857
FXHW60 PHFO 051339
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
339 AM HST MON OCT 5 2026
SYNOPSIS
DRY, STABLE, BREEZY TRADES WILL CONTINUE THROUGH TODAY, BRINGING
LIMITED SHOWERS MAINLY ALONG WINDWARD AND MAUKA AREAS. WINDS WILL
BEGIN TO EASE LATER TODAY THROUGH TUESDAY. A DEVELOPING AREA OF
LOW PRESSURE NORTH OF THE STATE WILL FURTHER WEAKEN WINDS AND TURN
THEM OUT OF THE SOUTH WEDNESDAY. CHANCES OF SHOWERS WILL INCREASE
DURING THE SECOND HALF OF THE WEEK AS WELL AS THE POTENTIAL FOR
HEAVY RAIN ACROSS HAWAII.
DISCUSSION
LATEST SURFACE ANALYSIS SHOWS HIGH PRESSURE NORTH OF THE STATE
AND A WEAK DISTURBANCE PASSING TO THE SOUTH, RESULTING IN BREEZY
TRADE WINDS. RADAR AND SATELLITE IMAGERY SHOW SCATTERED LOW CLOUDS
WITH EMBEDDED LIGHT SHOWERS. OVERNIGHT RAINFALL TOTALS RANGE FROM
.20 TO .30 INCHES OF RAINFALL MOSTLY FOR WINDWARD AND MAUKA AREAS
OF MAUI COUNTY AND THE BIG ISLAND. MODEST AMOUNTS WERE OBSERVED
OVER THE THE REST OF THE STATE AS SHOWER COVERAGE BECOMES MORE
ISOLATED. CHANCES OF SHOWERS WILL TREND DOWN THROUGH THE DAY
TODAY. WINDS WILL GRADUALLY EASE LATER TODAY AND TONIGHT AS THE
HIGH NORTH OF THE STATE WEAKENS AND SHIFTS NORTHEAST. SHOWERS WILL
REMAIN LIMITED ALONG WINDWARD AND MAUKA AREAS.
A HYBRID LAND/SEABREEZE AND LIGHT TRADE WIND PATTERN WILL DEVELOP
TUESDAY AS WINDS CONTINUE TO EASE. WINDS WILL THEN 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 SOUTHERLY WINDS WILL DRAW DEEP TROPICAL
MOISTURE OVER THE ISLANDS, WHILE A COLD POOL ALOFT ASSOCIATED WITH
THE UPPER LOW WILL ACT TO DESTABILIZE THE ATMOSPHERE OVER THE
STATE. 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 WITH INCREASING INSTABILITY, HEAVY
RAIN WILL BECOME LIKELY. THE TIMING AND LOCATION OF THE MOISTURE
CONTINUES TO BE DEPICTED SLIGHTLY DIFFERENT IN THE LONG RANGE
MODELS, BUT AT THIS TIME IT APPEARS ALL THE ISLANDS WILL BE
IMPACTED AT SOME POINT. THUS, NOT GETTING TOO SPECIFIC IN THE
FORECAST DETAILS FOR NOW, BUT EXPECT AN OVERALL WETTER PATTERN AND
SOUTHERLY WINDS FROM AROUND LATE WEDNESDAY THROUGH AT LEAST
FRIDAY, AND POSSIBLY LINGERING INTO THE UPCOMING WEEKEND.
AVIATION
MODERATE TO BREEZY TRADE WINDS WILL CONTINUE ACROSS THE REGION
TODAY WITH ISOLATED SHOWERS FAVORING WINDWARD AND MOUNTAIN AREAS
WHERE SHORT-LIVED MVFR CONDITIONS ARE POSSIBLE. OTHERWISE, VFR
CONDITIONS WILL PREVAIL ACROSS THE STATE.
AIRMET SIERRA REMAINS IN EFFECT FOR MOUNTAIN OBSCURATION ACROSS
MUCH OF THE BIG ISLAND EARLY THIS MORNING. IMPROVING CONDITIONS
ARE EXPECTED LATER TODAY.
AIRMET TANGO ALSO REMAINS IN EFFECT FOR MODERATE TURBULENCE
DOWNWIND OF MOUNTAIN TERRAIN DUE TO THE BREEZY TRADES.
MARINE
HIGH PRESSURE NORTH OF THE HAWAIIAN ISLANDS WILL MAINTAIN FRESH TO
LOCALLY STRONG TRADE WINDS TODAY. THE SMALL CRAFT ADVISORY FOR
THE WINDIER WATERS AND CHANNELS AROUND MAUI COUNTY AND THE BIG
ISLAND REMAINS IN EFFECT THROUGH THIS AFTERNOON. THEREAFTER, HIGH
PRESSURE TO THE NORTH WEAKENS AND TRADES WILL START TO DIMINISH.
TROUGHING DEVELOPING NORTHWEST OF THE ISLANDS WILL LIKELY CAUSE
WINDS TO VEER OUT OF THE SOUTHEAST AROUND MIDWEEK AND BRING
INCREASED SHOWER ACTIVITY FOR THE LATTER HALF OF THE WEEK.
A NEW SMALL, LONG-PERIOD SOUTH SWELL WILL SLOWLY FILL IN TODAY AND
TONIGHT, CAUSING SURF ALONG SOUTH AND WEST FACING SHORES TO INCREASE
TO SLIGHTLY ABOVE SEASONAL AVERAGES TUESDAY INTO WEDNESDAY. SURF IS
THEN FORECAST TO DROP TO NEAR OR SLIGHTLY BELOW AVERAGE FOR THE REST
OF THE WEEK, MAINTAINED BY A MIX OF NEW, SMALL SOUTH SWELLS.
A SMALL, MEDIUM-PERIOD NORTHWEST SWELL BUILDS THIS MORNING AND PEAKS
LATE TODAY, PRODUCING A SMALL BUMP IN SURF ALONG NORTH-FACING SHORES
THAT BEGINS FADING ON TUESDAY. HOWEVER, A LARGER, LONG-PERIOD
NORTHWEST SWELL WILL ARRIVE ON TUESDAY THAT WILL PUSH SURF HIGHER INTO
WEDNESDAY. SURF IS THEN LIKELY TO HOLD THROUGH THE END OF THE WEEK
EVEN AS SWELL ENERGY BECOMES SHORTER PERIOD AS IT IS REINFORCED BY A
LOW TO THE NORTH-NORTHWEST OF THE HAWAIIAN ISLANDS. SURF ALONG EAST
FACING SHORES WILL FALL BELOW SEASONAL AVERAGES AS LOCALLY STRONG
TRADES DIMINISH TONIGHT.
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 GRADUALLY EASE LATER TODAY INTO TUESDAY WITH
RH VALUES 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 7 KFT TO 8 KFT THROUGH TUESDAY.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST THIS EVENING FOR ALENUIHAHA
CHANNEL-BIG ISLAND LEEWARD WATERS-BIG ISLAND SOUTHEAST WATERS-
MAALAEA BAY-PAILOLO CHANNEL.
DISCUSSION...ALMANZA
AVIATION...VAUGHAN
MARINE...QUESADA
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