High Surf in Hawaii, March 1 to 2, 2023

Area Forecast Discussion
National Weather Service Honolulu HI
840 PM HST Tue Feb 28 2023

.SYNOPSIS...
Wet and windy trade wind weather will persist over the next
several days, with enhanced showers and thunderstorms possible
across the eastern half of the state. Expect the most rainfall
over windward slopes of the Big Island. Trade winds should
gradually decrease Friday into the weekend as a front approaches
from the northwest. This front will likely bring an increase of
heavy showers, especially across leeward areas during the first
half of next week.

&&

.DISCUSSION...
Strong high pressure north of the state will drive blustery trade
winds for the next few days. Satellite loop shows an upper low
just northeast of the Big Island which is enhancing trade wind
showers and triggering isolated thunderstorms. This upper low will
move closer to the state over the next several days.

The afternoon Hilo sounding showed an unstable airmass with no
capping trade wind inversion, thanks to the upper low. Expect
isolated thunderstorms across portions of Maui and the Big Island
due to this instability. Highest rainfall will be over windward
slopes of the Big Island and possibly east Maui during the next
several days. Strong and gusty trade winds will continue through
Wednesday and will increase slightly tonight through Wednesday.
Wednesday looks to be the windiest day of the week with gusty
winds of over 50 mph possible especially in areas downwind of
terrain. As a result, an array of Wind Advisories and High Wind
Warnings remain in effect through Wednesday afternoon. These may
be extended if conditions warrant.

Trade winds will gradually weaken Thursday through the weekend
and could become light and variable by Sunday as a front begins to
approach the state from the northwest. Overall, expect a decrease
in shower activity and lighter winds this weekend. Models show an
active weather pattern setting up for next week as a front
approaches Monday into Tuesday, likely triggering periods of heavy
rainfall and isolated thunderstorms. With prefrontal winds
shifting to the southwest, the rainfall focus will shift toward
leeward areas.

&&

.AVIATION...
A strong high pressure system far north of the Hawaiian Islands
will keep strong and gusty trade winds in the forecast through
Thursday. An unstable upper low will anchor just east of the Big
Island over the next few days. A combination of unstable
conditions and strong winds will lift clouds up island mountain
slopes and produce periods of showers over all windward and
mountain areas, with more isolated to scattered showers over
leeward sections. Expect periods MVFR conditions in showers along
north through east sections of each island.

AIRMET Sierra remains in effect for mountain obscurations
windward areas of most islands. This AIRMET will likely continue
through early Wednesday morning and then decrease in coverage by
noon HST Wednesday.

AIRMET Tango remains in effect for low level moderate to isolated
severe turbulence over and downwind of all island mountains. AIRMET
Tango also remains in effect for strong surface winds across the
entire state. These AIRMETs will likely continue at least through
Wednesday evening.

&&

.MARINE...
Rough conditions out across the waters will continue into the
second half of the week as strong high pressure (1038 mb) remains
positioned to the north. Satellite data showed 25-35 kt winds
with seas hovering in the 12-15 ft range, which line up well with
buoy observations at the PacIOOS Mokapu station and a drifter
buoy east of Hilo this evening. Guidance supports this and
depicts a large belt of strong northeast to east trades over and
upstream of the state continuing. Gales will continue through
Thursday over the windier waters and channels of Maui County and
the Big Island. For the extended, a pattern transition is likely
late Friday through this weekend as a cold front approaches,
which means a break in the strong winds/seas.

Surf along east facing shores will remain rough, with heights
holding around the warning threshold of 15 ft (faces) through
midweek due to the aforementioned winds over and upstream of the
islands. A downward trend is expected late Thursday through the
weekend as the ridge weakens and winds ease.

Surf along north facing shores will remain well below the
seasonal average each day through early next week, with the
exception of the shores exposed to the large easterly seas. A
small west-northwest swell arriving Friday from a recent gale that
tracked eastward from the Kurils to the Date Line will linger
into the weekend. A small long-period pulse is possible Tuesday
out of the north-northeast from a gale predicted to move through
the Gulf of Alaska over the weekend. For the long-term (low
confidence), despite the differences shown in the various model
solutions, a more significant winter-like scenario unfolding will
become a possibility through the second half of next week in
response to broad low pressure evolving north-northwest of the
islands. Confidence through the extended portion of the forecast
should improve over the coming weekend.

Surf along south facing shores will remain near the seasonal
average each day, with mainly wind swell wrapping into exposed
areas.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM HST Wednesday for Kauai Leeward-Kauai
Mountains-Waianae Coast-Oahu North Shore-Olomana-Central Oahu-
Waianae Mountains-Lanai Mauka-Kahoolawe-Maui Windward West-Maui
Leeward West-Big Island Interior-Kauai North-Kauai East-Kauai
South-East Honolulu-Honolulu Metro-Ewa Plain-Koolau Windward-
Koolau Leeward-Molokai-Lanai Windward-Lanai Leeward-Lanai South-
Maui Central Valley North-Maui Central Valley South-Windward
Haleakala-Kipahulu-South Maui/Upcountry-South Haleakala-Big
Island South-Big Island Southeast.

High Surf Warning until 6 AM HST Thursday for Olomana-Maui
Windward West-Kauai East-Kauai South-East Honolulu-Koolau
Windward-Molokai Windward-Molokai Southeast-Windward Haleakala-
Kipahulu-South Haleakala-Big Island Southeast-Big Island East-
Big Island North.

High Wind Warning until 6 PM HST Wednesday for Kohala-Big Island
North.

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

Gale Warning until 6 PM HST Thursday for Maalaea Bay-Pailolo
Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island
Southeast Waters.

&&

DISCUSSION...Powell
AVIATION...Bohlin
MARINE...Gibbs