Drought in Hawaii, August 1 to 31, 2016

Area Forecast Discussion
National Weather Service Honolulu HI
913 PM HST SUN JUL 31 2016

.SYNOPSIS...
A broad surface high of 1033 mb is located 1700 miles north-
northeast of Oahu this evening. It has been supplying the islands
with trade winds the past few days, and will continue to do so for
much of this new work week. The trades are expects to strengthen
slightly during the next 24 to 36 hours to moderate to locally
strong. Then the trades turn lighter as we approach the upcoming
weekend. Showers embedded in the trades will favor the windward
and mountain areas, especially night and morning hours. The lee
side of the Big Island will see afternoon clouds and a few showers.

&&

.DISCUSSION...
It has been a rather wet evening from Oahu westward as several
areas of clouds and showers are moving through. These areas were
likely enhanced by a 700 mb trough oriented east to west across
the northern islands. Plumes of clouds and showers generated
by Molokai are also feeding into windward Oahu contributing to
the activity there. We continue to closely monitor this activity
over on windward Oahu. While it has been wet for the northern
islands, it has been relatively dry across most, if not all, of
the Big Island through this evening, perhaps due to a 700 mb ridge
that lies over the island.

So, with this trough as the culprit to the wet trades for the
northern islands...we do not see this pattern changing to a drier
regime until Wednesday as the trough fills. And for the Big
Island, the relatively dry pattern will return to normal
trade showers by Wednesday night. But by Wednesday night, we may
be getting the remnants of once tropical cyclone Georgette. It
will take about a day for the remnants to move through the state.
So it won't be until Thursday night or Friday when we have some
normalcy to the trade shower pattern. The remnants of Georgette
passing through the islands will maintain wet trade wind weather with
showers focused over the windward slopes. There are no upper level
troughs or lows to enhance these showers, so only moderate
rainfall totals are expected.

As for the strength of the trades, the surface high is forecast
to remain nearly stationary through the week, strengthening to
near 1038 mb by mid-week before weakening somewhat by the weekend.
With this said, we expect the current moderate trades to build up
slightly between Tuesday and Wednesday. The remnants of once
tropical cyclone Frank may nudge the trades up another notch as
it passes by to the south on Thursday.

The strength of the trades may diminish over the upcoming weekend
as the newly formed Tropical Depression Nine-E passes to the
north of the islands. Uncertainty is high at this time with this
scenario, so the forecast is subject to change. For more
information on Nine-E, see advisories issued by the National
Hurricane Center in Miami.

&&

.AVIATION...
AIRMET Sierra for mountain obscurations is in effect for windward
areas of Kauai and Oahu due to a band of clouds and showers
pushing across the western end of the state this evening. This
AIRMET will likely continue through tonight as the shower band
slowly moves west. Leeward sides of Kauai and Oahu will also see
occasional passing showers, brief MVFR ceilings and reduced visibility
at times. Conditions are expected to improve on Monday. No other
AIRMETS are in effect.

&&

.MARINE...
Winds and seas are expected to remain below small-craft-advisory
(SCA) levels through Monday. The high pressure system far to the
north-northeast of Oahu is forecast to strengthens in the next 24
to 36 hours resulting in locally strong trades that will warrant a
Small Craft Advisory (SCA) for the typically windier waters around
Maui and the Big Island. Another boost in the trades may come
Thursday.

Surf will be below advisory levels along all shorelines for the
foreseeable future. A series of small, long-period south to
southwest swells will provide small surf to south facing shores,
while trade winds supply short-period wind waves to east facing
coast.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
None.

&&

DISCUSSION/MARINE...Lau
AVIATION...Foster