696
FXHW60 PHFO 130631
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
831 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
EVENING SATELLITE IMAGERY SHOWS PARTLY TO MOSTLY CLOUDY SKIES
CONTINUING ACROSS THE ISLANDS WITH JUST A FEW LIGHT SHOWERS NEAR
THE SOUTHERN TIP OF THE BIG ISLAND. LIGHT TRADE WINDS AND
ISOLATED SHOWERS WILL CONTINUE THROUGH THE REST OF THE WEEKEND.
A BROAD UPPER LEVEL LOW CURRENTLY NORTHEAST OF THE ISLANDS IS
FORECAST TO TRACK WESTWARD OVER THE NEXT SEVERAL DAYS. MOISTURE
ASSOCIATED WITH A DISTURBANCE CURRENTLY NEAR 13N 148.5W MAY BE
PULLED NORTHWARD INTO THE EASTERN HALF OF THE STATE AS BOTH IT AND
THE TROUGH MOVE WESTWARD. LOW LEVEL CONVERGENCE 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 1615 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...SS
AVIATION...PHILLIPS
MARINE...SHIGESATO
FIRE WEATHER...SS
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