High Wind Warning 12, NWS Honolulu, HI

604 
WWHW70 PHFO 060150
NPWHFO

URGENT - WEATHER MESSAGE
National Weather Service Honolulu HI
350 PM HST Tue Dec 5 2017

...HIGH WIND WARNING HALEAKALA SUMMIT THROUGH 10 PM...
...WIND ADVISORY ELSEWHERE THROUGH 10 PM...

HIZ022-060800-
/O.CAN.PHFO.HW.W.0012.000000T0000Z-171206T0400Z/
/O.EXB.PHFO.WI.Y.0032.000000T0000Z-171206T0800Z/
Haleakala Summit-
350 PM HST Tue Dec 5 2017

...WIND ADVISORY IN EFFECT UNTIL 10 PM HST THIS EVENING...
...HIGH WIND WARNING IS CANCELLED...

The National Weather Service in Honolulu has issued a Wind
Advisory, which is in effect until 10 PM HST this evening. The
High Wind Warning has been cancelled.

* WINDS...North 30 to 45 mph with localized gusts over 60 mph are
  expected at the highest elevations.

* TIMING...through 10 pm HST this evening with winds diminishing
  quickly during the overnight hours.

* IMPACTS...Winds this strong can knock down tree branches and 
  lead to localized power outages. Motorists, especially those 
  in high profile vehicles, are urged to drive with extreme 
  caution.

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.

&&

$$

HIZ001>021-023>028-060800-
/O.EXT.PHFO.WI.Y.0032.000000T0000Z-171206T0800Z/
Niihau-Kauai Windward-Kauai Leeward-Kauai Mountains-
Oahu South Shore-Waianae Coast-Oahu North Shore-Oahu Koolau-
Olomana-Central Oahu-Waianae Mountains-Molokai Windward-
Molokai Leeward-Lanai Makai-Lanai Mauka-Kahoolawe-
Maui Windward West-Maui Leeward West-Maui Central Valley-
Windward Haleakala-Leeward Haleakala-Kona-South Big Island-
Big Island North and East-Kohala-Big Island Interior-
Big Island Summits-
350 PM HST Tue Dec 5 2017

...WIND ADVISORY NOW IN EFFECT UNTIL 10 PM HST THIS EVENING...

* WINDS...North to northeast 20 to 35 mph with localized gusts
  over 50 mph. 

* TIMING...through 10 pm HST this evening with winds diminishing
  quickly during the overnight hours. 

* IMPACTS...These stronger northerly winds may continue to affect
  parts of Hilo, Puna, and Kona which are typically sheltered from
  stronger winds during more usual trade wind directions. Winds 
  this strong can knock down tree branches and lead to localized 
  power outages. Motorists, especially those in high profile 
  vehicles, are urged to drive with extreme caution.

PRECAUTIONARY/PREPAREDNESS ACTIONS... A Wind Advisory means that
sustained winds of at least 30 mph, or gusts of at least 50 mph,
are expected.

&&

$$
R Ballard

Area Forecast Discussion
National Weather Service Honolulu HI
345 AM HST Tue Dec 5 2017

.SYNOPSIS...
Gusty north-northeast winds and very dry air will overspread the
state today as a cold front continues eastward across Maui County
and the Big Island this morning. A few showers along and ahead of
this boundary will be possible early, mainly over the northern
slopes of the Big Island and Maui. Dry and stable conditions are
expected Wednesday through Thursday as high pressure builds over the
area. Winds will quickly trend down and become light beginning
Wednesday. Weak frontal boundaries will approach and move through
the islands on Friday and Saturday resulting in an modest increase
in showers. Dry and stable conditions will return by Sunday. Another
front will be possible early next week.

&&

.DISCUSSION...
A pattern shift over the northern Pacific will result in more of a
progressive scenario across the islands through the upcoming
weekend. Recently animated water vapor loop showed northwest flow
aloft over the state between an upper ridge to the west and an upper
trough to the northeast, which should hold through the week. This
upper pattern will feature a series of shortwave troughs diving
southeastward across the region, pushing cold fronts toward and
through the area.

For today, gusty north-northeast winds and very dry air will
overspread the state as the first cold front in a series continues
eastward across Maui County and the Big Island this morning. Model
guidance indicates 850 mb winds climbing into the 40 to 50 mph
range. Surface winds will reach the 25 to 30 mph range for exposed
areas, with potentially stronger winds developing due to terrain
accelerations that occur with northerly flow. A Wind Advisory is in
effect for the state (except for Haleakala Summit and Big Island
Summits) through 6 pm today. This may need to be extended into
this evening for portions of Maui County and the Big Island.

Dry and stable conditions are expected Wednesday through Thursday as
high pressure noses over the area behind the front. Precipitable
water (PW) values are forecast to plummet to around half of an inch
(dewpoints dropping into the mid 50s). Winds will rapidly drop off
beginning tonight, likely giving way to land and sea breeze
conditions from Wednesday into Friday. The dry air, however, will
likely preclude any afternoon shower potential each day through this
time.

A weak cold front will drift southward onto Kauai and Oahu Friday
before dissipating, with a stronger cold front quickly following
behind it on Saturday. The fronts may bring an increase in clouds
and showers going into the upcoming weekend. Guidance indicates the
second front will usher in another shot of very dry air and gusty
northerly flow following its passage Saturday and Saturday night.
Winds are expected to rapidly drop off Sunday morning with another
ridge filling in behind. Another front may approach the state from
the north around Monday night or Tuesday next week.

&&

.AVIATION...
A shallow cold front currently crossing the state has brought a
modest uptick in showers. However, limited moisture depth and
instability has impeded shower intensity. The greatest chance for
MVFR conditions in showers will be over mauka areas, and across
north and windward facing sections. Otherwise, VFR will hold sway.

The more noticeable change following the front has been an increase
in wind speeds as a new high moves in northwest of the state.
Forecast soundings have shown winds as high as 35 knots below a
stable/very low inversion by later this morning. With this setup,
an AIRMET for moderate low-level turbulence to the lee of the
islands has been issued. With the next issuance at 0600 HST, the
AIRMET will include a remark to indicate the possibility of
isolated areas of severe turbulence as well. This will likely be a
short-lived event, with low-level winds starting to ease by
tonight.

&&

.MARINE...
Northeast winds will increase significantly today in response to
a cold front moving in from the northwest. Widespread Small Craft
Advisory (SCA) conditions are expected to hold into midweek, with
gale force conditions likely for the Alenuihaha Channel, Maalaea
Bay, and Maui leeward waters through this afternoon. This burst of
widespread strong winds will be short-lived, with winds dropping
below SCA levels Wednesday through the end of the week.

A new northwest swell has arrived and will continue to build
tonight. Buoy 51001 had a brief spike above guidance overnight,
but has been right on track for the most part. Models continue to
indicate surf rising through Wednesday as a large reinforcing
north-northwest swell fills in Tuesday. A High Surf Advisory
(HSA) is in effect for the north and west facing shores of Niihau,
Kauai, Oahu, and Molokai, as well as the north shore of Maui. The
HSA will likely be upgraded later today for warning level surf as
the reinforcing swell fills in tonight and Wednesday. This series
of swells will slowly trend down through the end of the week. The
forecast then calls for a very large north-northwest swell to
start building Saturday. This series of northwest swells will keep
most waters at or above SCA levels for combined seas through
Thursday.

Large surf associated with the aforementioned swells coinciding
with strong northerly winds, peak monthly tides, and beach erosion
from recent large surf events could translate to some overwash
onto vulnerable roadways through Wednesday. The best chance for
overwash will be centered around the pre-dawn high tide cycles
Wednesday.

East facing shores will be exposed to a short period north-
northeast swell that will bring advisory-level surf today, then
diminish through the rest of the week.

Small long period swells will keep surf above flat for the south
facing shores this week.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory through to 6 PM HST this evening for all areas
except for Haleakala Summit and Big Island summits.

High Surf Advisory until 6 PM HST this evening for north, west
and east facing shores of Niihau, Kauai, Oahu, Molokai, north and
east facing shores of Maui, and east facing shores of the Big
Island.

Gale Warning through 6 PM HST this evening for Maui County
Leeward Waters, Maalaea Bay and Alenuihaha Channel.

Small Craft Advisory until 6 PM HST Wednesday for all remaining
coastal waters.

&&

AVIATION...Kinel
MARINE...Stall
REST OF DISCUSSION...Gibbs