Small Craft Advisory 193, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
123 PM AKST Tue Nov 7 2017

.DISCUSSION...

Models...Not much change from yesterday as models remain in step
with good run to run continuity. Agreement remains good in the
short term. There is some disagreement in the midrange handling of
the low that will be moving across the Chukchi Sea Saturday. The
GFS want to make it a much stronger low and push int south of the
Brooks Range while the Canadian and ECMWF keep it north of the
Brooks Range. Location will have a significant impact on what will
happen in interior Alaska. Extended periods beyond 144 hours remain
in better agreement as ridge builds over the Bering Sea. The
07/12Z solutions initialized well against the 07/18Z surface
analysis with the front just a bit slower. Will utilize an equal
blend of solutions for most elements this forecast cycle, the
exception will be precipitation where we will use a bit more of
the NAM solution to bring snow into the Central Interior slightly
earlier than the other solutions are currently bringing it in.

Aloft...At 500 hpa...High amplitude ridge lies from a 556 dam
center over Yakutat over the AlCan Border and Beaufort Sea as it
continues east the slow march east. A 496 dam low that was over
the Sea of Ohkotsk has moved to 200 nm northwest of Wrangel
Island and will remain quasi stationary through Thursday morning,
then start moving east across the Arctic over 75N. A shortwave
associated with the low is moving over the northwest coast
extending south into the Middle Yukon Valley. The shortwave will
move northeast as it rides up over the ridging to the east. A
second shortwave is moving across the Gulf of Anadyr and the
central Bering Sea, and will move across the Chukchi Sea, Bering
Strait, and Eastern Bering Sea overnight, and by Wednesday morning
it will lie from Point Lay to Allakaket to Glennallen, and will
continue to move east in the zonal flow that develops over the
state. A third shortwave will move to the Chukchi Sea and central
Bering Sea Wednesday afternoon moving over the Northwest and West
Coasts Wednesday evening, moving east across the state south of
the Brooks Range on Thursday as a 512 dam low develops in the
Central Brooks Range. At 850 hpa...Some patches of above zero
temperatures hanging on over the eastern Arctic and Interior in
advance of the front, but the cooling trend has begun.
Temperatures will continue to fall the next few days to around
-10C, and to -10C to -20C by Friday morning. Expect a slight
 warmup on Saturday, then significant cooling starting Sunday.

Surface...High pressure hanging on in the Eastern Interior with a
1023 mb high in the Upper Yukon Flats and ridging extending
southwest to a 1019 high over Sleetmute, and southeast to a 1037
mb high in the southeast Yukon Territory. 965 mb low 300 nm
northwest of Wrangel Island will slowly weaken, then move east
along 75N as it continues to weaken, and by Friday morning it will
be 300 nm northeast of Wrangel Island at 992 mb. A weather front
associated with the low currently lies from Cape Halkett to Ruby
as it moves northeast riding up over the high pressure over the
Southeast Interior. The second front will move to the West Coast
tonight around midnight, and move east into the Western Interior
Wednesday morning spreading snow into the Central Interior in
advance of the front. The front will move northeast into the Yukon
Territory as the high pressure over the Yukon Territory recedes
southeast. A third front will move to the West Coast Wednesday
afternoon spreading significant snowfall to some West Coast and
Western Interior locations Wednesday night, before moving into the
Central and Eastern Interior on Thursday.

Arctic Coast and Brooks Range...Front is moving fairly rapidly
east across the area. Some lower clouds with the front and light
snow, but it has not lasted long in the areas it has passed
through and expect that to continue this evening before it falls
apart. Next front will spread snow over the Northwest Coast, then
it moves offshore, so maybe some flurries east of Wainwright on
the coast, but no significant snow. There will be some significant
snow in the Brooks Range Wednesday and Thursday and Winter Storm
Warnings have been issued and remain in effect. Winds gusting to
around 40 mph will kick up some blowing snow reducing visibility
at times to less than one half mile in the Brooks Range.

West Coast and Western Interior...Significant weather event
impacting the area will continue for the next few days. Strong
south winds will swing around to southwest and west behind the
next front that will be moving to the coast tonight producing at
least minor Coastal Flooding in Norton Sound Wednesday into
Thursday. The second front will be moving into the area overnight
and spread significant snowfall to portions of the Seward
Peninsula and Noatak Valley, areas of the Seward Peninsula, and
the Nulato Hills. See current Warnings and Advisories.

Central and Eastern Interior...Stratus cleared out finally, now
high clouds have moved over the area in advance of the front that
is riding northeast over the high pressure over the Southeast
Interior. As the next front approaches snow develops and pushes
into the Central Interior Wednesday morning and will continue on
and off through the day, then some clearing late Wednesday
evening before the next system moves into the area and spreads 2
to 5 inches of snow over the Central interior with 3 to 10 inches
of snow to the north of the Yukon River. Winds generally light and
variable. Temperatures cooling through the weekend.

&&

Coastal Hazard Potential Days 3 and 4...Models continue to show a
981 mb low moving across the Chukchi Sea Saturday and Sunday and
into northwest Alaska. This will bring strong west to northwest
winds of 25 to 40 mph gusting to 55 mph to the Chukchi Sea Coast,
and Kotzebue Sound. The strong winds will produce waves to 14 ft
in the Chuckchi Sea and 9 ft in outer Kotzebue Sound. There is
some ice in Kotzebue Sound, but expect that will not be enough to
provide any protection at this time. Confidence is increasing
that there will be at least minor Coastal Flooding in Kotzebue
Sound and around Shishmaref.

&&

Extended forecast for days 4 to 8...Confidence is increasing that
a significant winter storm will move into the state from the
northwest spreading heavy snow, gusty winds, and near blizzard
conditions in blowing snow to most of the forecast area Saturday
and Sunday. Snowfall will range from 4 to 12 inches, and winds
increase to 20 to 30 mph gusting to 45 mph. Behind the storm a
much cooler airmass will move over the state.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

High Wind Warning for AKZ213.

High Surf Advisory for AKZ201-AKZ202-AKZ207.

Coastal Flood Advisory for AKZ212-AKZ213-AKZ214.

Winter Weather Advisory for AKZ205-AKZ206-AKZ211-AKZ218.

Coastal Flood Warning for AKZ211.

Winter Storm Warning for AKZ208-AKZ210-AKZ212-AKZ217.

Heavy Freezing Spray Warning for PKZ230-PKZ235-PKZ240-PKZ245.

Gale Warning for PKZ200-PKZ210-PKZ220-PKZ225-PKZ230.

Small Craft Advisory for PKZ215-PKZ235.

&&

SDB NOV 17