Volcano, Hawaii Weather Forecast Discussion

309
FXHW60 PHFO 031333
AFDHFO
Area Forecast Discussion
National Weather Service Honolulu HI
333 AM HST Fri Oct 3 2025
.SYNOPSIS...
Gentle to moderate east-southeast winds will continue through
Saturday morning in response to an approaching cold front in the
North Central Pacific, allowing localized daytime sea breezes and
overnight land breezes to continue. Moderate trades are forecast
to build back late Saturday and remain into early next week as a
new high builds north of the state.
&&
.DISCUSSION...
Gentle to moderate east-southeast winds will continue through
Saturday morning in response to an approaching cold front in the
North Central Pacific. The front will stall out north of the
islands and so will not have a direct impact on our weather.
12Z soundings show relatively stable conditions, with the
inversion between 6000 to 7500 feet and precipitable water values
of 1.54 inches at Lihue and 1.29 inches at Hilo.
Current radar and satellite data show low clouds and scattered
showers mostly passing by the islands offshore, but occasionally
coming onshore as plume showers impact islands downstream (to the
northwest). Main impacts overnight were concentrated across
Molokai, Lanai and windward Oahu. Showers should taper off through
the morning hours before clouds build up this afternoon over all
island interiors as sea breezes dominate due to wind blockage from
the Big Island. The plume showers will likely set up again
tonight and impact the smaller islands at times, otherwise land
breezes will work to keep showers offshore.
Latest models indicate easterly trades will build back into the
region Saturday afternoon and continue into early next week as a
new surface high develops and strengthens far to the northeast of
the state. Clouds and showers will again focus back to windward
and mauka areas. A broad surface trough will develop northeast of
the state around Monday and slowly track westward across the
island chain through the middle part of next week. Winds will
again taper off and put us in a land and sea breeze regime, but
forecast confidence is low for placement of any showers as this
feature moves through the state.
&&
.AVIATION...
East southeast flow with embedded showers will continue this
morning. Land breezes have kept most showers offshore, but plumes
developing off Molokai will bring showers to windward and
southeast Oahu this morning, where AIRMET Sierra is posted for
tempo mountain obscurations above 2500 feet. VFR conditions
prevail elsewhere with isolated MVFR ceilings and visibilities
around the showers. AIRMET Sierra could also be issued for any of
the smaller islands through the morning if the plume showers push
into the islands.
For this afternoon, expect to see cloud build ups over island
interiors as sea breezes dominate due to wind blockage from the
Big Island. AIRMET Sierra could also be possible across
leeward/interior sides of the islands this afternoon due to the
extensive clouds and showers. Low level wind shear possible over
PHOG today.
Land breezes will clear out islands tonight with the possibility
of plume showers lining up across the smaller islands and
overriding the land breezes and bring additional showers to
southeast slopes.
&&
.MARINE...
Surface high pressure northeast of the state will continue to
drift east a front moves north of the area. Light to moderate
east southeast winds have developed over the forecast waters and
will hold today giving way to localized land and seabreezes over
leeward waters. High pressure will build in from the northwest
allowing moderate to locally fresh trade winds to return Saturday
through Sunday. A trough may develop northeast of the state early
next week, weakening winds to light and variable.
The current small medium period northwest (310-320 deg) swell
from Tropical cyclone Neoguri will decline today. A moderate,
medium period north northwest (330 deg) swell generated from the
current low located far north northwest of the islands is expected
to fill in on Saturday, peak Sunday just below High Surf Advisory
(HSA) criteria for north facing shores, and slowly fade into
early next week. Another small medium to long period swell from
the northwest (320 deg) is expected to fill in Monday, peak
Tuesday and decline through the middle of next week.
The current small, long period southwest (210 deg) swell will
continue will peak today before slowly declining into early next
week. Another small, long period southwest swell may arrive late
Sunday and build into early next week before subsiding. Surf along
east- facing shores will remain below average into early next
week with the a slight boost Saturday into Sunday as moderate to
fresh trades briefly return.
&&
.FIRE WEATHER...
Wind speeds and humidity will remain below critical fire weather
thresholds for the next seven days. Temperature inversion heights
across the state will range from 6000 to 7500 feet today.
&&
.HFO WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
DISCUSSION/AVIATION/FIRE WEATHER...Foster
MARINE...Shigesato

NWS HFO Office Area Forecast Discussion