850
FXHW60 PHFO 131358
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
358 AM HST TUE OCT 13 2026
SYNOPSIS
MODERATE TRADES WILL BUILD BACK INTO THE REGION TODAY. A WEAK
TROUGH NEAR THE BIG ISLAND THIS MORNING IS PRODUCING SHOWERS AND
CLOUDS OVER THE EASTERN END OF THE ISLAND CHAIN. AS THIS TROUGH
WEAKENS AND MOVES WESTWARD, EXPECT SHOWERS TO TREND DOWN BY
TONIGHT. ELSEWHERE, DRIER CONDITIONS WILL PREVAIL. TRADE WINDS
ARE ANTICIPATED TO BECOME BREEZY BY THE END OF THE WEEK AS HIGH
PRESSURE STRENGTHENS NORTH OF THE STATE. SLIGHTLY WETTER TRADES
WILL BE POSSIBLE THIS WEEKEND.
DISCUSSION
EARLY THIS MORNING, A SURFACE TROUGH IS LOCATED OVER THE EASTERN
SIDE OF THE BIG ISLAND. SHOWERS AND WIDESPREAD CLOUD COVER
ASSOCIATED WITH THIS TROUGH HAVE BEEN MOVING OVER BIG ISLAND
WINDWARD LOCATIONS THROUGHOUT THE NIGHT, AND WILL CONTINUE
THROUGHOUT THE MORNING. SEVERAL LOCATIONS ACROSS THE BIG ISLAND
HAVE PICKED UP OVER AN INCH OF RAIN SINCE 8PM HST, WITH A COUPLE
OF SPOTS RECEIVING OVER AN INCH IN A HALF IN THE PAST 24 HOURS.
WITH THAT SAID, RADAR ESTIMATED RAINFALL RATES HAVE BEEN STEADILY
IN THE LIGHT TO MODERATE RANGE, PRECLUDING ANY FLOODING CONCERNS
AT THIS TIME. TO A LESSER EXTENT, SOME OF THE MOISTURE ASSOCIATED
WITH THIS WEAK TROUGH HAS SPREAD TO PORTIONS OF MAUI AS WELL.
ELSEWHERE ACROSS THE STATE, DRIER AIR REMAINS IN PLACE WITH FEWER
CLOUDS AND SHOWERS OCCURRING.
TODAY THE TROUGH WILL WEAKEN AS IT MOVES WESTWARD, WHILE A LOW
ALOFT MOVES OFF TO THE EAST. PREVAILING CLOUDS AND SHOWERS
ASSOCIATED WITH THE TROUGH WILL DIMINISH LATER THIS MORNING, BUT
LINGERING MOISTURE NEARBY MAY ENHANCE AFTERNOON CLOUDS AND SHOWER
ACTIVITY OVER THE BIG ISLAND INTERIOR. MODERATE TRADE WINDS WILL
BE BUILDING BACK INTO THE REGION, AND MAY BECOME LOCALLY BREEZY
WITHIN TYPICALLY WINDY AREAS BY THIS AFTERNOON. A FEW PASSING
SHOWERS WILL BE POSSIBLE FOR THE SMALLER ISLANDS TODAY, MAINLY
FAVORING WINDWARD AND MAUKA LOCATIONS.
BY WEDNESDAY, CONDITIONS ARE FORECAST TO BECOME DRIER AS THE
AFOREMENTIONED FEATURES WILL HAVE MOVED WELL AWAY FROM THE
ISLANDS. TRADE WINDS THEN ARE EXPECTED TO INCREASE THURSDAY INTO
THE WEEKEND AS HIGH PRESSURE TO THE NORTH BECOMES ESTABLISHED AND
STRENGTHENS. AS TRADE WINDS INCREASE, PASSING SHOWERS WILL FAVOR
WINDWARD AND MOUNTAIN AREAS, AND COULD INCREASE SLIGHTLY THIS
WEEKEND.
AVIATION
LIGHT TO OCCASIONALLY MODERATE TRADES WILL PERSIST THROUGH THE
DAY. LIGHTER WINDS MAY ALLOW FOR THE DEVELOPMENT OF LOCALIZED
DAYTIME SEA BREEZES WITHIN MORE TRADE WIND-PROTECTED LEEWARD
AREAS. AFTERNOON WARMTH WILL CREATE THICKENING UPSLOPE CLOUDS AND
ISOLATED SHOWERS THAT MAY INTRODUCE BRIEF PERIODS OF MVFR CEILINGS
AND VISIBILITIES. OTHERWISE, VFR CONDITIONS WILL PREVAIL.
AIRMET SIERRA IS IN EFFECT FOR MOUNTAIN OBSCURATION ALONG BIG
ISLAND'S EAST AND SOUTHEAST-FACING SLOPES UNTIL FURTHER NOTICE.
MARINE
GENTLE TO MODERATE TRADE WINDS WILL PERSIST THROUGH WEDNESDAY AS
AS A SURFACE RIDGE REMAINS ANCHORED FAR NORTHEAST OF THE STATE AND
A WEAK TROUGH DISSIPATES NEAR THE BIG ISLAND. TRADES WILL
STRENGTHEN TO MODERATE TO LOCALLY FRESH THURSDAY AS SURFACE HIGH
PRESSURE BUILDS FAR NORTH OF THE STATE. TRADES WILL FURTHER
STRENGTHEN TO FRESH TO LOCALLY STRONG LATE FRIDAY THROUGH THE
WEEKEND AND A SMALL CRAFT ADVISORY (SCA) WILL LIKELY BE NEEDED
FOR THE TYPICALLY WINDY WATERS AROUND BIG ISLAND AND MAUI.
A FRESH, LONG PERIOD NORTHWEST SWELL WILL BUILD TODAY, PUSHING
SURF ALONG NORTH AND WEST FACING SHORES TO NEAR SEASONAL AVERAGES
THROUGH WEDNESDAY. THIS SWELL WILL DECLINE THURSDAY AND FRIDAY. BY
LATE FRIDAY, A MEDIUM PERIOD NORTH- NORTHWEST SWELL WILL BUILD
AND ONCE AGAIN HELP BRING SURF TO NEAR SEASONAL AVERAGES THROUGH
THE WEEKEND.
SOUTH SHORE SURF WILL REMAIN ELEVATED THROUGH WEDNESDAY AS A LONG
PERIOD SOUTH- SOUTHWEST SWELL SLOWLY DECLINES. ANOTHER LONG
PERIOD SOUTH SWELL WILL HELP PRODUCE SURF NEAR SEASONAL AVERAGE
THURSDAY INTO EARLY THIS WEEKEND.
SURF ALONG EAST FACING SHORES WILL REMAIN SMALL THROUGH THURSDAY
AS SMALL WIND WAVES AND TINY EAST SWELL PERSIST. CHOPPY SURF WILL
INCREASE SLIGHTLY AS TRADE WINDS STRENGTHEN ACROSS THE REGION
FRIDAY INTO THE WEEKEND.
FIRE WEATHER
MODERATE TRADE WINDS WILL CONTINUE THROUGH THE FIRST HALF OF THE
WEEK. DRY AIR WILL KEEP RH LEVELS NEAR-CRITICAL VALUES EACH
AFTERNOON FOR PARTS OF THE STATE FOR THE NEXT SEVERAL DAYS, BUT
WINDS WILL BE A LIMITING FACTOR. INVERSION HEIGHTS WILL RANGE FROM
NEAR 5,000 FEET OVER THE WESTERN END OF THE STATE TO AROUND
12,000 FEET OVER THE EASTERN END. WINDS WILL INCREASE DURING THE
SECOND HALF OF THE WEEK, BUT MOISTURE LEVELS ARE ALSO EXPECTED TO
INCREASE A BIT.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...VAUGHAN
AVIATION...BLOOD
MARINE...THOMAS
FIRE WEATHER...VAUGHAN
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