513
FXHW60 PHFO 011359
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
359 AM HST Sat Nov 1 2025

.SYNOPSIS...
Moderate trade winds with stable conditions will continue today,
with showers focused over windward and mauka areas. Trades will
weaken tonight as a front and its associated upper level feature
approach from the north. This will bring unsettled weather,
particularly for Kauai, Sunday into Monday. Drier conditions are
expected through much of the remainder of the new week as high
pressure reestablishes itself north of the islands.


&&

.DISCUSSION...
While the grids have been updated to reflect the latest National
Blend of Models (NBM) solution, the updates didn`t change much in
the forecast.

High pressure to the northeast will continue to bring trade winds
to the region today, along with showers limited to the typical
windward and mauka locations. A front to the north of the islands
will be sinking southward. This will lighten winds over the
islands by tomorrow, with winds shifting to the southeast near the
Big Island and Maui, and more to the northeast near Kauai and Oahu
tonight and tomorrow. The surface front is expected to reach Kauai
late Sunday evening before moving away from the islands. This will
bring an increase in moisture, resulting in an uptick in shower
activity, particularly over the western islands.

The upper level trough associated with the surface front will
help to provide some instability as the upper level system sinks
closer to the islands behind the front. The global models remain
in good agreement with a mid to upper level low developing along
the upper level trough later today. The last couple runs of the
GFS showed little change in the placement of the upper low. The
ECMWF solution is a little weaker than the GFS, but not enough to
impact confidence levels. The southerly flow associated with the
upper feature will pull additional moisture northward over the
islands. The heaviest showers are expected to be over or near
Kauai late Sunday into Monday.

That all being said, there remains a great deal of uncertainty
with the placement of the upper low and the associated moisture.
Little change in the NBM Probabilistic Quantitative Precipitation
Forecast (PQPF) 90th percentile since yesterday afternoon. With
500 mb temperatures expected to be near -10C to -11C, the chance
for thunderstorms remains in the forecast for Sunday, for Kauai
and Niihau and surrounding coastal waters.

High pressure is expected to rebuild into the region from Tuesday
through Thursday, allowing trades to become reestablished across
the region. With drier air working into the region and stable
conditions returning, showers will once again be confined to
mainly windward and mauka areas.


&&

.AVIATION...
Moderate trade winds will continue today, but weaken tonight as a
frontal system approaches the state from the north. Trade wind
showers today will be focused over the windward and mauka areas of
the islands. These showers will bring periods of MVFR conditions
to those areas, otherwise VFR conditions will prevail into
tomorrow.

No AIRMETs are in effect, and none are expected today.

As the above mentioned front approaches Kauai Sunday
afternoon/evening, an AIRMET for mountain obscuration and/or IFR
may be needed.


&&

.MARINE...

High pressure to the northeast will maintain moderate to locally
fresh trade winds through this morning before decreasing through
the day as a front northwest of the islands moves southeast
towards the region and displaces the ridge. Isolated thunderstorms
will be possible for the northwestern coastal waters by Sunday as
the front approaches the western end of the state. The front is
expected to stall and then get pushed to the west as high
pressure builds back in by Monday, increasing trade winds to
moderate to locally fresh speeds. Winds are expected to remain
below SCA levels until Tuesday or Wednesday.

The approaching front is expected to enter the offshore waters
later today, with strong breezes expected over the extreme
northwest portion of the offshore waters tonight and Sunday. The
front will also bring the possibility of thunderstorms to the
offshore waters.

Surf along north facing shores will continue to increase through
the morning in response to a medium to long period NNW swell
(330) filling into the region with surf expected to reach High
Surf Advisory (HSA) levels by the afternoon. Surf will hold at
HSA levels through tonight, and a HSA is in place for that time
frame for N and W facing shores. Another NNW swell (320-330) is
expected to fill in on Sunday, followed by a medium period NNE
swell Sunday evening, associated with an approaching front with
near- gale winds, that will primarily impact the western end of
the state. This mix of swells may maintain HSA level surf through
Sunday before gradually fading early next week. A moderate to
large swell is then possible around the middle of next week.

Surf along east facing shores will remain small to moderate through
Sunday morning, and then may be impacted by the medium period NNE
swell mentioned above. South shore surf will remain small through
early next week before building slightly mid to late week as a
long period SSW swell (190) fills in across the region.



&&

.FIRE WEATHER...
Increased relative humidity values and decreasing trade wind
speeds will keep fire weather conditions below critical thresholds
into next week.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory from noon today to 6 AM HST Sunday for Niihau-
Waianae Coast-Oahu North Shore-Maui Windward West-Kauai North-
Molokai Windward-Molokai North-Molokai West-Maui Central Valley
North-Windward Haleakala.


&&

$$


DISCUSSION...M Ballard
AVIATION...M Ballard
MARINE...Farris
FIRE WEATHER...M Ballard