High Wind in Alaska, October 4 to 5, 2017

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
224 PM AKDT Tue Oct 3 2017

.DISCUSSION...
Main forecast concerns include any impacts associated with the
Bering Sea storm advertised to impact southwest Alaska mid to late
this week and the potential for strong winds through Alaska Range
passes late Wednesday into Thursday morning. The 03/12Z
deterministic model suite is in good agreement through 78 hours (18Z
Friday) with increasing spread in model solutions after 78 hours.
There is now general model consensus in regards to the track of
the strong Bering Sea storm advertised to impact southwest mid to
late this week. However, there are some differences with the
strength of this low as it approaches with the GFS and CanadianNH
being the strongest around 960 to 965 mb, and the ECMWF and NAM
weaker around 970 to 975 mb.

Above normal temperatures will persist across Northern Alaska
through Thursday with a cooling trend towards near normal
values Friday into the weekend.

Aloft...At 500 mb, a long wave ridge over eastern Alaska and
western Canada will persist through Wednesday, then will be pushed
east into western Canada. A long wave trough persists across the
Bering Sea and far western Alaska and will shift to encompass all
of mainland Alaska. A 525 dam low over the southern Kamchatka
Peninsula will move out into the Bering Sea and deepen through
Wednesday. By late Thursday afternoon, this will be 350 nm
southwest of Saint Lawrence Island at 507 dam. This strong will
low will continue to move east and make landfall over Cape
Romanzoff/Hooper Bay by 18Z Thursday, then move inland over
western Alaska Thursday into Thursday night. Models are hinting
that an upper level ridge may build north over the Gulf of Alaska
and southern Alaska late this weekend.

Surface...A 1003 mb low over Norton Sound will move north and into
the Chukchi Sea tonight. A strong low will develop over the
western Bering Sea Tuesday night into Wednesday morning and will
move east across the Bering Sea making landfall at around 970 mb
near Cape Romanzoff/Hooper Bay by 18Z Thursday. This low will then
move inland and weaken Thursday night and be around 990 mb 12Z
Friday over the lower Yukon Valley.

West Coast and Western Interior...General model consensus tracks
the strong Bering Sea storm onshore near or at Cape Romanzoff
Thursday morning. The advertised track of this low will keep the
strong westerly winds and high storm surge values well south of
Cape Romanzoff. The main impact to the Yukon Delta, Norton Sound,
and the northern Bering Sea will be strong south to east winds on
the north side of this low. Storm surge values in the vicinity of
the low for Scammon Bay will be 1 to 3 feet, which is within the
normal range. The main impact will be strong winds, where there is
the potential for south to east winds sustained 40 to 50 mph with
gusts to 60 mph are possible Wednesday afternoon through late
Wednesday evening for the Yukon Delta Coast and Saint Lawrence
Island. Inland, over the lower Yukon Valley, sustained winds of 30
to 40 mph with gusts to 50 mph are possible. This looks to be a
short-duration high wind event, lasting around 12 hours as the
front associated with the low moves onshore. A high wind watch
has been issued for zones 213, 214, and 215 for the potential for
strong winds meeting high wind warning criteria. Otherwise, the
weather pattern will remain unsettled with chances for
precipitation continuing through the rest of the week.

Eastern and Central Interior...The main forecast concern will be
the potential for strong winds through Alaska Range passes
Wednesday night into Thursday morning. This looks to be a short-
duration event and not as strong as the recent Chinook event.
Looks like the south winds will increase through the evening
tomorrow, peaking between 05/09Z and 05/15Z before decreasing
through the morning Thursday. Have issued a high wind watch for
the potential for sustained winds 40 to 50 with gusts up to 60
mph. Chances for rain across the central Interior tonight and for
the far eastern Interior Wednesday afternoon and evening.

Arctic Coast and Brooks Range...NAM and GFS BUFR soundings show
the potential for a brief period of freezing rain between Icy Cape
and Nuiqsut between 12Z to 18Z tonight. The best chance however
will be between Icy Cape and Barrow, where a northward moving
shortwave will bring a round of precipitation to the western
Arctic Coast and Brooks Range tonight into Wednesday morning. Over
the western Brooks Range, snow is likely where 1 to 3 inches are
possible above 4000 feet through Wednesday morning. Chances of
snow will spread east over the Brooks Range and eastern North
Slope Wednesday, where snowfall accumulations of 2 to 4 inches
are possible through Thursday morning. Areas of fog with
visibility under one mile and low ceilings in stratus will persist
along the coast east of Barrow tonight.

Coastal Hazard Potential Days 3 and 4...None.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Wind Watch for AKZ213-AKZ214-AKZ215-AKZ225-AKZ226.

Small Craft Advisory for PKZ200-PKZ235-PKZ240.

Gale Warning for PKZ210-PKZ245.
&&

LTH OCT 17