206
FXHW60 PHFO 131356
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
356 AM HST SAT SEP 13 2025
SYNOPSIS
A BROAD SUBTROPICAL RIDGE WILL LINGER ACROSS THE CENTRAL PACIFIC
BASIN INTO THE MIDDLE OF NEXT WEEK, PRODUCING MODERATE TO LOCALLY
BREEZY TRADE WINDS EACH DAY. BRIEF PASSING SHOWERS OVER WINDWARD
AND MOUNTAIN AREAS WILL RETURN LATER THIS AFTERNOON AND LAST
THROUGH MONDAY EVENING. ONE WRINKLE IN THE FORECAST WILL DEVELOP
FROM TUESDAY INTO WEDNESDAY AS AN EASTERLY WAVE PASSES THROUGH
THE HAWAIIAN ISLANDS INCREASING CLOUDS AND SHOWER TRENDS.
DISCUSSION
THIS MORNINGS SATELLITE IMAGERY SHOWS FAIRLY STABLE STRATOCUMULUS
CLOUDS DRIFTING INTO THE ISLANDS ON THE EASTERLY TRADE WINDS. THIS
MORNINGS UPPER AIR BALLOON SOUNDINGS FROM HILO AND LIHUE SHOW
SUBSIDENCE INVERSION HEIGHTS AT THE 6,000 AND 7,000 FOOT LEVEL
RESPECTIVELY. AT THESE HEIGHTS CLOUDS WILL DEEPEN ENOUGH FOR ONLY
ISOLATED TO SCATTERED SHOWER COVERAGE FAVORING WINDWARD MOUNTAIN
SLOPES OF ALL ISLANDS EXPOSED TO THE EASTERLY TRADE WINDS. BANDS
OF HIGH LEVEL CIRRUS CLOUDS, MADE OF ICE CRYSTALS, WILL DRIFT OVER
THE ISLANDS THROUGH SUNDAY. THESE HIGH LEVEL CIRRUS CLOUDS WILL
LIKELY ENHANCE SUNRISE AND SUNSET COLORS FOR ALL ISLANDS.
A TYPICAL SUMMER FORECAST WITH LITTLE CHANGES TO OUR DAY TO DAY
MODERATE TO LOCALLY BREEZY EASTERLY TRADE WIND WEATHER REGIME
REMAINS IN THE FORECAST THROUGH MONDAY EVENING. ONLY BRIEF PASSING
SHOWERS ARE POSSIBLE WITH TEMPERATURE INVERSION HEIGHTS IN THE
5,000 TO 7,000 FOOT RANGE, FAVORING WINDWARD AND MOUNTAIN AREAS IN
THE OVERNIGHT TO EARLY MORNING HOURS. DRY TRENDS WILL CONTINUE FOR
LEEWARD AREAS THAT ARE WEST OF ISLAND MOUNTAINS.
THE LATEST MEDIUM RANGE MODELS CONTINUE TO SHOW ANOTHER WRINKLE
IN THE FORCE DEVELOPING BY EARLY TUESDAY MORNING, AS A WAVE IN
THE EASTERLIES DRIFTS FROM EAST TO WEST ACROSS THE ISLAND CHAIN.
LOW LEVEL FORCING FROM THIS PASSING LOW LEVEL TROUGH WILL PUSH
SUBSIDENCE INVERSION HEIGHTS INTO THE 8,000 TO 9,000 FOOT RANGE,
DEEPENING MOISTURE LEVELS, AND INCREASING CLOUD AND SHOWER TRENDS
FROM EARLY TUESDAY MORNING NEAR THE BIG ISLAND AND MAUI, THEN
SPREADING WESTWARD TO THE ISLANDS OF OAHU AND KAUAI BY TUESDAY
NIGHT INTO WEDNESDAY MORNING. ONE CHALLENGE WITH THIS FORECAST
WILL BE IN HOW FAR NORTH THE TROUGH TRACKS THROUGH THE ISLANDS. IF
THE TROUGH PASSES FARTHER SOUTH OF THE STATE, THEN THESE SHOWER
TRENDS WILL BE MORE LIMITED FOR THE WESTERN HALF OF THE STATE. WE
HAVE HIGHER CONFIDENCE THAT THE EASTERN HAWAIIAN ISLANDS WILL SEE
ENHANCED SHOWER ACTIVITY, ESPECIALLY IN THE EARLY TUESDAY MORNING
HOURS.
LONG RANGE MODEL SOLUTIONS CONTINUE TO HINT AT ADDITIONAL
ENHANCED SHOWER TRENDS BY THE END OF NEXT WEEK. STAY TUNED.
AVIATION
MODERATE TO LOCALLY BREEZY TRADE WINDS WILL HOLD FOR THE NEXT FEW
DAYS AS HIGH PRESSURE TO THE NORTHEAST REMAINS IN PLACE. BRIEF
PASSING SHOWERS WILL FAVOR WINDWARD AND MOUNTAIN AREAS IN THE
OVERNIGHT TO EARLY MORNING HOURS. VFR CONDITIONS WILL PREVAIL
OUTSIDE OF SHOWERS.
NO AIRMETS ARE IN EFFECT.
MARINE
WEAK SURFACE HIGH PRESSURE WILL REMAIN ANCHORED NORTH OF THE
ISLANDS THE NEXT SEVERAL DAYS. THIS WILL SUPPORT MODERATE TO
LOCALLY STRONG TRADE WINDS ACROSS THE NEARSHORE WATERS. A SMALL
CRAFT ADVISORY (SCA) REMAINS IN EFFECT FOR THE TYPICALLY WINDY
BAYS AND CHANNELS SURROUNDING MAUI COUNTY AND BIG ISLAND THROUGH
SUNDAY AFTERNOON. WINDS MAY BRIEFLY FALL BELOW SCA CRITERIA SUNDAY
MORNING BUT ARE EXPECTED TO RESTRENGTHEN BY THE AFTERNOON HOURS.
MODERATE TRADES WILL PREVAIL THROUGH THE MIDDLE OF NEXT WEEK
BEFORE ONCE AGAIN PICKING BACK UP TO SCA LEVELS ACROSS THE
TYPICALLY WINDY AREAS THURSDAY AND FRIDAY.
THE RECENT SMALL, MEDIUM PERIOD NORTH SWELL IS CURRENTLY ON THE
DECLINE TODAY BUT SHOULD STILL HAVE ENOUGH ENERGY TO KEEP NORTH-
FACING SHORE SURF UP TO NEAR HEAD HIGH HEIGHTS INTO THIS AFTERNOON.
THIS SWELL WILL SIGNIFICANTLY FALL OFF SUNDAY AND PRODUCE WAIST
HIGH SURF BY LATE SUNDAY AFTERNOON. ANOTHER MEDIUM PERIOD NORTH
SWELL ARRIVAL THURSDAY MAY CAUSE A SLIGHT BUMP IN LATE WEEK SURF
ALONG NORTH-FACING SHORES.
SURF ALONG SOUTH-FACING SHORES WILL REMAIN NEAR OR SLIGHTLY ABOVE
LATE SUMMER NORMS THE NEXT COUPLE OF DAYS. THIS MORNING'S ELEVATED
SOUTH SURF WILL FALL THROUGH THE DAY AS THE SMALL, MEDIUM PERIOD
SOUTH SWELL THAT PEAKED YESTERDAY DROPS OFF THROUGH THIS AFTERNOON.
A SMALL LONG PERIOD REINFORCEMENT ARRIVING TONIGHT WILL HOLD
SOUTH SHORE SURF TO AROUND WAIST HIGH SUNDAY.
TYPICAL SHORT PERIOD WIND WAVE CHOP WILL OCCUR ALONG EAST-FACING
SHORES UNDER MODERATE TRADES THIS WEEKEND.
FIRE WEATHER
HUMIDITY LEVELS WILL REMAIN DRY INTO NEXT WEEK WITH INCREASING
HUMIDITY AND SHOWER TRENDS FROM TUESDAY INTO WEDNESDAY AS A WEAK
LOW LEVEL TROUGH DRIFTS FROM EAST TO WEST ACROSS THE ISLAND CHAIN.
WIND SPEEDS WILL LIKELY REMAIN BELOW CRITICAL FIRE WEATHER
THRESHOLDS FOR THE NEXT SEVEN DAYS. TEMPERATURE INVERSION HEIGHTS
NEAR THE BIG ISLAND AND MAUI TODAY WILL RANGE FROM 5,500 TO 6,500
FEET.
HFO WATCHES/WARNINGS/ADVISORIES
SMALL CRAFT ADVISORY UNTIL 6 PM HST SUNDAY FOR MAALAEA BAY-
PAILOLO CHANNEL-ALENUIHAHA CHANNEL-BIG ISLAND LEEWARD WATERS-BIG
ISLAND SOUTHEAST WATERS.
DISCUSSION...BOHLIN
AVIATION...BOHLIN
MARINE...BLOOD
FIRE WEATHER...BOHLIN
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