325
FXHW60 PHFO 130142
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
342 PM HST Wed Jun 12 2024

.SYNOPSIS...
Broad high pressure north of the state will drive moderate to
breezy trade winds through the week. Showers will be focused over
windward areas, and leeward communities will be rather dry,
though the Kona slopes Big Island will experience clouds and
showers each afternoon and evening.

&&

.DISCUSSION...
A wetter trade wind weather pattern will linger over most areas
into tonight. Broad surface high pressure located nearly 1,000
miles north of Kauai is maintaining moderate to locally breezy
trade winds, and a mid-level ridge continues to produce stable
conditions, capping low clouds at around 7,000 to 8,000 ft. In
contrast to the dry weather Monday and Tuesday, there was a
noticeable increase in showers overnight, as a shallow area of
open celled cumulus clouds with precipitable water in excess of
1.5 inches moved in on the trades. Since then, many windward sites
picked up between a quarter to a half of an inch of rainfall.
Most leeward areas have experienced little accumulation, while
sites on the Kona slopes of the Big Island have picked up between
a tenth to a quarter of an inch. Expect this shower regime to
linger into the evening and diminish late tonight.

Only subtle changes are due this week. Recent runs of the GFS and
ECMWF are showing the surface high moving into the northeast
Pacific, while a firm trailing surface ridge holds north of
Hawaii. As a result, expect moderate to locally breezy trade winds
to continue, with some increase possible by the middle of next
week. Precipitable water is forecast to lower back to around
seasonal average by Thursday, suggesting a slight decrease in
showers and typical June conditions. A resilient mid-level ridge
will maintain stability, even as an upper-level trough develops
over the region this weekend. The GFS and ECMWF are hinting that
this upper trough may strengthen early next week, but it is too
far out to confidently expect any increase in shower activity.

&&

.AVIATION...
Moderate to breezy trade winds will persist across the Hawaiian
Islands over the next couple of days. Clouds and showers will
favor windward and mauka areas, especially overnight, and bring
brief periods of MVFR conditions to those areas. Otherwise, VFR
conditions should generally prevail.

AIRMET Sierra for tempo mountain obscuration is in effect for
windward portions of the smaller islands this afternoon due to
more persistent low clouds and showers. This AIRMET may be needed
for windward areas along portions of the island chain overnight
into tomorrow morning.

&&

.MARINE...
Fresh to strong easterly trades will continue through the
weekend, as the surface ridge remains north of the area. This
supports the Small Craft Advisory (SCA) continuing for the
windier channels and waters around Maui County and the Big Island
each day. A slight uptick is expected Thursday into Friday, which
could expand the SCA to other zones.

Surf along south facing shores will slowly ease through Thursday
as the current south-southwest swell fades. Expect a mix of this
fading south-southwest swell and a small, medium-period southeast
swell through Thursday. A fresh, long-period south swell is
expected to arrive Thursday night into Friday, then peak late
Friday into Saturday. This swell should produce advisory level
surf Friday into Saturday then gradually decline Sunday into early
next week.

Surf along north-facing shores will remain up above the
summertime average (flat) through a good portion of the week and
into next week as small, short-period north to north-northwest
swells move through.

Surf along east-facing shores will remain small and choppy over
the next several days due to limited trade wind fetch upstream of
the islands. A slight increase is possible on Friday as the winds
upstream of the state strengthens.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Saturday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

&&

$$

DISCUSSION...Wroe
AVIATION...Farris
MARINE...Kino