Kekaha, Hawaii Weather Forecast Discussion

210
FXHW60 PHFO 090148
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
348 PM HST Mon Sep 8 2025
.SYNOPSIS...
An uptick in humidity and mainly windward showers is expected
tonight as weakening Hurricane Kiko approaches the region. Kiko
will pass north of the islands Tuesday and Wednesday, disrupting
the trade winds, producing areas of heavy rainfall, and
generating large surf along east facing shores. Moderate trade
winds and a typical pattern of windward rainfall will return on
Thursday.
&&
.DISCUSSION...
Light to moderate trade winds and rather stable conditions are
holding on this afternoon as weakening Hurricane Kiko approaches
the region from the east. Moisture on the outer fringes of the
circulation around Kiko are moving onto windward Big Island and
Maui. Little rainfall has yet to occur in these areas, but dew
points have pushed up into the mid to upper 60s. Just to the west,
a narrow slot of subsidence has maintained dry conditions with
dew points in the lower 60s from west Maui to Oahu. Over on Kauai,
a small batch of low level moisture moved onto windward slopes
this morning, and an upper-level trough centered just to the west
has produced enough instability to generate clouds and scattered
showers across much of the island.
For tonight, moisture and increased humidity will spread westward,
and the persistent light to moderate trade winds will produce
showers along mainly windward slopes. Kauai will likely experience
diminished rainfall this evening as the current batch of showers
moves westward, followed by higher rain chances toward sunrise as
the deeper moisture finally reaches the western end of the island
chain.
Kiko is forecast to pass north of the islands as a tropical storm
Tuesday and Wednesday, and while no direct impacts are expected, a
moist and humid airmass with dew points in the low to mid 70s
will bring a chance of heavy showers. Although there appears to be
no organized moisture over the state on Tuesday, precipitable
water within the tropical air mass will be around 1.50 to 1.75
inches, and a weak upper-level trough over the region will help
to erode or eliminate the inversion. As Kiko moves to the north
of island chain, trade winds will be weakened or disrupted
completely, allowing afternoon sea breezes to produce clouds and
spotty showers over land. Some showers may become locally heavy,
and we cannot rule out a brief thunderstorm, mainly over interior
Big Island. As Kiko passes north of Kauai on Wednesday, moderate
trade winds will build over the Big Island and Maui in the
afternoon. Heavy showers will still be possible, especially over
the western half of the island chain.
As Kiko moves off to the northwest of the state on Wednesday
night and Thursday, moderate trade winds and a ridge aloft are
expected to build in from the east. The resulting stable
conditions will bring a drier air mass with a typical pattern of
windward rainfall and dew points dropping back into the mid 60s.
&&
.AVIATION...
Light winds with land and sea breezes can be expected today and
tomorrow as Tropical Cyclone Kiko passes north of the island
chain. A dry slot can be seen on satellite imagery for much of the
state with the exception of Kauai, where few clouds can be seen
out ahead of the moisture surrounding Kiko.
Moisture associated with Kiko will fill in tonight and bring a
modest increase in clouds and showers to mostly windward and
mountain areas. Tomorrow afternoon could see some locally heavy
showers with MVFR and embedded IFR conditions in afternoon
showers over island interiors. The exact location of where these
heavier showers would setup are uncertain, however hires models
have been indicating that the slopes of the Big Island, Maui, and
the leeward mountains of Oahu and Kauai could receive pop up
afternoon heavy showers.
AIRMET Sierra for mtn obsc is in effect for Kauai. Conditions
should improve by the evening as the plume of moisture moves on.
An expansion of this AIRMET is likely later in the evening into
tomorrow morning as moisture from Kiko moves into the area.
&&
.MARINE...
A weak trough northwest of the state will continue to drift
westward, away from the state this evening. Moderate to locally
fresh trade winds returned this morning and will continue to
persist through tonight. As Tropical Cyclone Kiko passes to our
north on Tuesday, trade winds are expected to weaken with gentle
to moderate background northeast flow.
Hurricane Kiko, which was located approximately 300 NM ENE of
Hilo this afternoon continues to track northwest in the Central
Pacific. According to the latest forecast from the National
Hurricane Center, Kiko is expected to enter the eastern offshore
waters this evening as a Tropical Storm. Kiko will then continue
to weaken and move west-northwest through the offshore waters. A
Tropical Storm Warning is in effect for the offshore waters with
Tropical Storm conditions expected over the E and NE offshore
waters tonight through Wednesday. The latest forecast for the
coastal waters, shows strong confidence for Kiko to stay north of
the coastal waters. Although no wind impacts are expected over the
coastal waters, a quick rise of wave heights are expected tonight
into Tuesday as Kiko passes.
Latest buoy observations from Hilo showed a rise in energy across
the 12-14 second spectral bands this morning, but since then the
energy has been steady this afternoon. With Kiko expected to make
its closes approach to the Hawaiian Islands during the next 24-36
hours, we should see a quick rise in wave heights starting with
the eastern half of the state tonight and the western half of the
state on Tuesday. Although peak surf heights are expected to be
short-lived, a rapid rise of east swell should produce dangerous
conditions along east facing shores. A High Surf Warning has been
issued for the Big Island, Maui, and Molokai starting tonight and
for Oahu and Kauai starting Tuesday. Surf heights are expected to
peak at low end warning thresholds tonight for the Big Island,
late tonight into Tuesday morning for Maui County and Tuesday mid
day into the afternoon for Oahu and Kauai.
The current medium period south-southwest swell will slowly decline
this afternoon before another reinforcing swell out of the south-
southwest is expected on Tuesday. This should help maintain surf near
or slightly above the summer average throughout the first half of the
week. Additionally, multiple small pules of northwest swell energy
will generate small surf along north facing beaches throughout the
week. A short-lived northeast swell is possible for select exposures
as Kiko passes to our north.
&&
.FIRE WEATHER...
Decreased winds and increased humidity with higher chances for
rainfall are expected through Wednesday as Tropical Cyclone Kiko
passes northeast and north of the state. A return to moderate and
stable trade winds will occur on Thursday, though conditions are
expected to remain below critical fire weather thresholds.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Warning from 6 AM to 6 PM HST Tuesday for Olomana-
Kauai East-Kauai South-East Honolulu-Koolau Windward.
High Surf Warning until 6 PM HST Tuesday for Maui Windward West-
Molokai Windward-Molokai Southeast-Windward Haleakala-Kipahulu-
Big Island Southeast-Big Island East-Big Island North.
&&
$$
DISCUSSION...Wroe
AVIATION...Tsamous
MARINE...Kino
FIRE WEATHER...Wroe

NWS HFO Office Area Forecast Discussion