Area Forecast Discussion for Hawaii

Area Forecast Discussion   Issued: 05/22/2026 12:03:00 AM UTC

                        
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FXHW60 PHFO 211403
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
403 AM HST Thu May 21 2026

.SYNOPSIS...

Trade winds will steadily strengthen today and a wind advisory
remains in effect for areas of Maui County and Big Island through
tonight. Passing showers will continue to move in on breezy to
windy trade winds through next week. As usual, these showers will
be most frequent during the nights and early morning hours across
windward and mauka areas.

&&

.DISCUSSION...
This morning`s radar and satellite imagery shows scattered showers
riding in with the breezy to windy trade winds mainly over
windward and mauka areas. Rainfall totals over the past 24 hours
have varied quite a bit of rainfall amounts of up to 1 to 2 inches
at the wettest areas. 12Z soundings from Lihue and Hilo continues
to show an elevated inversion, which explains the higher rainfall
amounts. As we go through the day today and into tonight, drier
air aloft should really fill in tonight, which should cause the
trade wind inversion to strengthen and lower. This will result in
the winds becoming more gusty later this afternoon into tonight.
Wind gusts in the 50 mph range has been measured at the windier
areas of Maui County and the Big Island, where we have a Wind
Advisory in effect through tonight. The Wind Advisory may have to
be extended through Friday. While we don`t have a Wind Advisory
for Oahu, we could see wind gusts near advisory thresholds later
this afternoon into tonight for select valleys downwind of terrain
such as Manoa Valley.

While the drier air aloft should help lower rainfall amounts
later tonight, strong orographic lifting from the windy trade
winds will continue to produce scattered showers over windward and
mauka areas.

For the weekend, windy conditions will likely continue through
Saturday. Trade winds could drop a notch on Sunday, but
nonetheless breezy to strong trades will likely continue through
early next week. Passing showers will continue to ride in with the
strong trades especially during the night and early morning hours.
Shower coverage could slightly increase towards the first half of
next week as we see a subtle increase of low level moisture.


&&

.AVIATION...

High pressure north of the area will allow fresh to windy trade
winds to prevail today and tomorrow. Stability will increase
through the day as drier air fills in later this morning, leading
to lighter intensity and less frequent showers. However brief
showers could still impact windward and mountain areas, especially
during the evening and early morning hours.

AIRMET Sierra is in effect for mountain obscuration across
windward portions of the Big Island, Kauai, Molokai, and Maui.
This AIRMET will likely be canceled later this morning as
conditions are expected to improve. AIRMET Tango is in place for
low level turbulence over and downwind of terrain. With winds
building and stability increasing, this AIRMET will remain in
place for at least the next couple of days.


&&

.MARINE...

The strong high pressure ridge north of the Hawaiian Islands will
maintain easterly trade winds in the strong to gale range through
Friday morning. A Gale Warning remains in effect for the
Alenuihaha and Pailolo Channels, and Maalaea Bay and a Small
Craft Advisory (SCA) for all remaining island waters. Expect SCA
to continue into the first half of next week.

Small, short to medium period north-northwest (330 degree) swell
energy will decline today. The next small north-northwest (330
degree) swell will move into the Hawaii region on Saturday,
increasing surf heights along north and west-facing shores
through the weekend.

A series of small, long-period south swells will support near-
average surf along south-facing shores over the next several
days. Meanwhile, strengthening trades will maintain elevated surf
along east-facing shores into next week. Surf heights could
approach advisory levels later today along east facing shores.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 AM HST Friday for Big Island North-Big
Island South-Big Island Southeast-Kahoolawe-Kohala-Lanai Leeward-
Lanai Mauka-Lanai South-Lanai Windward-Maui Central Valley North-
Maui Central Valley South-Maui Leeward West-Maui Windward West-
Molokai Leeward South-Molokai North-Molokai Southeast-Molokai
West-Molokai Windward-South Haleakala.

Small Craft Advisory until 6 AM HST Friday for Big Island
Leeward Waters-Big Island Southeast Waters-Big Island Windward
Waters-Kaiwi Channel-Kauai Channel-Kauai Leeward Waters-Kauai
Northwest Waters-Kauai Windward Waters-Maui County Leeward
Waters-Maui County Windward Waters-Oahu Leeward Waters-Oahu
Windward Waters.

Gale Warning until 6 AM HST Friday for Alenuihaha Channel-
Maalaea Bay-Pailolo Channel.


&&

$$

DISCUSSION...Kino
AVIATION...Tsamous
MARINE...Bohlin