960
FXHW60 PHFO 211942
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
942 AM HST Fri Jun 21 2024

.SYNOPSIS...
High pressure far north of the islands will maintain gusty trade
winds through early next week. Passing showers will favor
windward slopes, especially during nights and mornings. Although
some some light rainfall could occasionally spread leeward, most
leeward locations will remain dry.

&&

.DISCUSSION...
High pressure centered roughly 900 miles north of Kauai remains
firmly in place, producing a stable and gusty trade wind regime
across the islands. Mid-level ridging is limiting inversion
heights to roughly 5,000 to 7,000 feet, as seen on the early
morning 12z soundings from Lihue and Hilo. Latest satellite and
radar imagery shows a narrow band of shallow moisture moving into
windward areas of the smaller islands, with Kauai receiving the
most rainfall and the Big Island receiving almost no rain over the
past 6 hours.

A modest uptick in wind speeds is possible today as the high to
the north builds slightly. This will lead to borderline Wind
Advisory conditions for 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. Most hires guidance keeps speeds
just below advisory criteria, however, so have held off on
issuing any headlines at this time.

The shallow moisture moving into the western islands will produce
some off-and-on showers for windward and mountain locations
through the rest of today, though generally less than a quarter
of an inch is expected. With the exception of afternoon showers
developing over the Kona slopes of the Big Island, leeward areas
will remain mostly dry.

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 remain mostly dry.
Trade winds will likely decline to moderate levels by Tuesday or
Wednesday as the high to the north weakens and is displaced
eastward.

&&

.AVIATION...
Breezy to locally gusty trade winds will continue across the
region for the next few days. Brief SHRA are expected mainly over
windward and mauka areas. While VFR conds are generally expected
to prevail, we could see some brief MVFR conds in any SHRA.

AIRMET Sierra for mtn obsc remains in effect for windward
locations of Kauai, Oahu, Molokai, Maui, and Big Island.

AIRMET Tango remains in effect for mod low level turb over and
downwind of island terrain due to the breezy trade winds.


&&

.MARINE...
Strong easterly trades and resulting rough seas will continue
into early next week, supporting the Small Craft Advisory in place
for all waters. Guidance shows a slight downward trend in wind
speeds 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 this weekend with the head of the fetch aimed at
the islands within the 170 to 190-degree directional band. Given
the shorter travel distance, surf could trend up late next week.

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 today.
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 Sunday for all Hawaiian
waters-

&&

$$

DISCUSSION...Vaughan
AVIATION...Walsh
MARINE...TS