Area Forecast Discussion
Issued by NWS Honolulu, HI

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000
FXHW60 PHFO 200146
AFDHFO

Area Forecast Discussion
National Weather Service Honolulu HI
346 PM HST Sun Feb 19 2017

.SYNOPSIS...
Breezy to locally windy trade winds can be expected through the
middle of the week as high pressure builds in north of the state.
A few light showers can be expected over windward and mauka areas.
with most leeward locations remaining dry. Winds will drop off and
become more northerly later in the week as an area of low pressure
develops far north of the area.

&&

.DISCUSSION...
Clouds associated with a dissipating cold front presently lies
across The Big Island. A few light showers can be expected with
the front as is continues to move to the east southeast. A broad
swath of mid and high level clouds can be seen on satellite
imagery moving over the west end of the state with the thickest
cloud elements presently moving over Kauai and the adjacent
coastal waters. These clouds are expected to linger over portions
of the area through tonight before thinning out and moving away to
the east on Monday.

Breezy to locally windy trade winds will continue through
Wednesday with high pressure residing north of the area. The
airmass will remain rather dry and stable with precipitable water
values remaining below an inch. Shower activity will remain rather
limited with just brief passing light showers focused over
windward and mauka areas.

Later in the week an area of low pressure will develop far to the
north of the area. This will weaken the pressure gradient across
the area and turn our winds to a more northerly direction.
Generally dry weather will prevail for the most part with clouds
and a few showers continuing to fall primarily over windward and
mauka areas.

&&

.AVIATION...
High pressure building into the Hawaiian Islands from the
northwest will bring continued breezy to strong northeasterly
trade winds across the state through Monday evening. Expect
mostly VFR conditions after sunset with lingering low cloud
ceilings and showers over the windward slopes of the Big Island
until Monday morning. Moderate low level turbulence will continue
over southern and western sections of all islands.

AIRMET Sierra is in effect for mountain obscuration across
northern through eastern sections of the Big Island. The mountain
obscuration will likely continue tonight.

AIRMET Tango is in effect for moderate low level turbulence over
and downwind of all islands through Monday afternoon.

AIRMET Zulu is in effect for moderate icing over Oahu and Kauai in
layer 150-FL220. Icing conditions will likely end this evening.

&&

.MARINE...
Strong high pressure will continue to build north of the state in
the wake of a cold front currently moving over the Big Island.
This will maintain strong to gale-force winds over the waters
through Monday. Gales are expected across the Pailolo and
Alenuihaha Channels, as well as Maalaea Bay through Monday before
gradually trending down Tuesday through Wednesday. Local winds out
of the north this morning will veer to the northeast this
afternoon through Monday and more toward the east Tuesday. These
winds will generate very rough/short-period seas across the local
waters through the early part of this week.

In addition to the winds and rough seas, a large north-northwest
(330-350 deg) swell will peak this evening/overnight, then
gradually ease Monday through Tuesday. This swell is associated
with a storm-force low just under 1000 nautical miles north of the
state. Buoy 51101 observations (northwest of Kauai) peaked late
this morning and is currently on the downtrend, remaining in line
with the latest wave model guidance.

Surf along exposed north and west facing shores has responded
accordingly, nearing advisory levels this afternoon as the north-
northwest swell fills in. The surf is expected to peak this
evening and tonight, before trending down later Monday. It looks
unlikely that widespread advisory level surf will impact the north shores
of the Big Island with this event, given the large influence of
short-period wind waves, and only moderate period swell making its
way into those shores. Surf along east facing shores will
gradually rise through the week and near advisory levels Tuesday
through Wednesday as the winds veer out of the east.

On Wednesday, a moderate, long-period west-northwest (310 deg)
swell associated with a developing gale east of Japan is expected
to fill in, peaking late Wednesday through Wednesday night. This
swell will gradually ease Thursday, before a reinforcing swell
from the same direction, but longer period, builds in early Friday
morning. If this source comes in slightly higher than predicted,
advisory- level surf along north and west facing shores will
become a possibility beginning Wednesday and Wednesday night,
though an advisory looks more solid for the Friday time frame.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory until 6 PM HST Monday for Niihau-Kauai
Windward-Kauai Leeward-Oahu North Shore-Oahu Koolau-Molokai-Maui
Windward West-Maui Central Valley-Windward Haleakala.

Wind Advisory until 6 PM HST Monday for Lanai-Kahoolawe-Big
Island North and East-Kohala.

Small Craft Advisory until 6 PM HST Monday for Kauai Northwest
Waters-Kauai Windward Waters-Kauai Leeward Waters-Kauai Channel-
Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui
County Windward Waters-Maui County Leeward Waters-Big Island
Windward Waters-Big Island Leeward Waters-Big Island Southeast
Waters.

Gale Warning until 6 PM HST Monday for Maalaea Bay-Pailolo
Channel-Alenuihaha Channel.

&&

$$

Synopsis/Discussion...Burke
Aviation...Bohlin
Marine...Stall



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