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Area Forecast Discussion (AFD)

Issued by Fairbanks, AK (AFG)

                            
936 
FXAK69 PAFG 172357
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
257 PM AKST Sat Feb 17 2018

.DISCUSSION...
Multiple winter weather hazards along the West Coast and Western
Interior will be the main forecast concerns through the weekend 
into next week as a active, progressive pattern continues. A 
transition to a more active pattern is underway for the Eastern
and Central Interior as well as the North Slope over the next few
days. Model solutions are similar through Sunday afternoon with
differences between the deterministic model solutions from Sunday
night on and become more significant from Tuesday on with the 
strength and timing of individual shortwaves in the flow. 

Aloft...A long wave pattern consists of a deep trough over the Bering 
Sea and NW Pacific with a strong ridge over the eastern Pacific 
north over mainland Alaska. A series of strong short waves will 
move northeast through this pattern causing the ridge to weaken 
over time and the flow to become more zonal in the second half of 
next week. This will bring a series of strong storms across the 
West Coast and Western Interior, with the storms weakening as they
move over the Interior.

West Coast and Western Interior...It's going to be a bit of a mess
across the West Coast and Western Interior weather wise throughout
the forecast period. Several strong storms are progged to move
over the Bering Sea and Chukchi Sea and will bring strong winds,
blowing snow, heavy snow, and at some locations freezing rain.
Determining precipitation type and the potential for blizzard
conditions outside of current ongoing blizzard warnings was a bit
tricky. Temperatures will be in the upper 20s to mid 30s over
Norton Sound, Nulato Hills, and the Yukon Delta will make blizzard
conditions unfavorable, but may see reduced visibility to around
one half mile with new snow and strong winds. The potential for
freezing rain still looks likely for the Yukon Delta and the lower
and middle Yukon Valleys as well as the Upper Kuskokwim Valley
Sunday. Ice accumulations up to a tenth of inch for most
locations, except for up to two tenths in the Upper Kuskokwim
Valley. For the Winter Storm Watches that I inherited, I have 
opted to upgraded zone 209 to a Blizzard Warning, zones 208, 210, 
211, and 217 to Winter Storm Warnings for heavy snow and blowing 
snow, and zones 212 and 215 to Winter Weather Advisories for 
freezing rain and snow for this initial round of winter weather. A
second and stronger low will move into the Bering Sunday night 
and then north through Tuesday with another Wednesday and Thursday
will bring another round of heavy snow, blizzard conditions, and 
possibly freezing rain to the region. 

Eastern and Central Interior...A transition to a more active
pattern is underway. Several rounds of snow are expected from
Sunday evening through next week. The first round of snow will be
a quick, light shot, which will start Sunday evening for the
Central Interior then will spread east Sunday night into Monday
bringing 1 to 2 inches. The second round will come late Monday
night into Wednesday morning where there is the potential for
another 2 to 4 inches. A third, more significant snowfall event 
is offing for Thursday and Friday; however model details differ
over the timing and amount of precipitation to nail down exact
snowfall amounts. The potential for a snow/freezing rain mix or
freezing rain as precipitation develops Sunday night is looking 
less likely. Both the GFS and NAM forecast soundings show a decent
above freezing layer aloft Sunday morning and afternoon, but the 
overall profile cools to below freezing as the precip develops.
Otherwise, precipitation type will be snow through the multiple
rounds of precipitation this week. 

Arctic Coast and Brooks Range...Fairly quiet weather besides a 
few flurries are expected across the Arctic Coast through Monday 
before a more active pattern sets up. South to southeast winds 
will increase over the Western Brooks Range and western Arctic 
Coast tonight to between 20 to 30 kts, then extend east along the 
coast Sunday night and will be weaker between 10 and 20 kts. May 
see some blowing and drifting of snow, but not anticipating any 
visibility issues. The system moving up the West Coast Monday, 
will move into the western Arctic Ocean nu Tuesday morning, 
bringing strong winds, potential blizzard conditions, and snow to 
the area. Snow, strong winds, and potentially blizzard conditions
will develop Monday afternoon over the western Brooks Range and
western Arctic Coast...then progress east to the central Arctic
Coast Monday night and the Beaufort Sea Coast early Tuesday
morning. Will have to monitor for potential winter weather hazards
as models hone in on the details of this event.


Coastal Hazard Potential Days 3 and 4...Southwest winds 50 kt could 
push water and ice to near the runway at Gambell on Mon night and Tue.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning for AKZ208-AKZ210-AKZ211-AKZ214-AKZ217.

Blizzard Warning for AKZ207-AKZ209-AKZ213.

Winter Weather Advisory for AKZ212-AKZ215-AKZ216-AKZ227.

Gale Warning for PKZ210-PKZ220-PKZ225.

Brisk Wind Advisory for PKZ200-PKZ215-PKZ230.
&&

$$

LTH FEB 18