181
FXHW60 PHFO 130134
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
334 PM HST SAT SEP 12 2026
SYNOPSIS
DRIER TRADE WINDS WILL PREVAIL INTO EARLY NEXT WEEK WITH LIGHT
SHOWERS ON THE WINDWARD SIDE OF THE ISLANDS. LOW LEVEL
CONVERGENCE ALONG A SURFACE TROUGH WILL BRING A MODEST INCREASE
IN CLOUDS AND SHOWERS LATE MONDAY INTO TUESDAY. MORE RAIN IS
EXPECTED THROUGH THE SECOND HALF OF THE WEEK AS REMNANTS OF
TROPICAL STORM NORBERT PASS BY.
DISCUSSION
HIGH PRESSURE FAR TO THE NORTH IS DRIVING GENTLE TRADE WINDS
ACROSS HAWAII TODAY, WEAKENED BY SURFACE TROUGHS TO THE NORTHEAST
AND EAST OF THE AREA. VISIBLE SATELLITE THIS AFTERNOON SHOWS
PARTLY TO MOSTLY CLOUDY SKIES ACROSS THE ISLANDS MAINLY DUE TO THE
LOCALIZED SEA BREEZES. RADAR SHOWS VERY LITTLE RAINFALL ACROSS THE
AREA THIS AFTERNOON. LIGHT TRADE WINDS AND ISOLATED SHOWERS WILL
CONTINUE THROUGH THE REST OF THE WEEKEND.
THE TROUGH MENTIONED TO THE EAST IS FORECAST TO TRACK WESTWARD
OVER THE NEXT SEVERAL DAYS. LOW LEVEL CONVERGENCE ALONG THIS
FEATURE WILL BRING A MODEST INCREASE IN CLOUDS AND SHOWERS LATE
MONDAY INTO TUESDAY, INITIALLY REACHING THE BIG ISLAND WITH
SHOWERS BECOMING MORE DIFFUSE AS THE TROUGH MOVES WEST.
TROPICAL STORM NORBERT IS CURRENTLY AROUND 1675 MILES EAST OF
HILO, MOVING WEST-NORTHWEST AT 12 MPH. RECENT ADVISORY UPDATES
FROM THE NATIONAL HURRICANE CENTER SHOW THIS SYSTEM BECOMING
POST-TROPICAL ON TUESDAY WHILE TURNING SLIGHTLY WEST SOUTHWEST AS
THE MOTION BECOME DICTATED BY THE LOW LEVEL TRADE WINDS. TRADE
WINDS WILL STRENGTHEN STATEWIDE AS THE GRADIENT TIGHTENS AROUND
WHAT IS LEFT OVER OF NORBERT, LIKELY A TROUGH BY THURSDAY AND
FRIDAY. RAINFALL WILL ALSO INCREASE EAST TO WEST ACROSS THE STATE
FROM WEDNESDAY NIGHT THROUGH FRIDAY NIGHT. A SURFACE AND UPPER TROUGH
OVER THE AREA, WITH PRECIPITABLE WATER VALUES OVER 2 INCHES WILL
LIKELY BE ENOUGH TO PRODUCE SOME FLOODING ACROSS THE STATE.
STRENGTHENING TRADE WINDS WILL KEEP SHOWERS MOVING ALONG AND
FOCUSED WINDWARD, BUT LEEWARD SIDES WILL ALSO SEE A FAIR SHARE OF
RAIN. STILL A BIT FAR OUT IN THE FORECAST TO GET TOO DETAILED FOR
NOW, BUT A DEFINITELY A TIME PERIOD TO FOCUS ON.
AVIATION
A LARGE UPPER LEVEL LOW WELL NORTHEAST OF THE ISLANDS IS
WEAKENING THE PRESSURE GRADIENT AND THEREFORE THE TRADE WINDS NEAR
HAWAII. THESE WEAK TO MODERATE TRADES WILL CONTINUE THROUGH SUNDAY.
WINDS MAY BECOME LIGHT ENOUGH WITHIN MORE WIND-PROTECTED LEEWARD
AREAS TO INITIATE LOCAL TOPOGRAPHICALLY-DRIVEN BREEZES.
THESE TRADES ARE ALSO RELATIVELY DRY, AND WILL LIMIT SHOWER
ACTIVITY.
MARINE
MODERATE TO LOCALLY FRESH TRADES WILL CONTINUE THROUGH EARLY NEXT
WEEK BEFORE GRADUALLY STRENGTHENING THROUGH THE LATTER HALF OF THE
WEEK. MOISTURE ASSOCIATED WITH A WEAK TROUGH MOVING IN ON THE
TRADE WIND FLOW MAY BRING A SLIGHT UPTICK IN SHOWER ACTIVITY TO
THE COASTAL WATERS TUESDAY INTO WEDNESDAY. WHILE THE CURRENT
FORECAST HAS TROPICAL STORM NORBERT DISSIPATING BEFORE IT NEARS
THE HAWAIIAN COASTAL WATERS FROM THE EAST, REMNANT MOISTURE FROM
THIS SYSTEM IS EXPECTED TO ARRIVE LATE NEXT WEEK, LIKELY BRINGING
MORE SHOWERS.
SURF ALONG SOUTH-FACING SHORES WILL GRADUALLY DECLINE THROUGH THE
WEEKEND AS THE SMALL, MEDIUM- TO LONG-PERIOD ENERGY SLOWLY FADES.
A MODERATE, LONG-PERIOD SWELL GENERATED BY A LOW THAT PASSED NEAR
AUSTRALIA AND NEW ZEALAND IS FORECAST TO ARRIVE MID TO LATE WEEK
NEXT WEEK AND BRING A BUMP TO SOUTH SHORE SURF.
SURF ALONG EAST-FACING SHORES WILL REMAIN SMALL TO MODERATE THROUGH
EARLY NEXT WEEK, THEN BUILD SLIGHTLY OVER THE LATTER HALF OF THE
WEEK AS THE TRADE WINDS STRENGTHEN AND SOME EASTERLY SWELL FROM
NORBERT POTENTIALLY MOVES IN. FLAT TO TINY SURF ALONG NORTH
FACING SHORES IS EXPECTED THROUGH THE FORECAST PERIOD.
FIRE WEATHER
FIRE WEATHER RISK WILL REMAIN LOW THE NEXT SEVERAL DAYS DUE LIGHT
TO MODERATE WINDS AND THE EFFECTS OF RECENT RAINFALL. INVERSION
HEIGHTS ARE EXPECTED TO REMAIN ELEVATED OR WEAK THROUGH MONDAY.
HFO WATCHES/WARNINGS/ADVISORIES
NONE.
DISCUSSION...FOSTER
AVIATION...PARKER
MARINE...FARRIS
FIRE WEATHER...FOSTER
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