579
FXHW60 PHFO 011405
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
405 AM HST Mon Sep 1 2025

.SYNOPSIS...
The proximity of a mid-level low northwest of Kauai and lingering
moisture over the western end of the state will enhance shower
activity across this area today. Then as the low lifts and drier
air filters in, drier, more stable conditions can be expected by
Tuesday night, with moderate trades focusing light showers over
windward and mauka areas.

&&

.DISCUSSION...
A mid-level low northwest of Kauai continues to draw up some mid-
level moisture from the southwest and provide modest instability
over the western end of the state today into Tuesday. Meanwhile, a
weak surface trough embedded within the trade wind flow is
aligned with a band of enhanced low-level moisture that is also
moving across the western end of the state today. As a result,
scattered showers, a few of which may be briefly heavy, will be
possible mainly over Kauai and Oahu today. While the instability
is expected to linger into tomorrow, the band of enhanced low-
level moisture will be shifting west of the state, so drier
conditions are expected as compared to today. Then by Tuesday
night, the low begins to lift northwestward, allowing mid-level
ridging to build back across the area. This will bring a
transition to more stable conditions with decreasing shower
coverage statewide.

At the surface, moderate trade winds will persist through most of
the week as seasonably weak high pressure holds north of the
islands. Compared to Sunday, slightly stronger trades will limit
sea breeze development, though isolated leeward and interior build
ups are still possible each afternoon. Overall, low clouds and
showers will favor windward and mauka slopes, primarily overnight
and during the early mornings, with drier conditions prevailing
leeward. Late into the week and weekend, no significant changes
are expected, with moderate trades and a fairly typical trade wind
weather pattern continuing.

The National Hurricane Center is currently issuing advisories on
Tropical Storm Kiko in the Eastern Pacific. According to their
latest forecast, they have it strengthening into a hurricane as it
continues on a mostly westward track over the next several days
and crosses into the Central Pacific. At this time it`s too early
to tell what, if any, impacts this system might have on the local
weather across the state.

&&

.AVIATION...
Light to moderate trade winds will allow localized sea breezes to
develop in sheltered leeward locations today, bringing clouds and
showers over some leeward and interior areas. Tropical moisture
moving across the islands combined with some weak instability
aloft may help to enhance today`s shower activity, with periods
of MVFR possible. Otherwise, VFR should prevail. Drier conditions
are expected tomorrow as the area of tropical moisture pushes
west of the state.

AIRMET Sierra for mountain obscuration is in effect for windward
portions of Kauai and Oahu this morning.

&&

.MARINE...
A ridge of high pressure north of the state will remain displaced
to the south in response to large low far to the north. This will
maintain moderate trades through most of the forecast period,
with some localized sea breezes, especially across leeward waters.

Surf along south facing shores will continue to decline through
today as the swell fades, returning to background levels for most
of the week. Surf along north facing shores will see a boost
today due to a small, short-to medium-period swell. This swell
will quickly be overshadowed by longer period energy out of the
northwest starting this afternoon and peaking on Tuesday. Surf
will increase again from the influence of this swell, but remain
below advisory levels. A reinforcing pulse out of the north should
arrive around the same time the northwest swell arrives. A mix of
north and northwest swells are expected to continue through
Thursday. Below average surf is expected to continue along east
facing shores persisting through early next week.

Peak monthly high tides, combined with water levels running higher
than predicted, may lead to minor flooding along the shoreline and
in low-lying coastal areas toward the end of next week. Coastal
flooding may be possible around the daily afternoon peak tide.

&&

.FIRE WEATHER...
Moderate trades prevail for the remainder of week delivering
limited showers windward and mauka. As the resident area of
enhanced low-level moisture exits to the west of the state by
Tuesday, dewpoints return to typical values in the upper 60s. Even
with this drying trend, winds look to be the limiting factor,
helping to keep the state from meeting critical fire weather
thresholds.

&&

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

&&

$$


DISCUSSION...Farris
AVIATION...Farris
MARINE...Walsh
FIRE WEATHER...Farris