409
FXHW60 PHFO 121303
AFDHFO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE HONOLULU HI
303 AM 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. A WEAK DISTURBANCE
WILL LIFT OUT OF THE DEEP TROPICS TOWARDS THE MIDDLE OF NEXT WEEK
BRINGING A SLIGHT UPTICK IN TRADES, INCREASED HUMIDITY, AND A
BETTER CHANCE FOR SHOWERS.
DISCUSSION
MORNING SATELLITE WATER VAPOR IMAGERY SHOWS A LARGE UPPER LEVEL
LOW WELL NORTHEAST OF THE STATE AND GENERALLY DRY NORTHWEST FLOW
ALOFT AS A WEAK SHORT WAVE MOVES SOUTHEAST OVER THE AREA. REMNANT
MOISTURE AND SHOWERS REMAIN WEST AND SOUTHWEST OF THE BIG ISLAND
AND WILL GRADUALLY DISSIPATE THROUGH THE MORNING.
DRIER AIR IN PREVAILING TRADE WINDS WILL CONTINUE THROUGH THE
WEEKEND. TYPICAL TRADES WEATHER IS EXPECTED OVER THE NEXT FEW
DAYS WITH OCCASIONAL LIGHT SHOWERS ACROSS THE WINDWARD SIDE OF THE
ISLANDS EACH DAY.
A TROPICAL DISTURBANCE CURRENTLY SEVERAL HUNDRED MILES SOUTHEAST
OF HILO WILL MOVE NORTHWESTWARD OVER THE NEXT SEVERAL DAYS. NHC
FORECAST HAS DROPPED TO A 10% CHANCE OF DEVELOPMENT INTO A
TROPICAL CYCLONE OVER THE NEXT 7 DAYS. MOST LIKELY SCENARIO IS FOR
THIS FEATURE TO HELP PULL TROPICAL MOISTURE INTO THE AREA, THOUGH
HOW MUCH AND WHEN WILL DEPEND ON ITS TRACK. FOR NOW EXPECT
PRECIPITABLE WATER AND DEW POINTS TO INCREASE ONCE AGAIN WITH A
SMALL INCREASE IN TRADE WINDS AND HIGHER PRECIPITATION CHANCES
TOWARDS THE MIDDLE OF NEXT WEEK.
TROPICAL STORM NORBERT IS CURRENTLY AROUND 1820 MILES ESE OF
HILO, MOVING WEST-NORTHWEST AT 9 MPH. THIS SYSTEM IS NOW FORECAST
TO REMAIN AT TROPICAL STORM STRENGTH THROUGH WEDNESDAY, WHEN IT
WILL STILL BE SOUTHEAST OF HAWAII. THERE REMAINS HIGHER THAN
NORMAL UNCERTAINTY ON WHERE THIS STORM WILL TRACK AS IT
APPROACHES, SO CONFIDENCE IN IMPACTS - IF ANY - TO THE ISLANDS
REMAINS LOW.
AVIATION
A LARGE AREA OF LOW PRESSURE CENTERED APPROXIMATELY 1,200 MILES
NORTHEAST OF THE ISLANDS IS DISRUPTING THE DOWNSTREAM PRESSURE
GRADIENT BACK TO THE ISLANDS. THIS HAS RESULTED IN WEAKER REGIONAL
TRADE WINDS THAT WILL PERSIST THROUGH THE WEEKEND. WINDS MAY
BECOME LIGHT ENOUGH WITHIN MORE WIND-PROTECTED LEEWARD AREAS TO
INITIATE LOCAL BREEZES. RELATIVELY DRIER NORTHERLY AIR IS WORKING
ITS WAY IN ACROSS THE STATE AND WILL LIMIT SHOWER ACTIVITY.
AIRMET SIERRA REMAINS IN EFFECT FOR MOUNTAIN OBSCURATION FOR BIG
ISLAND'S NORTH AND EAST-FACING SLOPES THROUGH 6 AM HST WITH
IMPROVING CONDITIONS THEREAFTER.
MARINE
MODERATE TO LOCALLY FRESH TRADES WILL CONTINUE THROUGH THE
FORECAST PERIOD. A TROPICAL DISTURBANCE MOVING IN FROM THE TRADE
WINDS MAY BRING AN INCREASE OF SHOWERS TO THE COASTAL WATERS BY
TUESDAY INTO WEDNESDAY.
SURF ALONG SOUTH FACING SHORES WILL GRADUALLY DECLINE THROUGH THE
WEEKEND AS THE SMALL MEDIUM TO LONG PERIOD ENERGY SLOWLY FADES.
A LOW IN THE SOUTH PACIFIC NEAR AUSTRALIA AND NEW ZEALAND WILL
BRING THE POTENTIAL FOR A MODERATE LONG PERIOD SWELL FOR HAWAII
LATE NEXT WEEK.
EAST FACING SHORES WILL ALSO REMAIN AT SMALL TO MODERATE THROUGH
THE FORECAST PERIOD DUE TO THE FRESH TO LOCALLY STRONG TRADE
WINDS. 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...BLOOD
MARINE...WALSH
FIRE WEATHER...SS
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