High Surf Advisory 10, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
414 AM AKDT Fri Sep 29 2017

.DISCUSSION...
High surf on the western Arctic Coast, along with gusty winds and
snow north of the Brooks Range as well as the upper Kobuk and
Noatak Valleys are the main forecast concerns over Northern Alaska
through the weekend. The 00Z/29 deterministic model guidance is in
good agreement through the weekend with increasing spread in
solutions early next week. The exception is how the models are
currently handling an upper low and its surface reflection progged
to move north out of the northern Pacific Saturday night into
Sunday. There is are slight differences in the strength and track
of the low as it moves north over the Alaska Peninsula and
southwest Alaska Sunday and Monday.

Aloft...At 500 mb, a 508 dam low 215 nm north of Barrow with a
strong shortwave extending from the low over Kaktovik to Arctic
Village, then southeast over Stevens Village to Manley Hot Springs
and over the Upper Kuskokwim Valley. This shortwave will continue
to move southeast over the Middle Tanana Valley this morning and
over the southeastern Interior this evening. As the low moves east
over the Beaufort Sea today, another strong shortwave will dive
south over the North Slope this morning, reaching the Brooks Range
by early evening and then continue southeast over the Yukon Flats
and Fortymile Country tonight. A ridge of high pressure over the
Bering Sea and southwest Alaska coast will build east behind the
second shortwave over Northern Alaska with its axis over the
eastern Interior by early Sunday evening. A 550 dam low will move
north from the northern Pacific Sunday and will move north towards
to be over the Alaska Peninsula Monday morning with southerly
flow downstream over the Alaska Range and Interior Alaska. Cold
850 mb temperatures ranging from -5C to -12C stretching south over
the western Interior, Brooks Range, and North Slope will shift
east overnight tonight to be over the central and eastern Interior
Saturday morning. At least for the central and eastern Interior,
this will be the coldest H850 temperatures yet this season. H850
temperatures will gradually modify and warm through the weekend as
the upper level ridge builds east.

Surface...A 990 mb low 230 nm north of Barrow will move east over
the Beaufort Sea towards the Canadian Archipelago and be 400 nm
east of Banks Island by Saturday evening. Meanwhile, surface high
pressure will build northeast and over northern Alaska through the
weekend and over western Canada by late Sunday night. A southwest
to northeast oriented pressure gradient will tighten some through
late Saturday night over the Bering and Chukchi Sea. Leeside
troughing will develop north of the Alaska Range and over the
Tanana Valley Sunday evening into Monday morning. A 992 mb low
will move north out of the northern Pacific Sunday morning and
quickly move north over the Alaska Peninsula by Monday morning.

Arctic Coast and Brooks Range...High Surf Advisories remain in
effect for the western Arctic Coast through early this evening.
West to northwest winds sustained 15 to 30 mph with gusts up to 40
mph and seas 6 to 8 feet will persist through this afternoon and
will gradually decrease this evening as the low moves east.
Southwest to west winds will increase along the Beaufort Sea coast
and will be 25 to 35 mph by the evening. Several rounds of light
snow is expected for the area through Sunday morning. The first
round occurring now between Icy Cape and Cape Halkett will
continue through Saturday morning with the intensity peaking
between 18Z and 00Z today. Warm sea surface temperatures along the
coast will limit snowfall, but could see 1 to 3 inches through
Saturday morning. The second shot will move onshore this morning
west of Point Lay and will spread east over the western Brooks
Range through this afternoon, reaching the eastern Brooks Range by
evening. Could see 2 to 6 inches, heaviest west of the Dalton
Highway through Saturday morning. A third round will spread south
over the western Arctic coast Saturday afternoon, reaching the
Dalton Highway by Saturday evening. Snowfall amounts through Sunday
morning of 1 to 3 inches expected for the western Arctic Coast
and 2 to 6 inches over the coastal plains and Beaufort Sea coast
with the heaviest (possible 4 to 8 inches) east of the Dalton
Highway. Blowing and drifting snow will be limited due to the
relatively warm temperatures.

Eastern and Central Interior...A stalled front from near Eagle to
Fairbanks and Denali Park has brought up to three-quarters of an
inch of rainfall to the area over the last 24 hours. The back
edge of the precipitation currently sits north of Eagle to Circle
through Fairbanks to Lake Minchumina this morning and will
continue to shift southeast over the eastern Interior through the evening.
Snow levels have decreased overnight to between 1000 to 1500 feet
this morning across the area with snow mixing in with rain below
1000 feet. A shortwave will move over the area tonight into
Saturday morning and will bring a chance of light snow to the
eastern Interior. Snowfall accumulations will be negligible, a
dusting at best at higher elevations. Temperatures will continue
to cool through Saturday with overnight lows Saturday morning in
the mid teens to 20s. Temperatures will then rebound through the
rest of the weekend to slightly above normal values.

Western Interior and West Coast...Snow will spread over the lower
Noatak and Kobuk Valleys this morning and then over the upper
Noatak and Kobuk Valleys by this evening. Snow levels at the
surface will increase across the area to around 1500 feet by this
afternoon and above 3000 feet by Saturday morning. rain will mix
with snow initially, but will transition to all rain below 3000
feet by Saturday morning. Above 3000 feet, snowfall accumulations
of 3 to 6 inches is possible through Saturday morning. Southwest
to west winds will increase to 20 to 30 mph over the Bering Sea
north over the Bering Strait and Chukchi Sea Saturday night into
Sunday.

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

&&

.HYDROLOGY...None.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory for AKZ201-AKZ202.

Small Craft Advisory for PKZ210-PKZ215-PKZ240-PKZ245.

Gale Warning for PKZ230-PKZ235.
&&

LTH SEP 17