770
FXHW60 PHFO 290617
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
817 PM HST Sun Apr 28 2024

.SYNOPSIS...
Moderate trades will prevail over the eastern islands through the
first half of the work week, while lighter trades over the
western islands allow for some leeward land and sea breezes.
Relatively dry weather will persist tonight through Tuesday, with
a few showers affecting windward areas each night and developing
over interior and leeward areas each afternoon. The trades will
rebound Tuesday night and Wednesday, bringing a transition over
to more typical trade wind weather. The trades will become breezy
Thursday through next weekend, and the trade wind showers may
increase as well due to a disturbance aloft moving over the
islands.

&&

.DISCUSSION...
Currently at the surface, a weakening front is located around 500
miles west-northwest of Kauai, while a 1032 mb high is centered
around 1450 miles northeast of Honolulu. Moderate trade winds
prevail in unsheltered areas over the eastern end of the state,
while lighter trades persist over the western islands. Infrared
satellite imagery shows a combination of high and low clouds
resulting in partly to mostly cloudy conditions across the state.
Radar imagery shows scattered showers moving into east and
southeast facing slopes and coasts of Maui and the Big Island,
with a few showers also over the leeward slopes of Maui and the
Big Island. Elsewhere, mainly dry conditions prevail. Main short
term focus continues to revolve around trade wind trends and rain
chances during the next few days.

A front northwest of the islands will gradually weaken into a
trough during the next couple days as it edges slowly eastward.
Little change is expected in the overall wind forecast, with
moderate trades holding on over the eastern end of the state,
while lighter trades prevail over the western islands, allowing
some leeward sea and land breezes to develop. We should see the
trades start to rebound beginning Tuesday night as the trough west
of the state begins to shift slowly westward. Moderate to locally
breezy trades should overspread the island chain by late
Wednesday, with the trades becoming breezy Thursday through next
weekend.

As for the remaining weather details, a band of moisture will
bring some showers into east and southeast facing slopes of Maui
and the Big Island tonight. Elsewhere, shower activity should be
more sparse, with a few showers affecting mainly windward slopes
and coasts, although a few showers will remain possible over
leeward Big Island as well due to the east-southeast boundary
layer flow. Relatively dry conditions should generally prevail
across the island chain Monday through Tuesday. Brief passing
showers will be possible in windward areas each night, with a few
showers developing over interior and leeward areas each afternoon.
A few showers could be a bit more robust over Kauai Monday
afternoon, as some shortwave energy grazes by to the north. We
should see a transition over to more typical trade wind weather
Tuesday night and Wednesday, with wetter trade wind conditions
potentially developing Friday through next weekend as upper
troughing sets up over the state.

&&

.AVIATION...
Light to moderate ESE winds will continue through Monday. Drier
air has filtered in across most of the area, with VFR conditions
expected to generally prevail. However, a N-S oriented low cloud
band is currently moving over the Big Island from the east,
bringing periodic MVFR and even IFR conditions in the heavier
showers. As such, AIRMET Sierra for tempo mountain obscuration is
in effect for the Big Island and may need to be expanded as these
conditions may also develop across windward portions of the
smaller islands later tonight as the cloud band continues to move
westward.

Otherwise, with the lighter ESE flow and decreased cloud cover,
afternoon sea breeze activity is expected across wind- sheltered
areas, with some inland/leeward cloud buildups and a few light
showers possible.

&&

.MARINE...
Surface high pressure far northeast of Hawaii and an approaching
weak front to the northwest will drive breezy east southeast
winds through tonight. A Small Craft Advisory for winds is in
effect for most waters and channels surrounding Big Island, Maui,
and Molokai through tonight. The high will slide east while a low
pressure system will edge closer Monday and Tuesday weakening the
pressure gradient allowing winds to ease. By mid-week, high
pressure will rebuild to the northeast transitioning back to
typically fresh to locally strong trade winds.

North facing shores will remain tiny through the week with tiny
medium period background energy. Surf along east facing shores
will continue to decline as winds begin to taper off Monday and
Tuesday. Surf along south facing shores will see a mix of small,
short- period southeast, and small south-southwest pulse filling
in Monday and Tuesday before easing Wednesday. Surf heights along
the south facing shores should remain near or slightly below
seasonal norms.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 AM HST Monday for Maui County
Windward Waters-Pailolo Channel-Alenuihaha Channel-Big Island
Windward Waters-Big Island Leeward Waters.

&&

$$

DISCUSSION...Jelsema
AVIATION...Farris
MARINE...Shigesato