORT MODERATE TO LOCALLY FRESH TRADES THE NEXT FEW
DAYS. THIS ANCHORED HIGH WILL STRENGTHEN AND EXPAND PAST MID WEEK.
THE RESULTANT TIGHTENING GRADIENT WILL PRODUCE FRESH TO LOCALLY
STRONG TRADES DURING THE LATER HALF OF THE WEEK.
A SMALL SIZE, SHORT TO MEDIUM PERIOD NORTH NORTHWEST (320-330
DEGREE) BUMP TONIGHT INTO EARLY TUESDAY WILL PROVIDE AN ADDITIONAL
FOOT OR TWO UPON NORTH-FACING SHORE SURF TUESDAY.
THE ARRIVAL OF A COUPLE OF MEDIUM TO LONG PERIOD SOUTH SOUTHWEST
(200 DEGREE) SWELLS THE NEXT FEW DAYS WILL MAINTAIN SEASONABLE
SURF ALONG SOUTHERN FACING SHORES. STRENGTHENING TRADES LATER
THIS WEEK WILL KEEP SHORT PERIOD, ELEVATED WIND WAVE CHOP ALIVE
GOING INTO THE WEEKEND.
WATER LEVELS PEAKING BETWEEN 2.5 TO 3.0 FT MLLW DURING TODAY'S HIGH
TIDES MAY RESULT IN SOME MINOR OVERWASH WITHIN LOW LYING COASTAL
AREAS.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 AM HST WEDNESDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...VAUGHAN
AVIATION...WALSH
MARINE...BLOOD
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page