382
FXHW60 PHFO 041907
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
907 AM HST SUN OCT 4 2026
SYNOPSIS
BREEZY 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 INTO NEXT WEEKEND.
DISCUSSION
HIGH PRESSURE NORTH OF HAWAII AND A WEAK DISTURBANCE PASSING SOUTH
OF THE AREA WILL RESULT IN BREEZY TRADE WINDS AND STABLE WEATHER THROUGH
MONDAY. SCATTERED LOW CLOUDS AND ISOLATED SHOWERS WILL MOVE THROUGH
THE TRADE WIND FLOW AND PRIMARILY IMPACT WINDWARD SLOPES, BUT
RAINFALL ACCUMULATIONS WILL REMAIN LIGHT.
WINDS WILL WEAKEN AND VEER SOUTHEASTERLY BY LATE TUESDAY, AND
SOUTH BY WEDNESDAY, AS A SHARP TROUGH APPROACHES FROM THE
NORTHWEST. A SURFACE LOW WILL FORM ALONG THE TROUGH AND THE
SOUTHERLY WINDS WILL DRAW DEEP TROPICAL MOISTURE OVER THE ISLANDS
FROM WEDNESDAY NIGHT OR THURSDAY THROUGH NEXT WEEKEND. PW VALUES
WILL INCREASE TO AROUND 2 INCHES 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 WILL CONTINUE THROUGH MONDAY WITH ISOLATED
SHOWERS ACROSS WINDWARD AND MOUNTAIN AREAS WHERE SHORT-LIVED MVFR
CONDITIONS ARE POSSIBLE.
OTHERWISE, VFR CONDITIONS WILL PREVAIL ACROSS THE STATE THROUGH
AT LEAST MONDAY.
AIRMET SIERRA FOR MOUNTAIN OBSCURATION WILL BE CANCELLED AS
CONDITIONS HAVE IMPROVED ON THE BIG ISLAND.
MARINE
HIGH PRESSURE NORTH OF THE HAWAIIAN ISLANDS WILL PRODUCE FRESH TO
LOCALLY STRONG 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 WEAKENS AND TRADES WILL START TO DIMINISH.
BY WEDNESDAY, TROUGHING DEVELOPING NORTHWEST OF THE ISLANDS IS
INCREASINGLY LIKELY TO CAUSE WINDS TO VEER OUT OF THE SOUTHEAST AND
BRING INCREASED SHOWER ACTIVITY FOR THE LATTER HALF OF THE WEEK.
SURF ALONG SOUTH-FACING SHORES WILL REMAIN BELOW AVERAGE TODAY. A
NEW SMALL, LONG-PERIOD SOUTH SWELL WILL SLOWLY FILL IN TONIGHT AND
MONDAY, WITH A PEAK SLIGHTLY ABOVE AVERAGE TUESDAY INTO WEDNESDAY.
NEAR OR SLIGHTLY BELOW AVERAGE SURF WILL HOLD THROUGH THE REST OF
THE WEEK BE MAINTAINED BY A MIX OF NEW, SMALL SOUTH SWELLS.
A SMALL, MEDIUM-PERIOD NORTHWEST SWELL WILL ARRIVE TONIGHT AND PEAK
MONDAY, PRODUCING A SMALL BUMP IN SURF THROUGH TUESDAY. SURF WILL
CONTINUE TO TREND UP FOR NORTH SHORES AS A SLIGHTLY LARGER LONG-PERIOD
NORTHWEST SWELL PEAKS WEDNESDAY. SURF MAY APPROACH MODERATE LEVELS
LATE IN THE WEEK AS A MEDIUM-PERIOD NORTHWEST SWELL FURTHER INCREASES.
SURF ALONG EAST FACING SHORES WILL BE ELEVATED AND CHOPPY THROUGH
MONDAY DUE TO THE LOCALLY STRONG TRADES.
A SMALL, LONG-PERIOD WEST SWELL ORIGINATING FROM TYPHOON CHOI-WAN
IS FORECAST TO REACH THE ISLANDS THURSDAY INTO THE WEEKEND, WHICH MAY
PRODUCE MODERATE SURF FOR WEST-FACING SHORES OF THE BIG ISLAND.
FIRE WEATHER
BREEZY TRADES WILL CONTINUE THROUGH MONDAY. 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 6 KFT TO 8 KFT THROUGH MONDAY.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST MONDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...FOSTER
AVIATION...PECHACEK
MARINE...TS
FIRE WEATHER...FOSTER
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