Blizzard in Alaska, January 31, 2021

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
346 PM AKST Sat Jan 30 2021

.SYNOPSIS...
Light snow is expected tonight for the eastern Interior and the
eastern Arctic Coast. A cold airmass will start to push south into
the Interior tonight and will linger into Tuesday. Some locations
in the Interior may see their coldest temperatures of the season
over the next few days. With the cold airmass in place, very cold
wind chill values will be an issue at times beginning Sunday
night as easterly winds increase. Blizzard conditions are expected
for St. Lawrence Island beginning on Sunday.

&&

.DISCUSSION...
The 30/12Z model suite generally initialized well when compared with
observations. The models are in decent agreement with the synoptic
scale pattern out through early Monday. There is still some disagreement
between the models on how fast the Interior will clear out behind
the front. This introduces uncertainty into our temperature
forecast for the next 72 hours, especially for Fairbanks and
points to the east.

Aloft, at 500 mb, a 509 dam low is currently situated near
Utqiagvik, while a ridge is situated over the central Bering Sea.
The aforementioned low will dig to the south into the eastern
Interior over the next 48 hours, and will be over Northway by
Monday afternoon. As the low dives southward, H850 temperatures
over the eastern Interior will drop to around -30C by Sunday
afternoon. This low will continue to dive southeast Monday night.
Currently, the NAM and the ECMWF are quicker than the GFS at
moving the low and associated cold air southward. The flow aloft
will become more westerly by Tuesday night. Thereafter, the upper
level pattern looks to be much more progressive, but also more
uncertain.

Central and Eastern Interior...
Some light snow is expected for the eastern Interior as a front
pushes to the east. Most locations will see less than one inch of
snow as this system moves through, although some locations along
and north of the Yukon River may see up to two inches of snow.
Colder temperatures will start to push south over the area tonight
behind the front. How cold we get in the Interior will depend on
cloud cover, and right now, there are a lot of model differences
in how quickly the sky clears out behind the front. The central
Interior looks to clear out tonight, with slow clearing continuing
from west to east on Sunday. Valley locations in the central
Interior will see lows in the 30s below tonight after the skies
clear out. Sunday night much of the Interior will see lows fall
into the 30s below at valley level. Monday night, lows in the
eastern Interior will fall deep into the 30s below while the
central Interior will only fall into the 20s below. As easterly
winds pick up across the Interior we will see issues with very
cold wind chill values over summits and other channeled areas
beginning Sunday night and continuing into Tuesday night.

North Slope and Brooks Range...
Cold wind chill values are expected tonight into Sunday along the
eastern Arctic Coast and near Anaktuvuk Pass. We have Wind Chill
Advisories out through Sunday morning for these areas. The eastern
Arctic Coast and the eastern Brooks Range will also see some light
snowfall at times through Sunday afternoon. Less than one inch of
snow accumulation is expected. Low temperatures tonight along the
coast will be in the 20s below while the Arctic Plain will see
lows tonight approaching 30 below. Sunday night and Monday night
temperatures will approach 30 below along the coast with some
spots in the Arctic Plain seeing lows that approach 40 below.
Easterly winds will start to pick up along the coast Monday
resulting in wind chill values approaching 60 below by Monday
night along the coast.

West Coast and Western Interior...
Low temperatures tonight will dive into the 30s below across the
Western Interior while many spots in the Northwest Arctic will
see lows in the 20s below, with similar lows expected Sunday
night. Easterly winds will begin to increase on Sunday. With the
cold temperatures in place, advisory level wind chill values will
start to develop along the coast on Sunday, with advisory level
wind chill values developing in the Western Interior late Sunday
night. A front will bring snow to St. Lawrence Island Sunday into
early Monday. The snow when combined with winds gusting to 60 mph
will create blizzard conditions on St. Lawrence Island Sunday and
Sunday night. We upgraded the inherited Winter Storm Watch for
zone 213 to a Blizzard Warning. During the day on Tuesday, chances
for snow will increase along the west coast.

Extended Forecast Days 4-7...
Starting off the extended period on Tuesday night, we are going to
start to see a transition to a more active pattern for much of
the forecast area. We expect a transition to more westerly flow
aloft over the area. With this, we are looking at a system
bringing snowfall as it moves from west to east across the
forecast area Wednesday or Thursday, with the potential for
another system moving across during the weekend. The models all
hint at a transition to a more active pattern; however, they are
really all over the place in terms of timing of the systems. Stay
tuned for a potentially active week ahead.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory for AKZ203-AKZ204-AKZ206-AKZ207-AKZ209-
AKZ210-AKZ218.

Blizzard Warning for AKZ213.

Gale Warning for PKZ210.

Brisk Wind Advisory for PKZ200-PKZ220-PKZ225.
&&

JAN 21