152
FXHW60 PHFO 010644
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
844 PM HST Mon Aug 31 2026

.SYNOPSIS...
Breezy trades will continue into Wednesday. Showers will
generally favor windward and mauka areas, particularly during the
overnight through early morning hours each day. Tropical Storm
Lowell is about 630 miles southeast of the Big Island this
evening, and is forecast to pass south of the Big Island late
Wednesday into Thursday. Trade winds are expected to become strong
and gusty as early as Wednesday afternoon, and continue into
Friday as Lowell passes south of the state. The forecast remains
uncertain for Labor Day weekend, with the potential for Lowell and
Karina in the the vicinity of the state.


&&

.DISCUSSION...
No changes to the forecast with the evening package, and not
expecting any large scale changes with the morning package.

Clouds and showers continue to be carried in on the trade wind
flow, and as a result are focused over the windward and mauka
areas. A surface trough about 450 miles east of the islands will
continue to move towards the islands over the next 24 hours and
weaken, however moisture from that trough will reach the islands
tomorrow night and be one of the reasons showers are expected to
be on the increase.

Tropical Storm Lowell is about 630 miles southeast of the Big
Island this evening, and the latest forecast from the National
Hurricane Center (NHC) has Lowell strengthening to a hurricane
overnight. The latest track and cone for Lowell has the system
passing south of the islands Wednesday night through Friday. Outer
rainbands and moisture from Lowell could begin to spread across
the islands Tuesday, increasing chances of passing trade wind
showers, however the bulk of moisture will likely pass south of
the state. Additionally dewpoint temperatures are expected to
exceed 70 degrees, which will make the atmosphere muggier than
normal. Trade winds will stay breezy due to a strong surface high
remaining far north of the area.

Overall expect an uptick in passing showers over the next few
days, due to the moisture from the trough mentioned above Tuesday
night, and moisture loosely associated with Lowell passing
through the state.

The latest forecast from the NHC has Lowell passing a little over
300 miles south of the Big Island Wednesday night into Thursday
as a category 3 Major Hurricane. While probabilities for tropical
storm force winds remain low over the state, the tightening of
the pressure gradient over the islands will likely produce very
windy and gusty trade winds as early as Wednesday afternoon
through Friday. Winds could reach advisory thresholds with wind
gusts over 50 mph possible during this time.

As we head into the weekend, as Lowell exits, our focus will shift
more to Hurricane Karina which is currently about 1600 miles east
of the Big Island. The latest forecast from NHC for Karina brings
it about 600 miles east of the Big Island on Saturday. We will
continue to monitor Karina over the coming days to discern its
potential impacts on the state.

The forecast spread drastically increases over the Labor Day
weekend into early next week as an upper level trough/low develops
north of the state. Latest 12Z run of the Google DeepMind (GDM)
model continues to shows Lowell taking sharp northward turn over
the weekend. While confidence has increased on Lowell passing
south of the state during the week, the forecast still remains
very uncertain over Labor day weekend into early next with several
ensemble members of the GDM showing a sharp northward turn. Also
during this time, we could see Karina within the vicinity of the
islands late this weekend. Please keep an eye out on the
hurricanes.gov page for the official NHC forecast for Lowell and
Karina.



&&

.AVIATION...
Moderate to breezy trade winds will persist through this 01/06Z -
02/06Z period. Occasional MVFR decks and brief organized showers
riding within the trades will generally favor windward exposures
and higher terrain. Otherwise, VFR conditions will prevail.
Tropical Cyclone Lowell is forecast to pass a couple of hundred
miles south of the island chain later this week. On this track,
late week trade winds will strengthen as the pressure gradient
tightens between Tropical Cyclone Lowell and high pressure to the
far north.

AIRMET Sierra is in effect for tempo mountain obscurations for
north through east sections of Kauai, Maui and Big Island due to
persistent low clouds and shower coverage. AIRMET Sierra will
remain in effect through tonight for these islands.

AIRMET Tango remains in effect for moderate low level turbulence
south through west downstream of higher terrain. AIRMET Tango
will likely be in effect for the foreseeable future.


&&

.MARINE...
A strong surface high will remain nearly stationary far north of
the Hawaiian Islands this week, keeping moderate to locally
strong trade winds in place. Tropical Storm Lowell, now in the
Central Pacific, is forecast to intensify into a hurricane tonight
and will track very close to or move into the southern offshore
waters, bringing possible hurricane conditions from Wednesday
into Thursday. There is still some uncertainty with the forecast
track of Lowell, especially closer to this weekend as the cyclone
begins to gain latitude, which will have significant impacts on
the wind, wave, and surf forecast for the region. Regardless of
Lowell`s final path, trade winds will increase by Wednesday
afternoon through Friday as a result of the gradient between high
pressure to the north and Lowell to the south. By this weekend,
Hurricane Karina, approaching the region from the east, will
increasingly be a factor in the forecast of seas and surf as well.

A small, long-period south swell will hold through tonight before
a moderate south swell arrives on Tuesday. This swell will build
Tuesday morning and then peak on Wednesday, bringing surf heights
to just below advisory thresholds. This swell will then gradually
decline through the rest of the week. Also by Wednesday, medium-
period energy from Lowell could start filling in across south and
southeast shores. South shore surf is likely to be elevated, but
stay below advisory levels through at least Friday. Beyond that
point, the surf forecast is highly dependent on the eventual track
and intensity of Lowell, which has the potential to be a
significant source of south to southwesterly swell through this
weekend and into next week.

Trade wind swell energy will keep elevated surf heights along all
east facing shores through the coming week. On Tuesday, a medium-
period east swell arrives from Hurricane Karina that will build
through the week and could push east shore surf to advisory
thresholds by this weekend and into next week.


&&

.FIRE WEATHER...
Breezy trades continuing through Tuesday, are expected to
strengthen further as early as Wednesday afternoon through Friday
as Tropical Storm Lowell passes south of the islands as a
Hurricane. Strong gusty winds over 50 mph will be possible across
select areas during this time. While fuel conditions are not at
critical levels due to abundant rainfall we have received over the
past several weeks, moderate fire danger will be possible for
areas mainly due to very windy conditions. Dewpoints are expected
to increase in the upper 60s and low 70s by Tuesday afternoon and
hold through the week, keeping minimum humidities in the 50s for
the most part. A few leeward areas could still see humidities down
into the mid 40s especially on Thursday as a pocket of dry air
moves in. The exact track of Lowell remains uncertain and thus
potential for meaningful rainfall remains uncertain at this time.
The inversion will hover between 5500 ft and 6500 ft the next
couple of days.


&&

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


&&

$$

DISCUSSION...M Ballard
AVIATION...Blood
MARINE...Quesada
FIRE WEATHER...M Ballard

NWS HFO Office Area Forecast Discussion