Brisk Wind Advisory 210, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
142 PM AKST Fri Dec 18 2020

.SYNOPSIS...
A high latitude blocking high over the Chukchi Sea with troughing
over the Bering Sea and Gulf of Alaska continues to dominate the
weather pattern over Northern Alaska. Cold arctic air continues
to spill into the Interior and across the North Slope with
blustery northeast winds and cold wind chills, however a pattern
change is on the way with clouds and light snow moving into the
southeast Interior tonight and continuing through the weekend.
Strong winds will develop through the Alaska Range on Monday and
continue into Tuesday. Much warmer temperatures will push into
the Interior Monday and Tuesday as a potentially significant
winter storm takes aim on the West Coast Monday and Tuesday.

&&

.DISCUSSION...

Upper Levels and Analysis...
The persistent 542 dam 500 hpa blocking high that has dominated
Northern Alaska weather for the past several days is beginning to
weaken and push to the west. The strong easterly gradient and
strong cold air advection into the interior is weakening and will
retreat to the North Slope through the Weekend as weak shortwaves
push into the Southeast Interior tonight through Sunday. Mostly
dry and cold conditions prevail over Northern Alaska, with the
exception of a few snow showers over the Bering Sea and St
Lawrence Island. A 488 dam 500 hpa trough pushes west over Western
Alaska and the Eastern Bering Sea as a strong upper level ridge
builds rapidly north and east over Eastern Alaska and the Yukon on
Monday. Strong southerly cross barrier flow develops over the
Alaska Range and will develop into a significant mountain wave
event bringing much warmer temperatures over Northern Alaska and
very strong winds in the and near the northern foothills of the
Alaksa Range. 850 mb temperatures will increase from around 20
below this afternoon to around zero to 2 above by Tuesday morning.
A potentially significant winter storm continues to be indicated
by model guidance to develop in the Southern Bering Sea on Monday.
A strong front rotating around the low will push into the Yk
Delta Monday afternoon and will continue to push up the coast
Tuesday. Heavy snow and strong winds are likely to accompany the
front. At this time winds are expected to remain off shore with
minimal coastal impacts as far as elevated water levels, erosion,
or ice pushes are expected along the West Coast.

Central and Eastern Interior...
Cold and blustery conditions continue through through this evening
but begin to improve later tonight as winds decrease and temperatures
increase with clouds and light snow moving into the Southern
Interior later this evening, however very cold temperatures in
the 30s to near 40 below are expected again tonight over the
Northern Interior before clouds move into the area by morning.
The first round of light snow moves into the ALCAN and Eastern AK
Range and west toward the Fortymile Uplands and into the White
Mountains this evening and tonight. Light snow is also possible
for the Tanana Valley, but it will be minimal if any snow actually
makes it through the very dry air in place. The next threat for
snow looks better for the Eastern Interior and possibly west into
the Central Interior, as well. This system will move in Saturday
afternoon through Sunday as it lifts northward, bringing light
snow accumulations. Temps drop again Sunday night as a quick shot
of arctic air moves through before a big ridge builds in aloft on
Monday, bringing a significant warm up on Tuesday. Very strong
winds are expected to develop in and near the northern foothills
of the Alaska Range on Monday afternoon and will continue into
Tuesday as a strong mountain wave sets up over the Alaska Range
Monday. Much warmer temperatures will push into the interior on
Monday and Tuesday with strong inversions likely in southern
Interior Valleys.

West Coast and Western Interior...
Strong and blustery easterly offshore winds continue to dominate
along the West Coast, keeping the whole region, including the
Interior, dry. A few flurries are falling over the Lower Yukon
associated with some low stratus, but this will not amount to
anything. Snow showers and blowing snow are also impacting Saint
Lawrence Island. Some light snow will be possible on Saturday as a
weak disturbance clips the Western Interior, otherwise, no major
weather impacts are anticipated beyond the current blustery wind
chills. Monday and Tuesday, a potentially significant winter
storm will move into the West Coast and possibly the Interior.
Details on the track and timing of this storm remain uncertain,
however at this time weather models continue to indicate the
potential for heavy snow and strong winds as a front rotating
around the low pushes up the coast on Monday. At this time winds
are expected to remain off shore with minimal coastal impacts as
far as elevated water levels, erosion, or ice pushes are expected
along the West Coast.

North Slope and Brooks Range...
Cold and blustery northeast winds continue with areas of blowing
and drifting snow. This same pattern continues into the weekend,
although it will wane over the Eastern Arctic Saturday as the
gradient relaxes there. Expect the worst blowing snow conditions
to remain over the West Coast over the next few days. The other
big story will be bitterly cold wind chills as a second surge of
arctic air moves in, bringing even colder temps and dangerously
cold wind chills.

Coastal Hazard Potential Days 3 and 4...
Computer models continue to indicate that a strong storm will
develop in the Southern Bering Sea on Monday. At this time the
forecasted track of the storm will produce mostly off shore winds
with minimal coastal impacts as far as elevated water levels,
erosion, or ice pushes expected along the West Coast with the this
storm.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory for AKZ220.

Winter Weather Advisory for AKZ201-AKZ203-AKZ219.

Heavy Freezing Spray Warning for PKZ210.

Gale Warning for PKZ225.

Brisk Wind Advisory for PKZ220-PKZ230.
&&

CCC DEC 20