586
FXHW60 PHFO 040146
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
346 PM HST Mon Nov 3 2025

.SYNOPSIS...
A moderate easterly trade wind flow will gradually become more
stable tonight and Tuesday, as an area of low pressure west of
Kauai moves away from the area. Showers will favor windward
slopes, and while most leeward areas will be rather dry, spotty
afternoon showers will develop along the Kona slopes of the Big
Island. Trade winds will start to weaken on Thursday and will
likely be disrupted on Friday, when a passing upper level
disturbance is expected to produce isolated interior showers
during the afternoon. A weakening front may move down portions of
the island chain this weekend.

&&

.DISCUSSION...
The trade wind flow is slowly stabilizing as an upper-level low
west of Kauai drifts away from the region. This feature triggered
some impressive showers on Kauai early Sunday, but a ridge aloft
building in from the east is producing increasingly stable
conditions this afternoon. Scant shower activity has been
observed over windward areas from Kauai to Molokai today, but a
small pocket of moisture dropped less than a quarter of an inch of
rainfall on windward Big Island and Maui and fueled a few showers
over interior sections of the Big Island. Expect this shower
activity to diminish overnight, with light rainfall accumulations
over windward slopes.

A moderate and rather stable trade wind flow will prevail by
Tuesday. High pressure at 500 mb centered overhead will lead to a
strengthening inversion that will produce stability, but the
departing upper low will send a shield of high clouds over the
island chain. The surface ridge north of the state will remain
essentially unchanged and generate moderate trade winds. Guidance
shows little organized moisture in the trade flow, which points
toward modest windward rainfall along with a few afternoon showers
across the leeward slopes of the Big Island. Drier and
increasingly stable conditions favor a decrease in showers on
Wednesday.

Trade winds will start to decline on Thursday, as an approaching
North Pacific front weakens the surface ridge north of Hawaii.
The ridge aloft over the islands will hang on through the day,
suggesting continued stable conditions and limited rainfall.

Trade winds will likely become disrupted Thursday night and
Friday as the front advances. A fast-moving upper-level trough
passing over the island chain will lead to some instability, but
moisture may be lacking. As a result, day time sea breezes will
likely lead to spotty interior showers Friday afternoon.

The shallow and weakening front may reach Kauai sometime Saturday
and drift over other portions of the island chain Sunday. Timing
with this feature remains highly uncertain, and the GFS and ECMWF
show the above mentioned upper-level trough lifting to the
northeast with ridging aloft build over the islands during this
time. Since the frontal band will be very weak with no upper
support, rainfall will likely be confined to windward and north
slopes with little threat for flooding.

&&

.AVIATION...
Moderate trades will continue for the next couple of days as
ridge builds north of the state. High clouds will stream in from
the southwest tonight. Low clouds and showers will remain over
windward and southeast Big Island this evening bringing brief
mountain obscurations along these slopes. No AIRMETs expected
tonight, but will monitor for lower ceilings, visibilties and
extensive mountain obscuration on the Big Island.

&&

.MARINE...
A surface ridge of high pressure far north of the state will
maintain moderate to fresh trade winds through tonight. A trough
and upper level disturbance west of the offshore waters will
continue to produce isolated thunderstorms across the south and
west offshore waters for a few more days. Moderate to fresh trade
winds will strengthen slightly into the fresh to locally strong
range from Tuesday through Thursday then steadily decline Thursday
night as the ridge shifts southeastward towards the state in
advance of an approaching cold front.

A large reinforcing short to medium period north swell that
quickly filled in last night peaked this morning and will continue
to decline through Tuesday. With the large north swell declining
this afternoon, surf heights have dropped below High Surf Advisory
thresholds for select north and east facing shores and seas have
also dropped below Small Craft Advisory thresholds.

A gale low currently passing far north of the state will send the
next large medium period north-northwest swell. This swell should
arrive Tuesday night into Wednesday and peak late Wednesday. Surf
heights should reach advisory thresholds along north and west
facing shores by Wednesday afternoon. Advisory level surf could
hold into parts of the day Thursday, but the swell should be on a
steady decline. A reinforcing north-northwest swell is possible on
Friday, which should help maintain moderate surf on Friday.

In the long range, a deep low pressure system is expected to
develop to our north and northeast Friday into Saturday. This low
will likely send a large north-northeast (020-030 degree) swell
late this weekend. Due to the swell angle, heavy surges will be
possible along north facing harbors such as Kahului and Hilo on
Sunday.

Surf along select east facing shores will remain elevated due to
the declining north swell through tonight. A large north-northeast
swell on Sunday could bring advisory level surf along east facing
shores on Sunday. South facing shores will remain small
throughout this week. A small long- period south- southwest swell
is possible Friday into the weekend with a larger out of season
south swell possible early next week.

&&

.FIRE WEATHER...
Relative humidity values and winds will be below critical fire
weather conditions into the weekend. A weak inversion near the
Big Island and Maui will strengthen and become better defined near
7,000 feet Tuesday then build down to around 5,000 feet Wednesday.

&&

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

&&

$$

DISCUSSION...Wroe
AVIATION...Foster
MARINE...Kino
FIRE WEATHER...Wroe