Area Forecast Discussion for Hawaii

Area Forecast Discussion   Issued: 05/10/2026 11:49:00 AM UTC

                        
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FXHW60 PHFO 100149 CCA
AFDHFO

Area Forecast Discussion...CORRECTED
National Weather Service Honolulu HI
349 PM HST Sat May 9 2026

.SYNOPSIS...
Upper ridging will become established over the coming week.
There is a weak surface trough that will move west and exit the
state through Monday. This will bring increased showers to western
islands through Sunday. An upper level low may develop mid-week
to our northeast, but it is unclear what, if any, impact it will
have on our weather. The main story for the next week is trade
winds, increasing in speed tonight into Sunday, bringing mainly
windward and mauka showers.

&&

.DISCUSSION...
Showers were numerous this afternoon across the Kona region on Big
Island and across Oahu, and isolated to scattered on other
islands. Between low clouds associated with the showers, and high
clouds streaming northeast, skies were mostly cloudy early this
afternoon. Trade winds were building in across the region, with
northeast winds averaging 10 to 20 mph with gusts 20 to 30 mph in
most areas.

Over the next few days, a weak broad trough aloft to our north
will be replaced with a ridge. This change aloft will help create
a stronger surface ridge to the north, and this will strengthen
our developing trade winds. A weak surface trough, associated with
an increase in moisture, was moving west through the central
islands this afternoon. It is expected to continue slowly moving
west as it weakens further, exiting the state by Monday. As it
does, expect areas of showers to continue to develop and be
carried west or WSW on the developing trade winds.

These trades will strengthen through Sunday, and remain moderate
to breezy through most of the coming week. Upper ridging to our
north will be the dominant feature of the coming week. However, models
are coming into better agreement that an upper low may interrupt
the ridge beginning around the middle of next week. There is
little agreement on how strong this low might be or exactly where
it will be positioned. The general consensus at this time is for
it to form sometime between Wednesday and Friday, most likely to
our northeast. It could end up being a factor in our weather
(increased chance of rain and/or weakening trades), but it is too
early to be sure. Otherwise, expect a typical trade wind pattern
beginning Monday, with showers mainly windward and mauka.

&&

.AVIATION...
Moderate trades this afternoon will weaken some tonight, then
steadily increase throughout the day Sunday becoming locally
breezy by the afternoon. A weak trough currently passing through
the state will increase showers, especially over windward and
mountain areas with periods of MVFR conditions expected throughout
the rest of the afternoon. A drier airmass will move in from the
east this evening, which should bring a decrease of showers
tonight from east to west. One exception is over Kauai, where
showery conditions are expected to persist through tonight. Sunday
should be a much drier day with some lingering moisture near
Kauai.

AIRMET Sierra remains in effect for mountain obscuration over
Kauai, Oahu, Molokai and Maui due to the passing showers. AIRMET
Sierra should get cancelled from east to west tonight as the drier
air moves in.

AIRMET TANGO is also in effect for moderate upper level turbulence
for Kauai and Oahu due to a strong jet over the state. Upper level
turbulence will generally decrease on Sunday, but some light
turbulence is still expected throughout the day.

Also, there will likely be a need for AIRMET Tango for low-level
turbulence as trades gradually strengthen Sunday afternoon into
the evening.

&&

.MARINE...
A ridge will remain in place north of the islands with fresh
trade winds tonight, strengthening Sunday and Sunday night and
maintaining next week. A Small Craft Advisory (SCA) is posted for
waters around Kauai and windward Oahu, and waters around Maui
County and Big Island through tonight.

A small northwest swell will maintain through the rest of the
weekend, shifting out of the north to north northwest next week.
Small south swell will fade this weekend with a small, long period
reinforcement Monday through Thursday. Surf along east facing
shores will remain below normal this weekend, but will gradually
increase next week as trade winds strengthen.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Sunday for Kauai Channel-
Kauai Leeward Waters-Kauai Northwest Waters-Kauai Windward
Waters-Oahu Windward Waters.

Small Craft Advisory until 6 AM HST Monday for Alenuihaha
Channel-Big Island Leeward Waters-Big Island Southeast Waters-
Maalaea Bay-Pailolo Channel.


&&

$$

DISCUSSION...Parker
AVIATION...Kino
MARINE...Foster