Drought in Hawaii, June 20 to 30, 2017

Area Forecast Discussion
National Weather Service Honolulu HI
900 PM HST Mon Jun 19 2017

.SYNOPSIS...
Locally gusty trade winds associated with high pressure northeast of
the state are expected to continue through Tuesday, before trending
down slightly Wednesday into the second half of the week.
Relatively dry and stable conditions will prevail, with showers
favoring windward and mauka areas through the overnight and early
morning hours each day.

&&

.DISCUSSION...
Relatively dry and stable conditions are expected to persist through
the week as a ridge of high pressure remains over the region.
Moderate to gusty trades south of this ridge will slightly trend
down temporarily through midweek as a weak front passes far north
of the state. The weak upper trough currently northwest of Kauai
is forecast to fill and lift northeast and away from the state
through this time, having little to no impact on the local
weather. Model soundings reflect this and exhibit a strong
subsidence inversion (near 6500 ft) with plenty of middle- to
upper-level dry air in place above it. Precipitable water values
are forecast to remain near or slightly below normal for this time
of year. This pattern will support a mostly dry forecast, with
showers favoring windward and mauka areas through the overnight
and early morning hours.

For the upcoming weekend, trade winds may become gusty once again as
high pressure builds north of the state behind the aforementioned
front passing far to the north. This increase combined with an upper
low approaching from the east could translate to better shower
coverage over the islands, mainly windward and mauka areas.

&&

.AVIATION...
Breezy northeast to east trade winds flowing over and around the
island terrain will continue to require AIRMET Tango for moderate
turbulence down wind of all islands. Otherwise expect passing
showers mainly over mountain areas and along north through east
slopes of all islands with isolated MVFR conditions.

&&

.MARINE...
The moderate to locally breezy trade winds will continue through
tomorrow before easing slightly on Wednesday. A Small Craft
Advisory (SCA) is posted for the typically windier waters around
the Big Island and Maui, including Maui County's windward waters
through Tuesday. A slight increase in trades will be possible
Friday into the upcoming weekend.

The long period 17 to 19 seconds south-southwest swell will
continue to fill in tonight and peak Tuesday night before
gradually subsiding into Thursday. A High Surf Advisory has been
posted for all south facing shores on all islands through
Wednesday afternoon. This swell will be reinforced by another
south swell of about equal size, arriving Thursday night, and
peaking on Friday. One difference with this swell, is that an
elevated astronomical King tide will be involved. The highest high
tide is set to occur Friday and Saturday afternoons, which could
translate to beach flooding and some street flooding in the
typical vulnerable locations. The high surf advisory is likely to
be extended through Friday in later packages.

The north and west facing shores are enjoying an off season
northwest swell. This swell of moderate size will gradually lower
through Thursday. A trade wind generated swell will provide small
to moderate size surf along the east facing shores.

The islands will also be affected by a southeast swell slated to
arrive Tuesday night and peak Wednesday. A very slow decline is
expected to follow, lasting into the weekend.

For more details, please refer to the Collaborative Surf Forecast
prepared by Pat Caldwell, under WMO header FXHW52 PHFO.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 4 pm Wed for south facing shores.

Small Craft Advisory until 6 PM HST Tuesday for Maalaea Bay-
Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big
Island Southeast Waters.

Small Craft Advisory until 6 AM HST Tuesday for Maui County
Windward Waters.

&&

DISCUSSION...Gibbs
AVIATION...Bohlin
MARINE...Lau