262
FXHW60 PHFO 151323
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
323 AM HST Tue Sep 15 2026

.SYNOPSIS...

Light to moderate trades will strengthen through Wednesday. Moisture
from the remains of Norbert should move through the islands
Wednesday night through Friday morning as trades strengthen to
moderate to fresh levels. Drier air will move back in this weekend
as trades continue. Moisture from the remnants of tropical
depression 15-E may bring another round of enhanced showers early
next week.

&&

.DISCUSSION...
Radar and satellite show showers mainly offshore to the north of
Maui County and Oahu this morning. Only isolated showers were
noted over land, mainly Molokai. Winds averaged 5 to 15 mph.

A large surface high pressure system centered almost 2000 miles
northeast of the state dominated the Pacific between Hawaii and
Alaska this morning. This high will weaken and slide slowly
southeast through the week, as a trough moves east across the
northern Pacific. Trades will continue to bring ENE to E winds to
the region. Embedded in this flow is an area of moisture from the
remnants of Norbert, and this moisture will bring a sharp increase
in showers from late Wednesday night through early Friday.
Instability will be sufficient for an isolated thunderstorm as
well. Heavy rain is possible, and a flood watch may be needed as
we get closer in time.

Moisture will decrease late Friday through the weekend, but the
latest guidance shows that another area of increasing moisture
(from the remnants of tropical depression 15-E) will likely move
into the area Monday or Tuesday next week. The GFS is especially
bullish with this moisture, showing PW values over 2 inches. The
ECMWF is not as wet. A better estimate of how much moisture this
system will bring should be available by Friday, just as the
initial moisture from the remnants of Norbert depart. Trade winds
are forecast to be moderate to breezy starting Wednesday and
lasting into early next week.

&&

.AVIATION...
Moderate trade winds will continue through the morning, then
gradually strengthen to become locally breezy this afternoon into
the evening. Moisture along a dissipating surface trough moving
over the eastern half of the state this morning will move up the
island chain through the day and increase windward cloud and
shower coverage as it passes through. MVFR conditions will be
possible in passing showers. Otherwise, VFR conditions will
prevail.

AIRMET Sierra is in effect for tempo mountain obscuration for
windward areas of the Big Island through Oahu and may be needed
through the morning hours as showers linger.

&&

.MARINE...
Moderate to locally fresh trade winds will persist today as a
weak trough lingers to the northeast. By Wednesday, high pressure
building north of the islands will increase the trade winds into
the fresh to locally strong range through the weekend. Also by
Wednesday afternoon, the remnants of Norbert will begin to move
into the offshore waters as a trough and increase shower coverage
as it traverses east to west across the islands, potentially
through the weekend.

A series of long-period south to southwest swells will fill in through
the week, leading to a gradual increase in surf for south-facing
shores through the week. The first pulse fills in today into Wednesday
out of the southwest, followed by larger south-southwest swells
Friday into the weekend. Small surf is expected through Wednesday,
after which an upward trend is expected, and surf could approach
advisory thresholds by this weekend.

Surf along east-facing shores should see a gradual increase this week
as trade winds strengthen and a small, medium-period east swell from
Tropical Storm Norbert arrives. Flat to tiny surf along north facing
shores is expected through the forecast period.

&&

.FIRE WEATHER...
Fire weather risk should remain low through the remainder of the
week due to light to moderate winds and the effects of recent (and
upcoming) rainfall. Inversion heights from Maui to the Big Island
should be 7000 to 8000 ft through Wednesday. Showers will
dramatically increase from late Wednesday into early Friday,
keeping vegetation moist.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Parker
AVIATION...Farris
MARINE...Quesada