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Area forecast discussion 
National Weather Service Honolulu HI
330 am HST Sat Aug 23 2014

Synopsis...
high pressure north of the state will keep trade winds blowing
across the islands and local waters through the forecast period.
Clouds and showers will favor windward and Mauka areas. Winds will
become lighter this weekend and next week as high pressure to our
north weakens.

&&

Discussion...
a 1030 mb high near 42n145w...far north northeast of the main
Hawaiian islands...has an associated ridge extending southwest
through 30n170w and 26n180w. The pressure gradient between this
ridge and equatorial low pressure is sufficiently steep to keep 15
to 20 miles per hour northeast trade winds blowing across local waters this
morning. This represents a slight drop in wind speeds from last
evening. We have cancelled the Small Craft Advisory for waters
around Maui and The Big Island since wind speeds no longer satisfy
advisory criteria. Satellite loop shows loose patches of broken low
clouds are embedded within trade wind flow over and upwind from the
islands. One of these broken low cloud patches lies across windward
Big Island slopes and is poised to reach Maui within a few hours.
Radar shows scattered moderate showers within this cloud area...but
only isolated light showers farther to the west. We expect a
continued trade wind weather pattern for the forecast period...with
clouds and showers favoring windward and Mauka areas.

Models show the high to our north northeast will weaken and move
southwest by early next week. While the overall position of the
ridge will be unchanged...the weakened high will cause the pressure
gradient to slacken across the islands...resulting in decreased
trade winds. The current forecast keeps at least light trade flow
through the forecast period...but local land and sea breezes may
develop across leeward areas late next week and toward next weekend.

&&

Aviation...
showery low clouds embedded in the trade wind flow will bring brief
MVFR visible/ceiling to windward slopes...coasts and adjacent waters...otherwise
VFR conditions will prevail today. Some of the rain showers will
occasionally spread leeward on the smaller islands.

Low level winds are just strong enough to warrant a turb airmet for
the Lee areas early this morning...though the trend is for the winds
to lax a little therefore this airmet may not be needed later in the
day.

&&

Marine...
trade winds have decreased overnight...so the Small Craft Advisory
for the typically windier waters around Maui and The Big Island has
been cancelled. Winds are expected to continue to drop off over the
weekend and on into early next week.

The high surf advisory for south facing shores has been cancelled. A
series of moderate south swell are expected over the next several
days...with a slightly larger swell possible Wednesday and Thursday.
The combination of easterly trade winds and swell from distant
tropical cyclones will continue to produce moderate surf along east
facing shores through the middle of next week.

&&

Hfo watches/warnings/advisories...
none.

&&

$$

Synopsis/discussion/marine...Powell
aviation...hui

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