Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 151301
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
301 AM HST Fri Mar 15 2024

.SYNOPSIS...
Persistent light showers along and behind a weakening front will
affect windward terrain of the Big Island and to a lesser extent
Maui County through Saturday. Meanwhile moderate north to
northeast winds will allow cloud cover to gradually decrease and
cooler drier air to filter southeastward down the island chain.
Moderate trade winds will persist Sunday through next Thursday,
with fairly typical, albeit drier than normal, trade wind weather
prevailing.

&&

.DISCUSSION...
Currently at the surface, a weakening cold front is in the
vicinity of the Big Island, while a 1022 mb high is centered
around 900 miles northwest of Kauai. Moderate to locally breezy
northerly winds persist across the island chain early this
morning. Infrared satellite imagery shows considerable cloudiness
across the state, with mostly cloudy to overcast conditions in
most areas. Radar imagery shows a few showers moving into windward
sections of Kauai and Oahu, while more persistent showers continue
to affect north facing slopes of Maui County and the Big Island.
Main short term focus revolves around rain chances and cloud cover
trends.

The cold front will remain nearly stationary and gradually
dissipate in the vicinity of the Big Island today and tonight.
Meanwhile, weak high pressure will slide northeast, well to the
north of the islands through Saturday. Moderate to locally breezy
northerly winds will shift northeast and ease into the light to
moderate range today through Saturday. Ridging will strengthen
north of the islands Sunday and Monday, boosting the trades back
to moderate levels. The ridge will persist north of the state
keeping moderate trades blowing through the middle of next week,
with a new high building northwest of the islands potentially
boosting trades to breezy levels Thursday.

A Wind Advisory remains in effect for the high elevation summits
on the Big Island through 6 AM Saturday. The latest model
guidance shows the potential for warning level winds on the Big
Island summits late today or tonight, and the advisory may
eventually need to be upgraded to a High Wind Warning.

As for the remaining weather details, persistent showers will
continue to affect north and northeast facing slopes and coasts of
Maui County and the Big Island this morning, with some gradual
improvement expected across Maui County by late in the day.
Meanwhile, shower activity should remain light and limited to
windward slopes on Kauai and Oahu. Cloud cover should gradually
decrease across Kauai and Oahu today, while Maui County and the
Big Island appear to remain rather cloudy, particularly in
windward areas.

The remnant moisture band from the dissipated front will linger
near the Big Island Friday night and Saturday, allowing showers to
persist over windward Big Island and to a lesser extent windward
Maui. Meanwhile, mostly dry conditions will continue on Oahu and
Kauai. There remains some mixed signals in the model guidance with
respect to boundary layer moistening from Sunday through Thursday,
but the general idea appears to be a return to a more typical,
albeit drier than normal, trade wind pattern across the island
chain.

&&

.AVIATION...
High pressure continues to build in from the west as a front
across the state drifts eastward. North winds will continue to
spread bands of showery low clouds across the islands. Expect MVFR
conditions in showers, mainly across the central islands. Cloudy,
but VFR conditions will dominate TAF sites elsewhere.

AIRMET Sierra remains in effect for occasional mountain
obscuration across portions of all islands through this morning.
This AIRMET will likely be needed through the rest of today.

No other AIRMET are in effect or are expected.

&&

.MARINE...
A weakening cold front will continue to move over the far
southeast portions of the coastal waters this morning. High
pressure to the northwest of the islands will gradually drift east
as moderate to locally strong north-northeast winds will persist
through Saturday. Winds are expected to remain mostly below Small
Craft Advisory (SCA) thresholds through early next week although
SCA level seas will impact all zones with the exception of waters
south of the Big Island as the current large northwest swell peaks
throughout the day. Trade winds will veer to the east, ease into
the light to moderate range this weekend, and hold through the
middle of next week as a new high builds northwest of the islands.

A long period, large to extra-large northwest swell will continue
to fill in this morning. Observations at the nearshore PacIOOS
Buoy 51201 show a sharp rise early this morning, and is expected
to peak this morning over the smaller islands. A High Surf Warning
(HSW) is out for the north and west facing shores of the smaller
islands, and north facing shores of Maui through today. Due to the
size and west angle, west facing shores of the Big Island are
under a High Surf Advisory (HSA) through today as well. The swell
is expected to decline through the tonight but remain elevated
into Saturday as a HSA will likely replace the HSW this
afternoon. This also translates to pulling back zones from the
SCA due to seas dropping below 10 feet over leeward zones.

A reinforcing northwest swell should arrive late Saturday night,
keeping moderate sized surf along north and west facing shores
through early next week. Another long period northwest swell
reinforcement may push surf up to HSA levels Wednesday of next
week.

South shore surf will remain tiny through Saturday. A south swell
arriving Sunday should produce a slight increase in the surf that is
expected to persist through Monday. East shore surf will also remain
small through early next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Warning until 6 PM HST this evening for Niihau-Kauai
Leeward-Waianae Coast-Oahu North Shore-Maui Windward West-Kauai
North-Molokai Windward-Molokai North-Molokai West-Maui Central
Valley North-Windward Haleakala.

High Surf Advisory until 6 PM HST this evening for Kona-Kohala.

Wind Advisory until 6 AM HST Saturday for Big Island Summits.

Small Craft Advisory until 6 AM HST Saturday for Kauai Northwest
Waters-Kauai Windward Waters-Kauai Channel-Oahu Windward Waters-
Kaiwi Channel-Maui County Windward Waters-Alenuihaha Channel-Big
Island Windward Waters-Big Island Leeward Waters.

Small Craft Advisory until 6 PM HST this evening for Kauai
Leeward Waters-Oahu Leeward Waters-Maui County Leeward Waters-
Maalaea Bay-Pailolo Channel.

&&

$$

DISCUSSION...Jelsema
AVIATION...Powell
MARINE...Shigesato


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