123
FXHW60 PHFO 041327
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
327 AM HST SUN OCT 4 2026
SYNOPSIS
MODERATE TRADES WILL CONTINUE THROUGH TUESDAY, BRINGING LIMITED
SHOWERS MAINLY WINDWARD AND MAUKA. AN UPPER LEVEL LOW WILL HELP
WEAKEN WINDS AND TURN THEM OUT OF THE SOUTHEAST WEDNESDAY, AND
SHOWERS WILL INCREASE AS MOISTURE INCREASES. HEAVY RAINFALL MAY
OCCUR LATE WEDNESDAY THROUGH FRIDAY.
DISCUSSION
ISOLATED SHOWERS WERE OCCURRING MAINLY WINDWARD AND MAUKA EARLY
THIS MORNING, AND TRADE WINDS WERE AVERAGING 5 TO 15 MPH WITH A
FEW GUSTS IN THE 20S. SKIES WERE PARTLY TO MOSTLY CLOUDY WINDWARD
AND MOSTLY CLEAR LEEWARD.
WE EXPECT A RELATIVELY DRY TRADE WIND REGIME TO CONTINUE THROUGH
MOST OF TUESDAY. SHOWERS WILL BE CONFINED MAINLY TO WINDWARD AND
MAUKA LOCATIONS. WIND SPEEDS WILL BE MODERATE, GENERALLY
AVERAGING 10 TO 20 MPH, WITH HIGHER GUSTS. LATE TUESDAY, THINGS
MAY GET MORE INTERESTING.
THE LATEST MODELS CONTINUE TO SHOW A STRONG UPPER LEVEL LOW
DEVELOPING TO OUR NORTHWEST LATE TUESDAY NIGHT AS A SHARP TROUGH
CUTS OFF. THIS WILL AID IN THE FORMATION OF A SURFACE LOW
APPROXIMATELY 900 MILES TO OUR NORTHWEST AND TURN OUR SURFACE
WINDS OUT OF THE SOUTHEAST. AS TROPICAL MOISTURE IS BROUGHT
NORTHWEST, PW VALUES WILL INCREASE TO AROUND 2" AND DEWPOINTS WILL
RISE TO AROUND 70 THURSDAY AND INTO THE LOWER 70S FRIDAY. AS THIS
DEEPER MOISTURE MOVES IN, HEAVY RAIN WILL BECOME LIKELY. THE EXACT
TRAJECTORY OF THIS MOISTURE IS NOT KNOWN WITH HIGH CONFIDENCE YET,
BUT AT THIS TIME IT APPEARS ALL THE ISLANDS WILL BE IMPACTED. IT
WILL TAKE A FEW MORE DAYS FOR THE MODELS TO CONVERGE ON THE
LOCATION AND EVOLUTION OF THE SURFACE LOW, AND THAT WILL HELP
DICTATE WHERE THE MOISTURE ADVECTION IS MAXIMIZED.
AVIATION
MODERATE TRADES THROUGH THE PERIOD. WINDWARD AND MAUKA SHRA
POSSIBLE. MVFR CONDS IN SHRA OTHERWISE VFR PREVAILS.
AIRMET SIERRA IS IN EFFECT FOR MTN OBSC FOR WINDWARD BIG ISLAND.
CONDS SHOULD IMPROVE IN THE MID MORNING HOURS.
MARINE
HIGH PRESSURE NORTH OF THE HAWAIIAN ISLANDS WILL PRODUCE MODERATE
TO LOCALLY FRESH TRADE WINDS THROUGH MONDAY. THE SMALL CRAFT
ADVISORY FOR THE WINDIER WATERS AND CHANNELS AROUND MAUI COUNTY
AND THE BIG ISLAND HAS BEEN EXTENDED THROUGH MONDAY AFTERNOON.
AFTER THIS POINT, HIGH PRESSURE TO THE NORTH BEGINS TO WEAKEN AND
TRADE WINDS WILL START TO DIMINISH. BY WEDNESDAY, TROUGHING
DEVELOPING NORTHWEST OF THE ISLANDS ARE INCREASINGLY LIKELY TO
CAUSE WINDS TO VEER OUT OF THE SOUTHEAST. THIS IS LIKELY TO BE
ACCOMPANIED BY INCREASED SHOWER ACTIVITY FOR THE LATTER HALF OF
THE WEEK.
SURF ALONG SOUTH-FACING SHORES WILL REMAIN BELOW AVERAGE TODAY.
FORERUNNERS FROM A NEW SMALL, LONG-PERIOD SOUTH SWELL ARRIVE TODAY AND
WILL SLOWLY FILL IN TONIGHT AND MONDAY, WITH A PEAK SLIGHTLY ABOVE
SEASONAL AVERAGES TUESDAY INTO WEDNESDAY. FOR THE LATTER HALF OF THE
WEEK, SURF NEAR OR SLIGHTLY BELOW AVERAGE WILL BE MAINTAINED BY THIS
FADING SWELL COMBINED WITH A MIX OF NEW, SMALL SOUTH SWELLS.
SURF ALONG NORTH-FACING SHORES BECOMES TINY TODAY BEFORE ANOTHER
SMALL, MEDIUM-PERIOD NORTHWEST SWELL ARRIVES TONIGHT AND PEAKS ON
MONDAY, PRODUCING A SMALL BUMP IN SURF LASTING INTO TUESDAY. SURF WILL
CONTINUE TO TREND UP FOR NORTH SHORES AS THIS WILL BE FOLLOWED BY A
SLIGHTLY LARGER LONG-PERIOD NORTHWEST SWELL THAT PEAKS ON WEDNESDAY.
SURF MAY APPROACH MODERATE LEVELS LATE WEEK AS MEDIUM-PERIOD NORTHWEST
SWELL ENERGY FURTHER INCREASES. SURF ALONG EAST FACING SHORES WILL
BE CHOPPY THROUGH MONDAY AS A RESULT OF EASTERLY TRADES.
A SMALL, LONG-PERIOD WEST SWELL ORIGINATING FROM TYPHOON CHOI-WAN
ALSO REACHES THE ISLANDS THURSDAY INTO THE WEEKEND, WHICH MAY PRODUCE
MODERATE SURF FOR WEST-FACING SHORES OF THE BIG ISLAND.
FIRE WEATHER
MODERATE TRADES WILL CONTINUE INTO TUESDAY AND DRIER AIR WILL
MOVE IN TODAY. RH VALUES ARE FORECAST TO HOVER JUST ABOVE THE
CRITICAL THRESHOLD FOR FIRE WEATHER EACH AFTERNOON THROUGH
TUESDAY. FIRE WEATHER RISK THEN DIMINISHES THROUGH THE REMAINDER
OF THE WEEK AS MOISTURE INCREASES, WINDS DECREASE, AND SHOWERS
INCREASE IN COVERAGE. THE INVERSION SHOULD RANGE FROM 6KFT TO 8KFT
THROUGH MONDAY.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST MONDAY FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS-
MAALAEA BAY-PAILOLO CHANNEL.
DISCUSSION...PARKER
AVIATION...WALSH
MARINE...QUESADA
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page