Volcanic Ashfall in Hawaii, January 24, 2026

Area Forecast Discussion
National Weather Service Honolulu HI
900 AM HST Sat Jan 24 2026

.SHORT TERM UPDATE...
Unstable weather day expected today due to an upper level trough
moving through the state. Expect showers to increase later this
morning into the afternoon especially across Oahu, Maui County and
the Big Island. Moderate to locally heavy showers will be
possible and due to the slower storm motion, some localized
flooding will also be possible today. Shower activity and the
threat of heavy rain should diminish this evening into the
overnight hours as land breezes develop. Over the summits of the
Big Island, afternoon snow showers are expected and a Winter
Weather Advisory has been issued.

&&

.SYNOPSIS...
Moisture and instability will linger over the islands today,
though will gradually decrease by the end of the weekend. Winds
will weaken and veer east-southeasterly today, then become light
and southerly on Sunday, allowing land and sea breezes to dominate
and drive afternoon showers over interior and leeward areas.
Forecast confidence decreases early next week as one or more weak
fronts approach the state, though limited upper-level support
should keep rainfall impacts modest.

&&

.PREV DISCUSSION.../ISSUED 356 AM HST Sat Jan 24 2026/

The 12z upper air soundings from Lihue and Hilo show that a moist
and somewhat unstable air mass remains in place across the island
chain early this morning as the inversion has eroded a bit
compared to 24 hours ago. A late evening ASCAT pass revealed that
light to moderate easterly trade winds have briefly returned to
the state overnight as surface high pressure continues to slide
eastward away from the state. Showers and low clouds during the
past twelve hours or so have primarily favored windward and mauka
areas, particularly for the island of Maui yesterday evening, and
now predominantly Oahu early this morning. Meanwhile, ample
moisture aloft is resulting in scattered high clouds moving across
the region.

As high pressure continues to shift east ahead of the next front
approaching from the northwest, winds are expected to gradually
veer east-southeasterly today, then weaken further and turn
southwesterly across the western half of the state by Sunday. As
the winds decrease, this will set up a daytime sea breeze and
overnight land breeze regime across the islands. Meanwhile, the
upper-level trough that has been supplying instability will slowly
move off to the east, allowing atmospheric stability to increase
from west to east as mid-level ridging builds into the region.
With that said, moisture and instability will linger today as the
upper trough moves over and eventually past the region. This will
keep showers in the forecast, and isolated thunderstorms have also
been introduced across eastern portions of the island chain for
the afternoon. Additionally, with cold temperatures and deep
moisture over the summits, snow showers and freezing fog may
emerge again this afternoon as daytime heating sparks convection
over the Big Island.

By Sunday, instability and moisture will be decreasing, and
confidence in thunderstorm chances remains too low to include in
the forecast at this time. Isolated to scattered showers will
still be possible over interior and leeward areas during the
afternoon where sea breeze induced surface convergence commences.

An unusual amount of uncertainty exists in the forecast early next
week, as global models still offer wildly different solutions
regarding a potential front moving into or through the area. The
ECMWF, for example, brings a front into the western part of the
island chain by late Sunday night, then shows it quickly moving
down the island chain on Monday. This scenario offers a wetter
solution and breezy northeasterly winds following the frontal
passage. Meanwhile, the GFS keeps the front north of the state,
with the island chain remaining in a drier pattern with lighter
winds persisting. In any case, even if the front does move into
the islands, with mid-level ridging forecast to persist over the
state, there would be limited upper-level support.

The rest of the week next week looks to remain fairly dry with
light southeasterly winds returning for much of the week. This
would once again favor a land and sea breeze regime ahead of
another potential front towards the end of next week.

AVIATION...
Isolated showers continue over the eastern islands with most
locations remaining in VFR conditions. Easterly winds will remain
light and gentle through the day and may veer to the southeast
over the western end of the state by the afternoon. With the light
winds, the chance for seabreeze and land breeze patterns may set
up over interior sections of the islands. Drier conditions are
expected as some MVFR cigs/vsbys may affect interior portions of
the islands in the afternoon but predominantly VFR conditions are
expected statewide.

Currently, no AIRMETs are effect.

MARINE...
A high pressure system currently north of the state will drift
eastward over the weekend as another front approaches the state
from the northwest. Moderate trades will veer from a more
southeasterly direction today, then become light southerlies from
tonight into Sunday. Winds should become light enough for near
shore land and sea breezes to develop during this time. The tail
end of the cold front will likely move into the northwest waters
late Sunday into Monday with fresh north to northeast winds
blowing in north of the front. There are still some uncertainty on
how far southeast the front will move into the islands, which
will alter the reach and extent of both northerly winds and rain
showers over island waters. Highest chances are that the forward
motion of this weak cold front stalls out near Kauai waters by
Monday morning.

The current medium period north-northwest (330-340 degree) swell
will continue to decline today. Surf heights will remain elevated
as a series of small overlapping northwest swells will pass
through the Hawaii region through the weekend into early next
week. The first pulse should arrive late Saturday and peak on
Sunday, followed by another pulse late Monday. A slightly larger
north-northwest (330 degree) swell is expected Tuesday into
Wednesday. In the long range, there is potential for a large long
period northwest swell building to warning levels impacting north
and west facing shores towards the end of next week.

Surf along east facing shores will remain small into next week
due to the lack of persistent trade winds locally and upstream.
South facing shores will remain nearly flat through the weekend. A
tiny long-period south-southwest swell may produce a slight boost
to south shore surf heights from late Sunday into Tuesday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory from noon today to 6 AM HST Sunday for
Big Island Summits.

&&

UPDATE...Kino
PREV DISCUSSION...Vaughan/Shigesato/Bohlin