697
FXHW60 PHFO 261319
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
319 AM HST Wed Nov 26 2025

.SYNOPSIS...
A weak high pressure ridge will hover over the Hawaiian Islands
through the weekend. A combination of large scale stability under
the ridge and southeasterly wind flow will keep the smaller
islands in the leeward rain shadow of the Big Island mountains;
leading to minimal shower activity statewide. A weak cold front
approaches the islands from the northwest and stalls out near
Kauai by next week Tuesday, increasing shower trends over the
western half of the state.

&&

.DISCUSSION...
Fairly stable and shallow cumulus clouds appear over the Hawaii
Region in this morning GOES IR satellite imagery. A hot dark spot
shows up over the Kilauea Volcano due to the large heat emissions
from the recent volcanic eruption cycle. Farther to the northwest
of the islands a cold front passes through the Central Pacific
basin, keeping a weakened ridge firmly in place over the island
chain. Recent eruptions of Kilauea will pull up VOG (Volcanic
smOG) today, appearing as hazy skies for all islands. University
of Hawaii VOG model shows these hazy skies lingering through at
least Thursday.

The weak high pressure ridge over the islands will produce
strong and stable subsidence, downward vertical atmospheric
motions, across the entire state through the weekend. Subsidence
driven temperature inversion heights were measured this morning at
2 AM HST (12Z) from our upper air weather balloon soundings at
around 5,000 feet at both Lihue and Hilo. At these low levels the
temperature inversion will tend to cap vertical cloud growth,
significantly reducing clouds and limiting showers. The position
of this ridge over the islands will also keep the state in a light
southeast wind flow pattern. These light large scale winds will
allow for local scale daytime onshore sea breezes to develop over
each island.

The larger scale southeasterly winds will also produce a rain
shadow effect, as clouds approaching the state will flow around
the Big Island and clouds will drift more parallel to the smaller
island mountain ranges. This means less clouds lifting
orographically over island mountains, resulting in even lower
shower activity. A few stray showers are still possible, however
any showers that develop will likely be brief and amounts will be
light. Once exception to this rule will be the eastern slopes of
the Big Island and eastern slopes of Maui where scattered shower
activity remains in the forecast, mainly during the overnight to
early morning hours.

The weather pattern changes early next week, as a cold frontal
system approaches the state from the northwest. The forward motion
of this frontal cloud band will stall and diminish near Kauai from
next week Tuesday to Wednesday. Southerly winds ahead of this
frontal band will pull up very humid air over the western islands,
shower activity will increase over Niihau, Kauai and Oahu during
this time period. Wet weather trends will favor the southern and
western slopes of Kauai and Oahu, as the southerly winds will lift
the tropical moisture over the island mountains. Stay tuned as
this pattern remains in the extended outlook forecast period and
these island by island weather impacts will likely evolve over
time.

&&

.AVIATION...
Light to moderate E-ESE trade winds will continue into Thursday.
This will allow periods of daytime sea breezes to occur over most
terrain sheltered leeward areas. MVFR conditions may briefly
develop within passing showers over exposed windward and mauka
regions, and along sheltered leeward and interior areas during
daytime seabreezes. Otherwise, VFR will prevail.

No AIRMETs in effect, and none are expected.

&&

.MARINE...
A surface ridge, parked just north of the state, will allow for
mainly gentle to moderate east to east southeast flow across the
waters through the end of this week. However, winds are forecast
to ramp up for the typical windy areas around Maui and the Big
Island late Thursday into Friday and a Small Craft Advisory may
be needed. Waters located in the of the lee islands will be more
sheltered, and thus lighter flow with a nocturnally driven
land/sea breeze pattern close to the coasts. Similar conditions
prevail through the weekend as a frontal system stalls north of
the islands.

A series of rather impressive long period northwesterly swells
will affect the waters through the forecast period. Forerunners
from the first, medium to large, northwesterly (320-340 deg)
swell showed up at Waimea Bay buoy early this morning. Swell
energy will ramp up through the day, peak tonight, then slowly
ease during the day Thursday. Thus, a High Surf Advisory will
remain in effect through Friday morning for most exposed north and
west facing shores of the smaller islands. Combined seas during
the peak of the swell will approach 10 ft and a Small Craft
Advisory (SCA) for rough seas may warranted for the waters
northwest of Kauai and Oahu.

Over the next several days, models rapidly deepen a low in the
north Pacific, roughly 1,500 to 2,000 nm northwest of Kauai. A
significant fetch of gale to storm force winds associated with
this low will be pointed down the great circle route towards the
island chain and produce the next big swell event. Guidance
depicts this long period, northwest swell first reaching the
waters by mid- day Saturday, then ramping up quickly thereafter.
The peak of the event currently appears to be Saturday night into
Sunday with the potential for the first of the season extra-large
northwest (310-320 deg) swell. If current trends come to
fruition, a High Surf Warning for exposed north and west facing
shores would be needed, in addition to a SCA for rough seas.

Surf along east facing shores will remain small through the
weekend due to the lighter winds. Expect manly tiny surf along
south facing shores with minor background energy.

&&

.FIRE WEATHER...
Wind speeds and humidity levels remain below critical fire
weather thresholds through the weekend. Only minimal shower
activity lingers in the forecast. Temperature inversion heights
near the Big Island and Maui will range from 5,000 to 6,000 feet
today.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 4 AM HST Friday for north and west facing
shores of Niihau, Kauai, Oahu, Molokai, and north facing shores of
Maui.

&&

$$

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