Wind Advisory 3, NWS Honolulu, HI

475 
WWHW70 PHFO 200150
NPWHFO

URGENT - WEATHER MESSAGE
National Weather Service Honolulu HI
350 PM HST Fri Jan 19 2018


HIZ026-200300-
/O.CAN.PHFO.WI.Y.0003.000000T0000Z-180120T0400Z/
Kohala-
350 PM HST Fri Jan 19 2018

...WIND ADVISORY IS CANCELLED...

The National Weather Service in Honolulu has cancelled the Wind
Advisory for the Kohala area of the Big Island.

Winds have subsided below the advisory threshold.

$$
Donaldson

Area Forecast Discussion
National Weather Service Honolulu HI
831 PM HST Thu Jan 18 2018

.SYNOPSIS...
A strong high pressure center located north-northeast of Oahu
this evening will continue to drift eastward away from the state.
Expect the windy weather across the Hawaiian Islands to continue
through the overnight hours. Wind speeds will weaken tomorrow
morning as the high moves far enough away from the state to allow
land and sea breezes to develop along southern and western slopes
of all islands from Saturday onward. Two bands of unstable clouds
are moving westward across each island tonight with enhanced cloud
ceilings and scattered shower activity mainly along windward
mountains and slopes. For next week, light east to southeast wind
directions will shift to southeasterly by Wednesday with southerly
flow possible by the end of the week as a cold front approaches
the islands from the northwest.

&&

.DISCUSSION...
Strong and gusty trade winds will continue through the overnight
hours as the strong high pressure center 800 to 1000 miles
north-northeast of Hawaii continues to move eastward away from
the state. A low pressure area with a cold front will move into
the Central Pacific helping to weaken the high pressure ridge axis
over the islands. This shifting large scale pressure pattern will
weaken the local pressure gradient over the Hawaiian Islands and
cause a decrease in wind speeds starting tomorrow morning.

A high wind warning remains in effect for the Kohala district of
the Big Island through the overnight hours with wind gusts greater
than 60 MPH reported by local observations. A wind advisory also
remains in effect for the rest of the state until tomorrow
morning. The Kohala district High Wind Warning will probably be
downgraded to wind advisory conditions by tomorrow morning. The
wind advisory elsewhere may need to be extended for some wind
favored locations as the wind speeds gradually recede. The evening
forecast continues to match current conditions with no evening
updates expected.

Saturday and Sunday...A decreasing wind trend will develop as the
high pressure ridge north of the islands weakens substantially. A
weakening cold frontal boundary will stall just 200 miles
northwest of Kauai as wind directions range from east to
southeast over the islands. Lighter east to southeast wind speeds
will allow on-shore sea breezes to develop along the western and
southern slopes of all islands by Saturday afternoon with off-
shore land breezes developing by Saturday night. Southeasterly
wind flow may aloft and weak sea breezes may keep shower activity
for most areas more isolated.

Monday and Tuesday...The ridge aloft remains weak with light
east to southeasterly winds. Meanwhile an upper level low shown
on the 500 mb chart is expected to drift into the Hawaiian
Islands. This low will set up around 300 miles northeast of the
islands likely enhancing upstream shower activity especially for
the northern islands of Kauai and Oahu. Forecast guidance on the
intensity of this upper level low between the European (ECMWF)
models showing a deeper system and the American (GFS) models
showing a weaker system are large enough to keep the chances for
precipitation impacts in the fair range at this point.

Wednesday through next Thursday...A deeper low pressure system
is forecast to sweep across the Central Pacific with a cold front
approaching the islands from the northwest. Wind directions will
veer towards the south by Thursday as pressure gradients shift
ahead of this next frontal system. Both global weather models are
in good agreement with this deeper solution and therefore we
should expect higher chances for showers along prefrontal
convergence bands in this developing weather pattern. Stay tuned.

&&

.AVIATION...
Strong trade winds are producing moderate to severe turbulence
near and downwind of island terrain, and thus AIRMET TANGO
continues. This AIRMET also includes strong surface winds across
all islands.

VFR conditions will prevail, however passing clouds and showers
will bring periods of MVFR conditions. No mountain obscuration is
anticipated, but a band of low clouds affecting windward sections
of the islands may cause problems later. Overnight observations
will be monitored for its possible occurrence.

&&

.MARINE...
A Gale Warning (GW) remains in effect this evening for the
typically windy waters sensitive to the trade winds. The GW is
good through 6am HST Friday morning, and this timing looks good at
this point as the trades are expected to begin weakening tonight.
The areas of the GW will ease to Small Craft Advisory (SCA) level
winds, and this SCA is slated to continue through Friday
afternoon. There is a good possibility that the SCA will be
extended through Friday night, and maybe Saturday, as described
below. The SCA cover the rest of the Hawaiian coastal waters, but
some zones will be canceled at 6 am HST Friday as the trades
soften.

A strong, broad surface high of 1037 mb is the system responsible
for the strong and blustery trade winds. This high, located some
850 nm NNE of the islands this evening, will continue to moving
east, further away from the islands. This will cause the trades
to soften, and veer toward the east and southeast over the weekend.

A High Surf Advisory (HSA) remains in effect for east facing
shores through tomorrow night, but may need to be extended into
weekend due to a large area of moderate to strong trades east of
the islands, despite the trades trending down locally. Surf
heights of around 8 feet will likely hold through Sunday for the
east facing shores. Further more, the SCA may be extended into
Sunday as well for waters exposed to this to the combination of
the winds and elevated seas associated with this easterly swell.

Surf will remain below advisory levels for the remaining shoreline
through this weekend. A small northwest swell (330 degrees) is
expected arrive Saturday night, and be reinforced with a moderate
west- northwest (300 degrees) swell on Sunday night through
Monday. The latter swell may warrant a HSA for the north facing
shores of some of the smaller islands.

&&

.HFO WATCHES/WARNINGS/ADVISORIES...
Wind Advisory until 6 AM HST Friday for Niihau-Kauai-Oahu-
Molokai-Lanai-Kahoolawe-Maui Windward West-Maui Leeward West-
Maui Central Valley-Windward Haleakala-Leeward Haleakala-Kona-
South Big Island-Big Island North and East-Big Island Interior.

High Surf Advisory until 6 PM HST Friday for Kauai Windward-Oahu
Koolau-Olomana-Molokai Windward-Maui Windward West-Windward
Haleakala-South Big Island-Big Island North and East.

High Wind Warning until 6 AM HST Friday for Kohala.

Gale Warning until 6 AM HST Friday for Maalaea Bay-Pailolo
Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island
Southeast Waters.

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

Small Craft Advisory until 6 AM HST Friday for Kauai Leeward
Waters-Oahu Leeward Waters-Maui County Leeward Waters.

&&

Discussion...Bohlin
Aviation...Powell
Marine...Lau