670
FXHW60 PHFO 281942
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
942 AM HST Mon Apr 28 2025

.SYNOPSIS...
A moist unstable airmass will remain in place during the next few
days, with sea breezes allowing for the development of locally heavy
showers and a few thunderstorms each afternoon. Land breezes will
keep most shower activity over the coastal waters or near the coast
at night. Trade winds are expected to return Wednesday, reaching
breezy levels Friday through the weekend, along with a more typical
windward and mauka shower pattern.

&&

.DISCUSSION...
Currently at the surface, a weak trough of low pressure is located
near Kauai, while a 1031 mb high is centered far northeast of the
island chain. Winds remain light across the state, with land breezes
present in most areas this morning. Infrared satellite imagery shows
partly cloudy conditions across most of the state, with mostly clear
island interiors. Radar shows scattered light showers over east and
southeast facing slopes of the Big Island and elsewhere over the
coastal waters.

The weak trough of low pressure will remain nearly stationary over
the smaller islands today through Tuesday. Winds will change little
during this time, with land and sea breezes dominant over most of the
state. The airmass will remain moist and unstable over the next few
days as a deep upper low dives southward over the state. This will
bring some locally heavy showers and a few thunderstorms to the island
chain, particularly during the afternoon hours and favoring interior
and leeward areas. The chance for heavy showers and thunderstorms will
be most widespread on Tuesday as the center of the low (and greatest
instability) is at it`s closest approach. Land breezes will tend to
push activity out over the coastal waters or areas near the immediate
coast at night.

The surface troughing over the islands will gradually dampen out
during the middle and latter part of the week as high pressure builds
to the north. This should allow a gradual return and strengthening
of the trade winds across the state around midweek, with the trades
reaching breezy levels Friday through the weekend. The upper low will
move off to the east of the islands during the second half of this
week, with ridging firmly in place by week`s end. This will allow
for more stable conditions and a return to more typical trade shower
pattern, with activity focusing mainly over windward and mauka areas
through the weekend.

Volcanic emissions and light background southeast flow will keep vog
in place over most of the state through Tuesday. The returning trades
should clear the vog out of the smaller islands by late Wednesday.

&&

.AVIATION...
A weak surface trough slowly passing over the islands will keep the
background wind flow light and variable for the next couple days.
Sea breezes and inland cloudiness will prevail in the afternoon
and early evening hours and weak land breezes and mostly clear
skies in the late night and early morning hours.

A corresponding upper level low will generate air mass instability
and encourage shower development statewide. MVFR/IFR CIG or VIS
are possible in locally heavy downpours or thunderstorms,
especially over island interiors both this afternoon and tomorrow
afternoon.

No AIRMETs are currently in effect or anticipated at this time.

&&

.MARINE...
A trough of low pressure near Kauai continues to weaken the high
pressure ridge over the eastern Hawaiian Islands. This boundary is
expected to slowly shift east over the next 24 hours in tandem
with an upper level disturbance moving overhead, increasing the
potential for showers and thunderstorms over the coastal and
offshore waters. Light and variable winds will continue through
Tuesday. Trades will build back in from Wednesday onward as a high
pressure system builds to the north of the main Hawaiian Islands.

A small northwest swell will slowly fade into Tuesday. Surf along
north and west facing shores should remain near or below average
levels for this time of year. By Thursday, a moderate long period
north- northwest swell is expected to arrive, producing surf above
the seasonal average (6 feet for the month of May). This north-
northwest swell will slowly decline over the weekend.

Multiple small south swells will maintain small background southerly
energy through Tuesday. A bump up in south- southwest swell energy
will arrive on Wednesday, peak Thursday producing moderate surf,
and then slowly fade through the weekend. However, a mix of reinforcing
south-southwest swell and new south- southeast swell energy will
arrive this weekend and should help maintain surf near or above
the summer average (5 feet). Then early next week, another pulse
of south-southwest swell energy will arrive.

Weak upstream trade wind flow will keep surf on the small side for
east facing shores. An increase is expected by Wednesday as the
trade winds return. Trade winds should strengthen on Friday with
rough and choppy surf expected along east facing shores through
the weekend.

&&

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

&&

$$

DISCUSSION...TS
AVIATION...Bedal
MARINE...Kino/Farris