240
FXHW60 PHFO 220137
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
337 PM 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
and mountain areas, especially during nights and mornings.
Although 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 this afternoon, producing a stable and gusty
trade wind regime across the islands. Latest satellite and radar
imagery shows isolated to scattered light showers moving into
windward and mountain locations, primarily over the western
islands of Kauai and Oahu. Farther east, fewer clouds and showers
are noted upstream of and over windward Big Island. Gusty trades
have been observed across the islands today, particularly in
typically windier areas and valleys. However, speeds have
generally hovered below Wind Advisory criteria.

Guidance suggests that a subtle shortwave moving over the state
tonight could increase windward and mauka shower activity through
early Saturday morning. Otherwise, the overall weather pattern
will remain largely unchanged through the weekend with high
pressure remaining in place to the north. Trades on Saturday are
expected to be similar to those experienced today, so have opted
not to issue a Wind Advisory at this time.

Breezy trade winds and a typical summertime rainfall pattern will
prevail 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 trades 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 remains in effect for mtn obsc for windward
locations of Kauai, Oahu, Molokai, and Maui.

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 currently lifting northeastward toward the Aleutians.
On its heels is a gale- to storm-force low, currently a couple
hundred miles east of 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