998
FXHW60 PHFO 161301
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
301 AM HST Wed Apr 16 2025

.SYNOPSIS...
A daytime sea breeze and overnight land breeze pattern will set up
during the next couple days, before the trades gradually return
and strengthen Friday through early next week. A convective shower
pattern is expected today through Friday, with showers favoring
interior and leeward areas during the day, and areas near the
coast at night. A disturbance aloft moving over the islands could
bring some heavier showers and thunderstorms tonight through
Friday. A return to a more typical trade wind pattern favoring
windward and mauka areas is expected over the weekend into early
next week.

&&

.DISCUSSION...
Currently at the surface, a cold front is located around 350
miles northwest of Kauai, while a 1031 mb high is centered around
2250 miles north-northeast of Honolulu. Winds have diminished
across the western islands, with land breezes present in most
areas, while light to moderate east-southeast trades prevail in
unsheltered areas over the eastern end of the state. Infrared
satellite imagery shows partly cloudy conditions in most areas,
with a few areas with a bit more cloud coverage. Meanwhile, radar
imagery shows isolated to scattered showers are moving into
windward slopes and coasts, with a few showers spilling leeward as
well. Main short term focus revolves around trade wind trends and
rain chances.

A ridge to the north of the islands will gradually weaken and
erode today, as a cold front approaches from the northwest. As a
result, sea breezes will be common over the western islands,
while light to moderate east-southeasterly trades persist over
the eastern end of the state. The front will stall out northwest
of the area tonight and Thursday, with broad troughing developing
across the island chain. Land and sea breezes will remain common
during this time, with background light to moderate east-southeast
winds confined to areas around the Big Island. The trough appears
to dampen Friday through the weekend, allowing a gradual return
and strengthening of the trades which will continue into early
next week.

As for the remaining weather details, a transition over to a
convective pattern is expected today, with showers favoring the
island interiors during the afternoon and evening hours, and areas
near the coast at night. This pattern will linger into Friday
when the trades will begin to return. Meanwhile, an upper level
trough will move slowly eastward across the state tonight into
Friday, with 500 mb temperatures of -12 to -13C and precipitable
water values increasing to around 1.5 inches. This will likely
result in some heavier showers, particularly during the afternoon
and evening hours. In addition, isolated thunderstorms will also
be possible as the cold pool aloft moves eastward across the
state. A more typical trade wind pattern may slowly return late
Friday through early next week.

&&

.AVIATION...
Moderate easterly trades will gradually veer and ease today
continuing to bring the potential for SHRA and low cigs to
windward and mauka locations. Sea breeze development as convergent
boundaries may be a source of clouds and showers to leeward areas
of some of the smaller islands. A disturbance aloft moving over
the islands could bring some heavier showers and potentially
isolated thunderstorms Thursday. MVFR conditions will be possible
in any showers, but overall, VFR conditions will prevail today
before the potential for widespread MVFR conditions on Thursday.

While the ongoing eruption of Kilauea is currently paused, there
is degassing occurring. This could cause some hazy conds across
the islands. It is not enough to impact vsbys at this time and not
currently in any TAFs but was worth a mention.

No AIRMETs in effect.

&&

.MARINE...
Trades have eased and shifted out of the east-southeast overnight
due to a front approaching from the northwest. Over the western
end of the islands, the weakening winds will allow a land and sea
breeze pattern to develop near the coasts, which will persist into
Friday as the front stalls off to the west. For the eastern end,
light to moderate east to southeast breezes, with localized fresh
pockets, will likely persist, particularly around the Big Island.
A return to fresh to strong easterly trades is possible by the
weekend as the ridge reestablishes to the north.

As trades diminish, chances for heavy showers and thunderstorms
will increase. The main threat will develop around Kauai and Oahu
late tonight, slowly spread to the entire island chain Thursday,
then diminish from west to east on Friday.

Surf along exposed north and west facing shores will continue to
diminish today as a northwest swell moves out. An upward trend is
expected Thursday as a fresh north-northwest arrives and builds
down the island chain. Surf may near the advisory levels for
exposed north and west facing shores Thursday night into Friday as
this swell peaks. A downward trend is then expected over the
weekend, with the swell shifting out of north.

Surf along east facing shores will remain below the April average
through at least Saturday, then steadily rise to around average
by early next week.

Surf along south facing shores will remain small through the
week, with mainly overlapping background south swells moving
through. A larger pulse of south-southwest swell may arrive
Tuesday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$

DISCUSSION...Jelsema
AVIATION...Shigesato
MARINE...Gibbs