High Surf in Hawaii, March 25 to 27, 2018

Area Forecast Discussion
National Weather Service Honolulu HI
958 AM HST Sun Mar 25 2018

.SYNOPSIS...
Clear skies this morning over the western islands will become
cloudy with passing showers today as a upper trough sweeps by to
the north. Overcast high clouds over Maui and the Big Island will
push slowly east, with scattered showers expected this afternoon
and tonight. Southerly winds Monday will transition to light and
variable winds through midweek with afternoon showers expected.

&&

.DISCUSSION...
The tail end of a layered cloud band is moving slowly east over
Maui and the Big Island today with partial clearing expected over
those islands through the afternoon. Clear skies over the rest of
the state this morning will become increasingly cloudy today as a
transient upper trough pushes by to the north, bringing some
instability to the western islands of Kauai and Oahu. Expect
showers to form over the higher terrain this afternoon with
isolated downpours, and a slight chance of thunderstorms for
Kauai.

A surface low to the north with a trailing trough near Kauai will
bring increasing southerly flow over the rest of the state
tonight and Monday. Expect partly cloudy skies with scattered
showers Monday with additional terrain induced enhanced rainfall
along south facing slopes. The trough will pull north and east of
the islands Monday night and Tuesday leaving the state in a light
wind regime. The light winds will allow afternoon sea breezes to
form, along with nighttime downslope flow. The sea breezes and
island heating will bring afternoon clouds and convective showers
with clearing skies overnight. The weak trough will linger near
the eastern Big Island bringing some added shower activity along
the eastern slopes, mainly for the Kau and Puna Districts.

Trade winds will attempt a comeback Thursday and Friday with a
weak ridge trying to build northeast of the islands. Current model
predictions show light to moderate trades making it into the Big
Island and Maui County areas, but the sea/land breeze regime
holding on over Oahu and Kauai County. A cold front to the northwest
of Kauai looks to thwart the trade winds' eastward progress, and
may bring clouds and showers to the Garden Isle Friday and
Saturday.

&&

.AVIATION...
An upper level disturbance will move across the islands,
introducing a slight chance of thunderstorms over Kauai by this
afternoon and the waters north of Kauai and Oahu this evening and
tonight. The threat for thunderstorms will then move north of the
area late tonight.

At the surface, a low to the north of the area will keep the flow
around the state light into tomorrow. Expect afternoon sea
breezes and overnight land breezes at most terminals. The upper
level disturbance could help fuel periods of heavier showers over
the western islands this afternoon and evening and the eastern
islands tonight. Mountain obscurations may become necessary at
that time. Sea breezes will bring an increase in clouds and
showers over interior areas this afternoon, especially on Kauai
and Oahu where daytime heating will be the most prominent. Periods
of MVFR CIG/VIS could be possible.

A broken to overcast upper cloud deck over Molokai through Big
Island will slowly move to the east. AIRMET TANGO for tempo
moderate upper turbulence is posted over the eastern islands.

&&

.MARINE...
Winds and seas are expected to remain below Small Craft Advisory
levels for the next several days.

A transient upper trough will bring a slight chance of
thunderstorms to the northern waters of Kauai and Oahu through
tonight.

The current northeast swell will continue to slowly subside over
the next several days. A small short-period northwest swell is
expected to persist through Thursday, and small south and
southwest swells will continue over the next several days. Models
show a strong low developing off Japan and moving to the east
through much of the week. This could generate a northwest swell
that could bring advisory level surf to north and west facing
shores next weekend.

See the latest Oahu Surf Discussion (SRDHFO) for additional
details on surf and swell.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 PM HST Monday for Big Island Summits.

&&

Morrison...Discussion
Eaton...Aviation
MBallard...Marine