885
FXHW60 PHFO 210636
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
836 PM HST Thu Jun 20 2024

.SYNOPSIS...
High pressure far north of the islands will maintain breezy and
gusty trade winds through early next week. Passing showers will
favor will favor windward slopes, especially during nights and
mornings, with some light rainfall occasionally spreading
leeward.

&&

.DISCUSSION...
A stable, breezy, and gusty trade wind flow remains in place,
driven by strong high pressure sitting 700 to 800 miles north of
the state, and a robust mid-level ridge over the region is
maintaining stable conditions with an inversion based at 6,000 to
7,000 feet. A narrow band of low-level moisture is fueling modest
showers over windward areas this evening, while scattered showers
are lingering on the South Kona slopes. Expect a decrease in
rainfall later tonight as a narrow slot of dry air moves overhead.

A modest and brief uptick in winds is due on Friday as the high to
the north builds slightly. This will lead to borderline Wind
Advisory conditions the typically windy areas, such as the Maui
Central Valley, portions of west Maui, the leeward areas of the
Kohala Districts, the Humuula Saddle, Kau, and parts of the Hawaii
Volcanoes National Park. After drier conditions in the morning,
another band of moisture will spread over the state, leading to an
increase in mainly windward rainfall.

Breezy trade winds and a typical summertime rainfall pattern will
prevail this weekend into early next week. Modest showers will be
focused over windward areas, mainly at night and in the morning.
With the exception of afternoon and evening showers over the Kona
slopes of the Big Island, leeward areas will be mostly dry. Trades
look to decline to moderate levels Tuesday or Wednesday as the
high to the north is weakened and displaced eastward.

&&

.AVIATION...
Breezy to locally windy trade winds will continue across the
Hawaii region for the next few days. Brief passing showers are
expected mainly over windward and mountain areas, favoring the
overnight to early morning hours.

AIRMET Sierra for mountain obscuration remains in effect for
windward mountain slopes of Kauai, Oahu, Molokai, Maui, and Big
Island.

AIRMET Tango remains in effect for moderate low level turbulence
over and downwind of island mountains due to the breezy trade
winds.

&&

.MARINE...
Strong easterly trades will continue into early next week,
supporting the Small Craft Advisory in place for all waters. Seas
have responded and will remain rough, with heights hovering
around and just under the advisory level over exposed waters.
Guidance shows a slight downward trend next week between Tuesday
and midweek due to the surface ridge potentially weakening to the
north.

Surf along east-facing shores will remain rough through early
next week due to the aforementioned strong trades locally and
upstream of the state.

Surf along south-facing shores will trend up to around average
this weekend as a small south swell arrives. This should be short-
lived, with a downward trend expected early next week. Despite a
blocking high that has set up over our typical swell window
near/southeast of New Zealand, guidance shows a gale forming to
its northeast with the head of the fetch aimed at the islands
around 2,500-2,700 nautical miles away within the 170 to
190-degree directional band. Given the shorter travel distance,
surf could trend up late next week if this system materializes
this weekend.

Surf along north-facing shores could trend up above flat levels
early next week due to a small, medium-period northwest swell from
a marginal gale lifting northeastward toward the Aleutians
tonight/Friday. On its heels is a compact storm-force low
developing near Japan that could send a similar northwest swell
through the area late next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Saturday for all Hawaiian
waters.

&&

$$

DISCUSSION...Wroe
AVIATION...Bohlin
MARINE...Gibbs