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Temp-1.3 C
RH16 %
WindENE 32 mph
RoadOpen (4x4)
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Hawaiian Islands Synoptic Discussion and Guidance

FXHW60 PHFO 160622

Area Forecast Discussion
National Weather Service Honolulu HI
822 PM HST Sun Jan 15 2017

A trade wind weather pattern will continue to build slowly across
the islands as the ridge of high pressure inches northward away
from the islands through Monday night. Generally dry conditions
can be expected over most areas over the next several days with
just a few passing showers expected, mainly over windward and
mauka areas. A windier and wetter trade wind weather pattern is
expected next weekend as a frontal band moves across the island


A ridge of high pressure sits about a hundred miles north of Kauai
this evening. It is close enough to maintain very light trades
across the western part of the island chain from about Oahu
westward, and a slight south of east wind flow across the windward
waters of the smaller islands. This ridge will stay put overnight
and into Monday thereby maintaining more of the same flavor through
Monday as it was today with daytime seabreezes taking over the
leeward beaches of these islands.

The ridge will start moving north Monday night allowing deeper and
stronger trades to spread westward to Kauai through Tuesday night.
Locally strong trades are already in place for waters south of the
Big Island and the Alenuihaha Channel which will continue for the
rest of the new week.

The second half of the week from Wednesday on will have moderate
to locally strong trades with a tad more trade showers for all of
the larger islands. The frequency of these showers will pick up
overnight then ease off in the morning becoming isolated by the
afternoons. A few of these showers will venture downwind into the
lee side of the smaller islands. All leeward areas will remain dry
including the Kona side of the Big Island.

A wetter trade wind regime is on tap for Saturday when a front is
expected to reach Kauai Saturday morning, then Oahu in the
afternoon, Maui County late in the afternoon or early evening,
and the Big Island late evening. The front will be ushering in
very breezy and gusty trades and showery weather that will linger
into the first couple of days of next week.


We expect predominantly VFR conditions at the terminals overnight
as cooling sets in and skies clear. MVFR conditions may occur in
scant showers across east and southeast sections of the Big
Island and Maui.

Continued sporadic reports of moderate turbulence just north of
our local waters, combined with the obvious digging of the
subtropical jetstream over the state, prompts us to continue
SIGMET tango for occasional moderate turbulence in the FL200/FL350
layer. This will persist through the night and into Monday.

Otherwise, no other AIRMETs are expected for the next few days.


The daytime ASCAT pass noted Small Craft Advisory (SCA) level
winds in the Alenuihaha Channel, so an SCA was issued for that
channel, and also waters south of the Big Island. We do not at
this time see an expansion of the SCA until or Tuesday when the
trades starts picking up.

A moderate west-northwest swell will continue into Tuesday, then
a large west-northwest swell is expected to arrive late Tuesday
night, peaking late Wednesday then returning to moderate levels
Thursday night. This swell will likely warrant a warning for the
north and west facing shores, and the lee shores of the Big
Island, due to its westerly component. Another large swell is
likely over the weekend, this time from a northerly direction.


Small Craft Advisory until 6 PM HST Tuesday for the Alenuihaha
Channel, waters south of the Big Island.




Bulletins, Forecasts and Observations are courtesy of Honolulu National Weather Service Forecast Office