455
FXHW60 PHFO 100656
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
856 PM HST Thu Jan 9 2025

.SYNOPSIS...

Enhanced showers will move along windward and mauka areas tonight
with down trend Friday, expect for the kona slopes of the Big
Island. Generally fair weather is expected over the weekend, but
some showery weather conditions may linger around windward Big
Island and east Maui through Saturday, especially during the
overnight and early morning hours. A drier more typical trade
wind pattern is expected Sunday into the first half of next week.

&&

.DISCUSSION...

The upper level trough axis now centered over the state and
continues to dig southward. East of this trough axis, we can
expect unsettled weather to continue through this evening with
conditions stabilizing west of the trough axis. Scattered showers
with pockets of heavy showers can be see on radar and satellite
just upstream of Oahu, Maui County and the Big Island and are
moving westward along with the moderate tradewinds. This area is
expected to move onshore overnight and during the early morning
hours Friday and may even clip Kauai. Some of the heavier showers
are producing brief periods of rainfall rates of 1 inch per hour
and will closely monitor these showers overnight in case a Flood
Advisory may need as showers persist over windward and mauka
areas.

Friday, the upper level trough is expected to cut off over or just
south of the Big Island. At the surface, a ridge of high pressure
far north of the state will generate moderate to locally breezy
trade winds. For most of the time, we should see our standard
trade wind showers mainly over windward and mauka area of Maui
County and the Big Island, but some pockets of enhanced showers
will be possible due to the upper level low nearby. The Kona
slopes of the Big Island could also see some heavier showers
during the afternoon on Friday. A slight chance of thunderstorms
remains around Maui through Friday morning with a slight chance of
thunderstorms over the Kona slopes Friday afternoon.

For the weekend, the trough axis will elongate and shift to a more
SW to NE orientation over or just east of the Big Island which
could keep enhanced tradewind showers in the forecast into the
weekend especially upstream of the Big Island and east Maui.
Generally fair weather is expected especially over Kauai and Oahu.

For the first half of next week, the upper level low will weaken
and shift eastward as a ridge builds overhead. This ridge will
bring drier and more stable conditions over the state. A brief
weakening of the trades will be possible on Monday as a front
passes far north of the state, but moderate trades should return
on Tuesday. Long range ensemble guidance show a potentially
strong front moving through the state towards the end of next
week. Stay tuned for more details.


&&

.AVIATION...
The potential for localized heavy showers and a few thunderstorms
will continue for parts of the state through Friday as an upper
trough closes off into an upper low around the Big Island. The
mostly likely location for this activity will remain over the
windward waters and slopes from Oahu to the Big Island with
the trades in place, as well as the leeward slopes of the Big
Island during the peak heating hours Friday afternoon.

AIRMET Sierra for mountain obscuration is now in effect from
Oahu to the Big Island for windward areas. Kauai may need to be
included at some point through the overnight hours.


&&

.MARINE...
A trough near Kauai will shift westward and gradually dissipate
tonight and Friday, allowing moderate to locally strong trades to
fill in across the island chain. Moderate to locally strong
trades should then hold in place through the weekend, with a
slight easing possible again early next week.

A Small Craft Advisory (SCA) remains in effect for most marine
zones through 6 am Friday due to winds, seas, or a combination of
the two. The SCA will likely be extended into the weekend with the
morning forecast package for the typically windy waters around
Maui and the Big Island, and dropped for the other marine zones.

The current large northwest swell will gradually decline tonight
through Saturday. A High Surf Advisory remains in effect for most
north and west facing shores through 6 AM Friday. This advisory
may need to be extended through the day Friday with the morning
forecast package. A new long-period northwest swell will arrive
late Saturday and Saturday night, peak Sunday into Sunday night,
then lower on Monday. This swell will give a boost to surf along
north and west facing shores, but will likely remain below
advisory levels. A pair of overlapping northwest swells will then
move through early next week, with the first arriving early
Monday, peaking late Monday and Monday night. The second will
build Monday night, peak Tuesday then gradually decline through
next Thursday. These overlapping swells may bring another round
of advisory level surf to most north and west facing shores Monday
afternoon through Tuesday night.

East shore surf not exposed to the series of northwest swells will
remain very small tonight, then gradually rise Friday through
Saturday as the trades return over and upstream of the islands.
Surf along east facing shores will then hold relatively steady
Sunday, then lower a bit Monday through Wednesday as the trades
ease slightly. East shore surf could trend lower again late next
week as an approaching front disrupts the trades over the
islands.

South shore surf will remain very small through the middle of next
week. An out of season long-period south swell may move through
the islands late next week, bringing a sizable boost to south
shore surf.


&&

.FIRE WEATHER...

No critical fire weather conditions are expected through next
week. Some drier conditions will be possible early next week, but
trade winds should remain below strong speeds.


&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 AM HST Friday for Niihau-Kauai
Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kona-
Kohala-Kauai North-Molokai Windward-Molokai North-Molokai West-
Maui Central Valley North-Windward Haleakala-Big Island South.

Small Craft Advisory until 6 AM HST Friday for Kauai Northwest
Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-
Oahu Windward Waters-Kaiwi Channel-Maui County Windward Waters-
Maalaea Bay-Pailolo Channel-Alenuihaha Channel-Big Island
Windward Waters-Big Island Leeward Waters-Big Island Southeast
Waters.


&&

$$


DISCUSSION...Almanza
AVIATION...Gibbs
MARINE...Jelsema
FIRE WEATHER...Almanza