High Wind Warning 5, NWS Honolulu, HI

742 
WWHW70 PHFO 110135
NPWHFO

URGENT - WEATHER MESSAGE
National Weather Service Honolulu HI
335 PM HST Sat Feb 10 2018

HIZ028-111445-
/O.CAN.PHFO.HW.W.0005.000000T0000Z-180211T1600Z/
/O.NEW.PHFO.WI.Y.0010.180211T0135Z-180211T1600Z/
Big Island Summits-
335 PM HST Sat Feb 10 2018

...WIND ADVISORY IN EFFECT UNTIL 6 AM HST SUNDAY...

The National Weather Service in Honolulu has issued a Wind
Advisory, which is in effect until 6 AM HST Sunday. This replace
the High Wind Warning that had been in effect for the Big Island
Summits.

* WINDS...North 25 to 50 mph with localized gusts over 60 mph are
  expected over the Big Island Summits.

* TIMING...through 6 am Sunday.

* IMPACTS...Winds this strong can make driving and walking 
  difficult and can forcefully slam open doors.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Advisory for the summits means that sustained winds of at
least 45 mph, or gusts of at least 55 mph, are expected. Motorists
should use extra caution.

&&

$$

Area Forecast Discussion
National Weather Service Honolulu HI
321 AM HST Sat Feb 10 2018

.SYNOPSIS...
Dry and pleasant conditions will continue through the weekend.
Breezy northerly winds will gradually shift out of the northeast and
weaken tonight through Sunday as low pressure east of the state
drifts into the area as a weak trough. A slight increase in moisture
associated with this weak trough may translate to better windward
shower coverage tonight through Sunday. Moisture and rain chances
will rise early next week as a cold front and upper trough approach
and move into the area.

&&

.DISCUSSION...
Water vapor loop showed the islands centered between a broad upper
low a few hundred miles to the east-northeast and an upper ridge
oriented from northeast to southwest a few hundred miles to the
west. North-northwest winds aloft and dry middle- to upper-level air
between these two upper features were shown over the state, which
are translating to more of a suppressed environment. At the
surface, breezy northerly winds and dry conditions continue, which
should hold through the day today. Dewpoints are forecast to
remain in the 50s with precipitable water (PW) values remaining
around an inch or less (dry). A combination of the dry air and
subsidence aloft will limit rainfall chances over the islands
today.

For the Big Island summits, winds have steadily dropped through the
overnight hours, but remain around advisory levels as of this
discussion time. As a result, a wind advisory is now in effect
for the summits through noon, which replaces the warning
previously in effect. The strong winds will gradually trend down
later today through the rest of the weekend as the upper ridge to
the west builds eastward over the islands.

Short-term model guidance remains in good agreement tonight through
Sunday night and shows the gradient over the islands weakening as
low pressure drifts westward into the area as a weak trough. The
gusty northerly winds will trend down and become light beginning
tonight, potentially giving way to land and sea breeze conditions
over some areas Sunday and Sunday night. A slight increase in
moisture associated with this trough combined with a light
background easterly low-level flow may support better windward
shower coverage by Sunday as the airmass continues to modify.
Model PWs support this and depict a modest increase with values
trending up to around 1.25". Dewpoints are forecast to climb back
into the 60s Sunday.

Despite the increasing forecast uncertainty early next week due to
model differences and changes from cycle to cycle over the past
couple of days, increasing moisture and rain chances appear likely.
The GFS, GFS ensemble mean, and ECMWF all depict a cold front and
sharp upper height falls associated with an upper trough moving into
the area Monday through midweek. Cold temperatures aloft along
with increasing moisture may translate to increasing chances for a
wintery mix on the summits by midweek as well. Additional fine
tuning of the forecast will be likely over the weekend as
confidence steadily rises and better agreement is shown between
the various model solutions.

&&

.AVIATION...
AIRMET Tango will remain in effect today for moderate turbulence
south of the main Hawaiian islands due to strong north winds. No
other AIRMETs are anticipated today. VFR conditions will prevail,
but there may be periods of MVFR ceilings along north slopes as
stable low clouds move over the islands.

&&

.MARINE...
Winds and seas have begun to drop across the western portion of
the main Hawaiian islands, allowing for cancellation of the Small
Craft Advisory (SCA) for waters west of Oahu. The SCA remains in
effect for remaining waters through this afternoon. Winds and
seas will continue to decrease into early next week.

A northwest swell will continue to lower gradually through
tonight. However, a moderate sized northwest swell is expected to
fill in tonight and Sunday. A slightly larger reinforcing
northwest swell is expected on Monday with a second reinforcement
expected Tuesday into Wednesday.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until noon HST today for Big Island Summits.

Small Craft Advisory until 6 PM HST this evening for Oahu
Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County
Windward Waters-Maui County Leeward Waters-Maalaea Bay-Pailolo
Channel-Alenuihaha Channel-Big Island Windward Waters-Big Island
Leeward Waters-Big Island Southeast Waters.

&&

AVIATION...Donaldson
MARINE...Powell
REST OF DISCUSSION...Gibbs