Winter Weather Advisory 77, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
204 AM AKDT Sun Apr 11 2021

.SYNOPSIS...
A winter storm is moving northeast, with a second surge of
moisture moving into the YK and Saint Lawrence Island this
morning where blizzard conditions and significant blowing snow
continue. The storm will move inland, bringing heavy snow to the
Western Interior and into the Upper Koyukuk through Monday. The
Eastern Interior will remain dry and will see rapidly warming
temps as a strong chinook and high winds cross the AK Range.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a dynamic and strong 504 dam upper low over the Bering
Sea with a leading shortwave trough moving north toward Saint
Lawrence Island. There is another shortwave trough lifting north
from the NPAC bringing another surge of moisture laden air into
Bristol Bay. The cold and dry high pressure still dominates the
remainder of the Interior as ridging aloft builds in. 850 temps
over much of the southern Interior have warmed 10+ degrees C since
their min values from the last couple days, and this will continue
as south winds begin to rapidly increase over the AK Range.
Finally, the deep polar air mass and 493 dam upper low over the
Arctic remains, but is slowly beginning to depart to the northeast
as it retreats back to the Pole.

Central and Eastern Interior...
Warming temps will continue as the arctic high weakens and shifts
eastward, and moisture and clouds streams east from the West Coast
storm. An increasing cross-barrier chinook gap flow will build to
10+ mb by tonight, with hurricane force wind gusts from the south
in Isabel Pass. Also, expect potential for locally heavy snow and
drifting snow over the very southern part of Isabel Pass toward
Fielding Lake. Otherwise, this same pattern will also keep it dry
over much of the Interior, but snow will move into the Upper
Koyukuk and as far southeast as Tanana. The southern Brooks Range
will also see snow including the southern part of Atigun Pass this
afternoon through Monday. Expect some blowing and drifting over
the Dalton summits, as well, so travelers should prepare for
winter conditions. Temps will warm above average into the 40s
across the Tanana Valley Monday and Tuesday.

West Coast and Western Interior...
The winter storm for the West Coast continues to remain on track
as expected with ongoing blizzard conditions over Saint Lawrence
Island, and on/off blizzard conditions over the Yukon Delta this
morning. Strong easterly offshore winds will bring significant
blowing and drifting snow to the remainder of the West Coast today
and tonight, as well before tapering late Monday. Heavy snow
moves inland and north today and tonight, with little change in
expected accumulations as many Interior locales will see 4-7"
snow, with favored upslope areas seeing 8-12"+ through Monday
night. Snow showers will continue through Tuesday, with some brief
mixed rain/snow in the Lower Yukon and Delta today and tonight.

North Slope and Brooks Range...
Bitter cold temps will continue to warm as a front lifts north
across the Brooks Range this afternoon through Monday night. This
will also tighten up the easterly gradient along the coast with
blowing and drifting likely, especially over the Western Arctic.
South gradient will also build over the Eastern Brooks so expect
some falling snow and blowing snow through Atigun Pass, with south
winds into the 30 mph range. Snow showers continue over the
Brooks Range through Tuesday before tapering.

Extended Range Forecast Days 4-7...
Beginning the extended forecast on Wednesday, there is more
clarity than yesterday, now, as it seems a strong low will be
lifting north across the AK Range, which will bring another
chinook surge Wednesday and into Thursday, warming temps up over
all of the Interior and bringing another round of strong AK Range
gap winds. There may even be a very brief mix to rain over some
interior locales...

Otherwise, the flow looks to become zonal with much more
uncertainty by late week and weekend, with several waves of energy
crossing the North Slope, which may bring some winter weather
impacts up there. It looks drier and quieter for the West Coast
and Interior, however, with temps near normal or slightly above
for the weekend.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Wind Advisory for AKZ223-AKZ225.

High Wind Warning for AKZ226.

Winter Storm Warning for AKZ211-AKZ214-AKZ215-AKZ216-AKZ217.

Blizzard Warning for AKZ213.

Winter Weather Advisory for AKZ207-AKZ208-AKZ209-AKZ210-AKZ212-
AKZ219.

Gale Warning for PKZ215-PKZ220.

Storm Warning for PKZ210.

Brisk Wind Advisory for PKZ200-PKZ225-PKZ230.

&&

AHSENMACHER APR 21