Kapolei, Hawaii Weather Forecast Discussion

472
FXHW60 PHFO 011356
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
356 AM HST Wed Oct 1 2025
.SYNOPSIS...
An unstable band of clouds riding in with the trade wind flow
will enhance shower activity Wednesday morning into Thursday. The
high will shift northeast as a weak front slides north of the
state Thursday onward, weakening winds to light to gentle east to
east southeast flow and allowing for land seabreezes to develop in
the more sheltered areas into the weekend. Moderate trades may
build back over the weekend into early next week as a new high
builds north of the state.
&&
.DISCUSSION...
Ongoing Kilauea eruption will bring localized ashfall and Pele`s
hair south and west of the volcano as well as an increase in vog
around the Big Island. A Special Weather Statement is posted on
our website with more information.
Elsewhere, infrared satellite and radar show an incoming band of
clouds and showers to the east just beginning to impact windward
sides of the islands early this morning. Moderate trade winds will
push this band across the islands today with some lingering
showers tonight as the moisture tracks to the west. The trade wind
inversion is around 7500 feet, but fairly weak due to an upper low
to the northwest, which may allow some showers to become moderate
in intensity and spill over to leeward sides of the islands.
Weakening trade winds will veer from a more east to southeast
direction from Thursday into Friday as a front approaches from the
northwest but stalls and weakens before reaching Hawaii.
Decreasing large scale winds will allow thermally driven local
scale sea breezes to strengthen during the daylight hours over all
islands. Shower trends in this sea breeze pattern will tend to
favor interior and upslope sections of the state each afternoon
before clearing overnight. The latest weather model solutions also
show good chances for converging winds along the leeward sides of
island mountains producing shower bands extending from west to
northwest of each island. These developing shower bands may
briefly enhance rainfall amounts over Oahu and Kauai in this
southeasterly wind regime from Thursday through Saturday.
Moderate easterly trades may build back over the weekend as a new
high builds north of the state but there is still differences
between the GFS and ECMWF model guidance on when and where an
upper level trough will develop that is providing some
uncertainty in the extended forecast.
&&
.AVIATION...
Moderate trades through the forecast period. Low cigs and SHRA
should be mainly focused over windward and mauka locations. MVFR
conds possible in any SHRA otherwise VFR will prevail.
Kilauea has resumed erupting now episode 34. There is potential
for ashfall to occur south and west of the volcano. In addition
an ash cloud has been observed and could reach to FL250. SIGMET
Series Whiskey will be used for volcanic ash.
No AIRMETs in effect.
&&
.MARINE...
Surface high pressure centered far north of the region will slowly
advance east as a trough develops in its wake through Friday. This
will maintain a tight enough downstream pressure gradient to
produce moderate trades the next few days. The gradient will be
disrupted as the trough pulls up northwest of the state by Friday.
This will weaken winds while veering them slightly more south of
east.
As what little energy is left of a small size, medium period north
swell fades this morning, a couple of of small, medium period north
northwest swells will arrive later tonight and Thursday evening.
A more moderate size, medium period northwest swell originating
from a compact North Pacific gale low passing to the north late
Thursday is forecast to arrive this weekend. This swell will build
surf heights to well over head high along many north and west-
facing shores by Sunday.
A series of very small, medium to long period south southwest
swells will keep south-facing shore surf from going completely
flat through the week.
Surf along east-facing shores will remain small within moderate
trades.
&&
.FIRE WEATHER...
Wind speeds will remain below critical fire weather thresholds for
the next seven days. Temperature inversion heights across the
state will range from 7,000 to 8,000 feet.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION/FIRE WEATHER...Foster
AVIATION...Walsh
MARINE...Blood

NWS HFO Office Area Forecast Discussion