Area Forecast Discussion
Issued by NWS Honolulu, HI

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FXHW60 PHFO 260201

Area Forecast Discussion
National Weather Service Honolulu HI
401 PM HST Tue Oct 25 2016

High pressure north of the state will maintain moderate trade
winds through Wednesday. The trades will strengthen Wednesday
night and Thursday, then remain strong through the weekend.
Showers will favor windward and mountain areas, with an increase
in showers expected late this week and into the weekend, as the
trade winds strengthen and a weak upper level trough develops over
the region.



High pressure far to the north is maintaining island trade winds
at moderate speeds with breezy conditions over the normally
windier areas. Dry conditions have prevailed today over most areas
with only a few weak showers over windward Kauai. Clouds and
limited showers will increase this evening over windward areas as
showers offshore push into the mountain slopes. Leeward areas can
expect a few isolated showers tonight and early Wednesday morning.

Showers will increase Wednesday in the late afternoon and evening
as a remnant frontal band passes from northeast to southwest
through the island chain. Rainfall totals will be light to
moderate as the cloud band pushes through. The leeward Big Island
will continue to see a diurnal pattern of increasing afternoon
clouds with scattered showers forming over the slopes.

The high pressure will maintain moderate trade winds through
Wednesday night. Trade winds will ramp up for the second half of
the week as the high pressure to the north strengthens and sinks
south. Expect a jump in wind speeds Thursday, with strong trade
winds continuing into next week as the high remains in place.

Upper level ridging will keep a cap on showers through Friday
afternoon with light to moderate rainfall amounts expected within
trade showers. An upper level trough is expected to push the ridge
south of the state Friday night and bring cooler temperatures
aloft over the islands. The cooler temps will increase instability
and allow for increased shower coverage and intensity Friday night
and into the weekend. With the strong trades and increasing cloud
growth, expect a wet trade wind regime over the weekend and into
next week.


High pressure to the north of the Hawaiian Islands will continue
to drive northeasterly trade winds through the TAF period. The
persistent trade winds along with a dry air mass crossing the area
will allow for mostly VFR conditions to prevail. The exception
will be with occasional isolated MVFR showers in windward and
mountain areas.

Moderate turbulence is expected just to the northeast of the
Hawaiian Islands and AIRMET TANGO may be needed tonight into early
on Wednesday as this area of turbulence nears Hawaii.


Moderate trade winds with locally breezy conditions will remain
through Wednesday before the trade winds ramp up once again. The
typically windier waters around the Big Island and Maui County
will see Small Craft Advisory conditions through this time before
spreading across all waters, likely by Thursday.

The current west-northwest swell has arrive larger than expected,
and is producing High Surf Advisory conditions on the north and
west shores of Kauai and the north shores of Oahu. A High Surf
Advisory is posted through noon Wednesday for these areas.
Blocking from the western islands and the west-northwest nature
of this swell will help keep surf below advisory conditions on the
west facing shores of Oahu and the north and west facing shores on
Molokai, Maui, and the Big Island. This swell is expected to begin
to lower by Wednesday afternoon. A series of smaller north-
northeast and northwest swells will then fill in through the
weekend, but surf is expected to remain well below advisory
levels. For the south facing shores a small long period swell will
bump surf up slightly Wednesday into Friday. A long period east
swell is possible this weekend from the distant Hurricane Seymour
in the Eastern Pacific.


High Surf Advisory until noon HST Wednesday for Niihau-Kauai
Windward-Kauai Leeward-Oahu North Shore-Oahu Koolau.

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



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