High Surf Warning 5, NWS Honolulu, HI

Area Forecast Discussion
National Weather Service Honolulu HI
332 AM HST Wed Feb 14 2024

.SYNOPSIS...
Winds will strengthen out of the southwest today as a front
approaches from the northwest, then passes over the island chain
tonight through Friday morning. Expect increased clouds and
showers as the front passes by. North winds will fill in behind
the front, then become northeasterly trade winds through the
weekend.

&&

.DISCUSSION...
Troughing to our northwest has pushed a weakened subtropical
ridge across the islands this morning, keeping our winds light.
Cloud cover across the islands decreased from last evening, but
has begun to increase again early this morning across Kauai and
Oahu as light southwesterlies develop ahead of an approaching
front. Expect continued strengthening of these southwesterlies
statewide today. Rainfall was minimal overnight, reflecting a
rather dry and stable prefrontal airmass. Latest soundings showed
less than in inch of PW with positive lifted index values.

Models show the front approaching from the northwest will reach
Kauai tonight, then move down the island chain afterwards through
Friday morning. Expect a limited period of wet weather for each
island as frontal clouds and showers pass by. The front will have
little upper level support, so we are not expecting heavy rain or
thunderstorms along the boundary. High pressure will build in
behind the front, producing cooler temperatures along with breezy
north to northeast winds. Passing windward and mountain showers
will continue through early next week as the high shifts eastward
north of the main Hawaiian Islands this weekend.

&&

.AVIATION...
A cold front approaching the islands from the northwest will
produce southwesterly winds spreading across the state today. A
few showers will develop along south and west facing slopes of
each island today and tonight. This cold front will reach Kauai
later tonight and Oahu by early Thursday morning, producing
periods of MVFR conditions as the front marches eastward down the
island chain.

No AIRMETs are in effect and none are expected through this
afternoon. AIRMETs for mountain obscuration will be needed as the
front passes through each island.

&&

.MARINE...
An approaching cold front from the northwest will strengthen south
to southwest winds to more moderate magnitudes, with locally
stronger winds reaching Small Craft Advisory (SCA) thresholds
around Kauai, later today. The front will move down the state
from tonight through late Thursday as fresh northerly winds fill
in behind the front. Winds will gradually veer to the northeast
Friday and likely strengthen to SCA magnitudes as surface high
pressure moves into the central North Pacific. This high will pass
far north of the state on Sunday, maintaining fresh to locally
strong trade winds.

Surf along north and west-facing shores will remain small through
today with as background, short period northwest energy fades out.
A significant, XL northwest (320 degree) swell will arrive late
tonight and rapidly build down the island chain Thursday. This
swell will lift surf to well above High Surf Warning levels along
most north and west-facing shores. The passing of this swell
within moderate to locally strong northeast winds will result in
rough sea conditions and warrant an SCA for most local nearshore
waters. A swell of this size will adversely impact coastal areas,
especially during periods of high tide both Thursday and Friday
evenings. Preparations should be made for the threat of coastal
flooding as ocean water runs up and inundates beaches and
potentially affects coastal properties and roadways. The northwest
swell will slowly decline Friday and Saturday with a large,
medium period north swell (350 degree) following on its heels
Saturday and Sunday. This swell will maintain solid High Surf
Advisory level surf along most northern exposures and keep seas at
SCA heights. Surf along east-facing shores will experience a
rapid increase this weekend due to a combination of rough, short
period trade wind swell and large north swell. Seasonal small surf
will occur along south shores.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Warning from midnight tonight to 6 PM HST Friday for
Niihau-Kauai Leeward-Waianae Coast-Oahu North Shore-Maui
Windward West-Kauai North-Kauai East-Molokai Windward-Molokai
North-Molokai West-Maui Central Valley North-Windward Haleakala-
Big Island East-Big Island North.

Small Craft Advisory from midnight tonight to 6 AM HST Saturday
for all Hawaiian waters except Maalaea Bay-

&&

DISCUSSION...Powell
AVIATION...Bohlin
MARINE...Blood