Drought in Hawaii, April 1 to 30, 2017

Area Forecast Discussion
National Weather Service Honolulu HI
830 PM HST Fri Mar 31 2017

.SYNOPSIS...
A surface high far northeast of the islands will remain nearly
stationary through early next week, providing locally breezy trade
winds to the area. A front may pass north of the islands next
Wednesday, resulting in lighter trade winds for the area.

&&

.DISCUSSION...
Locally breezy trade winds continue across the islands this evening
as a surface high pressure remains far northeast of the area. Low
clouds embedded in the wind flow are reaching the islands at times,
bringing some showers to mainly windward and mountain areas. Latest
satellite imagery revealed patches of low clouds along the windward
coastal waters of Maui, Molokai and Oahu, while a bigger area of low
clouds just east-southeast of the Big Island will affect the
windward areas of that island later this evening into early morning.
Airmass in the island vicinity remains dry but slightly unstable, as
the afternoon Lihue and Hilo soundings indicated. Expect more
passing low clouds and showers to affect mainly windward and
mountain areas through rest of the evening into early Saturday
morning. Lee areas will see mainly fair weather, though lingering
clouds over the lee sections of the Big Island will keep skies a
little more cloudy there with even some showers possible.

The surface high pressure far northeast will hold and strengthen
slightly over the weekend. As such, locally breezy trade winds
across the islands will prevail and are expected to increase
slightly. Forecast models indicated an upper level ridge will remain
the island vicinity at the same time, with not much organized low
level moisture to reach the area. Therefore, expect trade wind
weather to prevail through the weekend, with passing low clouds and
showers to affect mainly windward and mountain areas. Lee areas of
the smaller islands will remain mostly dry, though Big Island lee
areas will see afternoon and evening clouds and possible showers.

The surface high far northeast is expected to weaken early next
week, as a low pressure system from the west advances east.
Furthermore, forecast solutions indicated a weakening cold front
associated the low pressure system may pass north of the islands
early part of next week. Looks like at least a surface ridge will
hold just north of the islands. Hence, this will result in the
trades easing a bit across the area early part of next week.
Forecast models do not indicate any significant increase in moisture
in the island vicinity, though a weak upper level trough may pass
the state, allowing airmass to become a little more unstable in the
island vicinity. All these still point to trade wind weather for the
islands early part of next week, though lighter winds can be
expected.

The trailing end of another front may reach the islands next
weekend, with a new strong high moving to far of the state behind
the front. stronger trade winds with an increase in clouds and
showers can be expected if this forecast scenario holds.

&&

.AVIATION...
Stable easterly trade winds will continue through the weekend with
the temperature inversion aloft ranging from 5000 to 8000 FT MSL.
Mostly VFR conditions are forecast with periodic MVFR ceilings in
showers at Hilo, and afternoon MVFR ceilings over Lanai. Brief
periods of MVFR ceilings and showers will also continue along
northern and eastern slopes of all islands.

AIRMET Tango has been issued for lower level mechanical
turbulence over mountains and southwest through northwest sections
of all islands. Wind speeds will increase slightly on Saturday,
expect low level turbulence to be a bit stronger and more
widespread this weekend.

&&

.MARINE...
A large west northwest swell continues to affect the islands this
evening, but appears to have peaked during the afternoon. A High
Surf Warning remains in effect for north and west facing shores of
most of the smaller islands, as well as for west-facing shores of
the Big Island, through Saturday. The swell will gradually ease
during the weekend. The high surf warning will likely be
downgraded to an advisory sometime on Saturday, and surf should
drop below advisory levels Saturday night.

The Friday morning ASCAT pass showed winds had reached Small
Craft Advisory (SCA) threshold in the Alenuihaha Channel, and
winds are likely at SCA levels across the other windier waters
around Maui and the Big Island as well. These winds, combined with
the large west northwest swell, require the Small Craft Advisory
to remain in effect for all Hawaiian coastal waters through
Saturday. This advisory is expected to be gradually scaled back in
areal coverage during the weekend as the swell subsides.

Surf along east-facing shores will build a bit while remaining
choppy during the weekend due to moderate to fresh trade winds.
This surf is then forecast to decline again early next week as the
trades weaken.

A slight increase in surf along south-facing shores is possible
through Saturday due to a long-period swell arriving from the
southern hemisphere. The west northwest swell will also wrap
around the islands enough to contribute to surf along some south
facing shores through Saturday. Surf along the south-facing
shores is forecast to decline again early next week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Warning until 600 PM HST Saturday for north and west
facing shores of Niihau, Kauai, Oahu and Molokai, north facing
shores of Maui and west facing shores of the Big Island.

Small Craft Advisory until 600 PM HST Saturday for all Hawaiian
waters.

&&

AVIATION...Bohlin
MARINE...Jacobson
REST...Hui