629
FXHW60 PHFO 121948
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
948 AM HST Wed Aug 12 2026

.SYNOPSIS...
Moderate to locally breezy trade winds will continue today,
followed by gradual strengthening Thursday into Friday. Mostly dry
conditions will persist through Friday with occasional passing
showers over windward and mauka areas. However, by the weekend the
main weather concern will be related to the potential tropical
development of 93C, currently around 900 miles east-southeast of
the Big Island. Residents and visitors should prepare now for
potential tropical cyclone impacts this weekend. For the latest
development regarding 93C, please monitor www.hurricanes.gov.

&&

.UPDATE...
No major forecast changes this morning. We`re continuing to see
mostly light showers on the east side of the islands. Scattered
showers with the trade winds are still expected at times into
Friday, primarily impacting windward and mauka areas. Dry
conditions and increasing winds will lead to high wildfire risk on
Friday. We`re continuing to monitor potential tropical cyclone
development late this week, with impacts possible over the
weekend.


&&

.PREV DISCUSSION...
Issued at 345 AM HST Wed Aug 12 2026
This morning, the latest regional satellite imagery shows several
areas of low clouds and a few embedded showers moving into
primarily the central islands from Oahu to Maui from the east.
Despite this, rainfall amounts overnight have been fairly light.
Although an updated 12z sounding was unavailable at Lihue
overnight, the early morning sounding from Hilo showed a strong
inversion around 5000 to 6000 feet, which is supportive of the
drier conditions being observed. Mostly dry conditions are
expected to continue through the rest of the work week, with a few
scattered showers riding in with the trade winds from time to
time affecting primarily windward and mauka areas.

As previous discussions have mentioned, the primary forecast concern
over the next 7 days will be related to the area of potential
tropical development that is around 900 miles east-southeast of
the Big Island as of 3am HST. The National Hurricane Center (NHC)
continues to report that the area is conducive for tropical
development, with a 90 percent chance of development, likely
within the next day or so. While confidence remains fairly high
for at last portions of the state to be impacted by a tropical
cyclone this weekend, the severity of these impacts remains highly
uncertain early this morning, as the system has not yet fully
developed into a tropical cyclone. Once the system becomes better
organized, we should have higher confidence in the weather
impacts. Interests within the main Hawaiian Islands should
closely monitor for forecast updates and prepare for the potential
impacts described below.

FIRE WEATHER...
Fire weather concerns will increase on Friday ahead of any
potential tropical cyclone`s arrival. Winds will begin to
strengthen while a dry and stable air mass with low relative
humidity moves  overhead. This combination of lower relative
humidity and increasing wind speeds will likely lead to high
wildfire risk.

STRONG AND GUSTY WINDS...
Winds could strengthen further on Saturday, though the timing, direction,
and magnitude of the strongest winds remain highly dependent on
the eventual track and intensity of the system. Even if the center
of the system remains away from the islands, the north semicircle
of the storm will likely produce damaging winds. Due to the great
uncertainty at this time, it is likely that the current
deterministic forecast is under-doing winds at some locations,
while potentially over-doing the winds at others. The specifics on
winds impacts will become more clear as further development
occurs over the next 24 to 48 hours.

HEAVY RAINFALL...
This system could bring periods of heavy rainfall, particularly
across east and southeast-facing slopes. Orographic enhancement
could result in locally higher rainfall totals where moist
tropical flow interacts with island terrain. If heavier rainfall
persists over the same locations, flash flooding and rapidly
rising streams are possible. Again, the location of heaviest rain
and any bands that would move through the islands will be highly
dependent on the system`s track. The current forecast favors the
Big Island and islands of Maui County as having the highest
rainfall potential, but this is subject to refinement over the
next few days as further development occurs.

LARGE AND ROUGH SURF...
The developing system is expected to generate a large easterly
swell as it moves northwestward across the Central Pacific. Surf
may build along east-facing shores from east to west as the system
approaches, with warning level surf of 15 feet or larger possible
into the weekend.

&&

.AVIATION...

Breezy trade winds will continue much of the week and may
strengthen slightly through at least Thursday. Scattered showers
will focus over mostly windward and mountain areas, and remain
light due to an area of drier air anticipated to move through the
islands today.

AIRMET Sierra is currently in affect for mountain obscuration for
the north to east side of Maui. Molokai and Big Island maybe added
to this as an area of low level clouds moves from the east.

AIRMET Tango for low level moderate turbulence over and
immediately south and west of mountain ranges will also be
watched closely as wind speeds are expected to gradually
strengthen today through Thursday.




&&

.MARINE...
Issued at 345 AM HST Wed Aug 12 2026
High pressure to the far northeast will slowly drift into a
position just north of the Hawaiian Islands into the weekend,
producing moderate to locally strong trade winds across the
region. A Small Craft Advisory (SCA) was extended in time through
Thursday afternoon for the windier waters and channels around Maui
and the Big Island.

The weather pattern may change significantly this weekend as we
continue to watch for a developing tropical cyclone currently in
an area roughly 800-900 NM east-southeast of the Big Island.
Potential impacts are uncertain at this time, as the tropical
cyclone has not yet formed and track guidance remains challenging.
Marine interests should be prepared for potential tropical
cyclone impacts to offshore and coastal marine zones starting
Friday and lasting through the weekend.

Surf along south and west facing shores will continue to remain
elevated as overlapping south swells continue to fill in around
the islands today. Another moderate, long period south swell will
fill in later today through Thursday, with swell energy peaking
south shore surf heights into the High Surf Advisory range on
Thursday. This south swell energy will then slowly fade into
Saturday. In the long range surf outlook, the next decent boost in
south swell energy may arrive by the end of next week (Aug 19th
through 23rd).

Surf along east facing shores will continue to remain moderate and
rough due to continued trade winds. Later in the week, the track
of a developing tropical cyclone will dictate the potential for a
large swell exceeding warning levels from the east to southeast
direction.

Surf along north facing shores will remain flat to tiny through
the week.

&&

.FIRE WEATHER...
Issued at 345 AM HST Wed Aug 12 2026
High pressure to the northeast of the state will maintain
moderate to locally breezy trades over the next few days. A pocket
of drier air is expected to move in today. This dry airmass will
bring afternoon humidities down to near critical thresholds this
afternoon, but wind speeds will be the limiting factor as far as
fire danger is concerned, since they are expected to remain in the
moderate to locally breezy categories today. Fire weather
concerns could increase further on Friday as the trade winds
strengthen to strong speeds. The combination of dry weather and
breezy to locally strong trade winds will create near-critical
fire weather conditions on Friday. Temperature inversion heights
will range between 4,500 to 6,000 feet over the next few days.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory until 6 PM HST Thursday for Alenuihaha
Channel-Big Island Leeward Waters-Big Island Southeast Waters-
Maalaea Bay-Pailolo Channel.


&&

$$

DISCUSSION...Vaughan
AVIATION...Almanza
MARINE...Bohlin