557
FXHW60 PHFO 011356
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
356 AM HST Mon Dec 1 2025

.SYNOPSIS...
An approaching weak cold front will stall out near Kauai on
Wednesday and continue to keep the high pressure ridge entrenched
directly over the Hawaiian Islands. Large scale stability under
this ridge and drier southeasterly wind flow will minimize shower
activity into Tuesday. Clouds and showers along the frontal band
may stall over Kauai by Wednesday, potentially increasing shower
activity over the Garden Isle. Trade winds will build back into
the region and strengthen from Thursday onward, bringing back
periods of passing showers to windward and mountain areas,
favoring the typical overnight to early morning hours.

&&

.DISCUSSION...
Looking into the big picture satellite imagery this morning, a
band of fairly stable stratocumulus clouds are moving up from the
southeast into the Big Island and east Maui. Local radar imagery
shows passing showers over the southeast slopes of both islands.
Farther to the northwest, another weakening cold front approaches
the Hawaii Region. A high pressure ridge remains locked in place
over the island chain, producing stable conditions and light
southeasterly winds. The subsidence temperature inversion heights,
as measured by weather balloon observations from Lihue and Hilo
at 2 AM HST (12Z) this morning, are showing two temperature
inversion levels around 3,000 and 6,000 feet elevation.

These two temperature inversions will continue to serve as a
stable capping force for cloud development, reducing shower
potential statewide. Additional stable dry trends are also due in
part to southeasterly wind flow that places the smaller islands in
a drier rain shadow of the Big Island with clouds tracking more
parallel to island mountain ranges, limiting orographic lifting of
clouds over windward mountains. Lighter large scale winds will
also keep daytime onshore sea breezes going for most areas through
Tuesday. VOG (Volcanic smOG) from the Kilauea Volcano will also
ride into all islands on these drier southeasterly winds. This VOG
will appear as haze affecting all islands today, with some
improving trends from today onward as the low level steering winds
begin to change.

This dry southeasterly wind pattern will continue for most areas
through Tuesday or Wednesday. On Wednesday, medium range model
solutions continue to show changes in our local weather pattern
as a weakening cold front moves near Kauai and stalls. Shower
activity will likely increase over Niihau and Kauai for 12 to 24
hours, until this front breaks apart and drifts westward away from
the islands. Differences between the main operational American
(GFS) and European (ECMWF) remain, with the ECMWF model showing
wetter trends for the islands in Kauai County.

A high pressure system will build in north of the state for the
second half of the week, increasing easterly trade winds across
the region. Expect some southeasterly winds to linger on Thursday
morning, with winds becoming more easterly and stronger from
Thursday night into next weekend. As the ridge over the islands
lifts northward, our typical trade wind shower activity returns
with brief passing showers forecast along windward and mountain
areas, favoring the typical overnight to early morning hours.

&&

.AVIATION...
Light southeasterly flow will continue through Tuesday before
becoming light and variable. Local sea breezes will occur each day
with land breezes developing overnight. Expect mostly VFR
conditions with brief MVFR conditions along exposed southeast
coasts and slopes of the Big Island and Maui early this morning as
a band of low level band of clouds with embedded light to
moderate showers moves through. A thin veil of high clouds will
build over head from west to east through the day.

No AIRMETs are in effect and none are expected.

&&

.MARINE...
A weak surface ridge will remain over the area through Tuesday
and maintain light to moderate southeast background flow. This
pattern will allow for daytime sea breezes and nighttime land
breezes along waters adjacent to the coasts. A slowly declining
large northwest swell will generate seas above Small Craft
Advisory (SCA) levels for exposed waters today and a SCA remains
in effect until noon. Oahu leeward waters were already removed
during this package, due the lowering seas. A cold front is
projected to approach Kauai from the northwest on Wednesday, but
models quickly weaken it into a trough as it retrogrades back
westward, away from the islands. Moderate to locally strong easterly
trade winds will finally return Friday into the weekend as
surface high pressure builds northeast of the area.

The current, large, long-period northwest (320 degree) swell
will slowly decline through the remainder of today. Waimea Bay
Buoy 51201 continues to report swell heights in the 10 to 12 foot
range and the High Surf Warning will remain in effect through
noon today for exposed north and west facing shores of most
islands. Surf is then expected to drop to advisory levels by this
afternoon as the swell energy eases. Another large, long period
northwest swell (310-330 degree) is forecast to fill in on
Wednesday, peak Thursday, then slowly subside on Friday. Surf may
once again approach warning levels.

East shore surf will remain small through Thursday due to weak
winds, then become choppier as trade winds increase Friday through
the weekend. Expect small background swell and surf for south
facing shores.

&&

.FIRE WEATHER...
Rather dry conditions are expected to persist through at least
Tuesday. Winds will be light and variable under a stable land and
sea breeze pattern, keeping weather conditions below critical fire
weather thresholds. Two temperature inversion heights will remain
in place over Maui and the Big Island today, with the lowest
inversion height in the 2,500 to 3,000 foot elevation range and
the higher inversion height in the 6,000 to 6,500 foot elevation
range.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Warning until noon HST today for north and west facing
shores of Niihau, Kauai, Oahu, Molokai, north facing shores of
Maui, and west facing shores of the Big Island.

Small Craft Advisory until noon HST today for Hawaiian coastal
waters and channels exposed to the large northwest swell.

&&

$$

DISCUSSION...Bohlin
AVIATION...Almanza
MARINE...Thomas
FIRE WEATHER...Bohlin