Gale Warning 152, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
213 PM AKST Fri Dec 25 2020

.SYNOPSIS...
The area of most active weather this Christmas is over the Lower
Yukon Valley and the southwest Coast where a frontal boundary is
situated. This will continue to bring accumulating snow all the
way up along the Seward Peninsula through Saturday. Broad
southerly flow from the Gulf of Alaska is transporting quite a
bit of higher level clouds into the Interior, along with an
increasing pressure gradient across the Alaska Range. Otherwise,
weather is rather quiet this Christmas over much of the Mainland.
The most active weather heading into the weekend will remain out
west as a series of systems moves into the area as we head into
next week.

&&

.DISCUSSION...

Upper Levels and Analysis...
Broad upper troughing stretches from Eastern Siberia through the
Bering and into the North Pacific. A leading shortwave as the base
of this trough is moving north into the southwest part of Alaska,
with a large ridge over the eastern half of the Mainland. An
inverted surface trough stretches from Bristol Bay north into the
Lower Yukon and YK Delta with snow along the frontal zone. A large
cirrus cloud shield has moved into the Interior owing to a sharp
mountain wave across the Alaska Range. With the southerly warm air
advection pattern aloft, this has also allowed the gradient to
strengthen with gusty gap winds and a strong Tanana Valley Jet.

Central and Eastern Interior...
Strong warm air advection aloft has formed a very impressive
mountain wave and extensive upper level lee cirrus clouds. This is
resulting in a large shield of overcast skies over much of the
INterior, as well as a tightening lee trough pressure gradient and
Tanana Valley Jet. The gradient will remain in place as a series
of lows cross the AK Range, with the gap winds in the AK Range
becoming dominant by this weekend. Some gusty south winds in the
Brooks Range will be on/off as well at times with the southerly
flow aloft.

West Coast and Western Interior...
Snow is moving across the YK Delta, Lower Yukon, and Norton Sound
in association with an inverted surface trough/upper level warm
front. Snow will move offshore into Saint Lawrence Island tonight
before ending Saturday. Additional accumulations will be a few
inches or less after this afternoon. A powerful Bering front will
move into the YK Delta Sunday morning, bringing snow and blowing
snow to the region. Given the recent snowfall, and more snow
coming with the front, expect widespread blowing and drifting snow
across much of the West Coast. Most areas will see marginally poor
conditions, with the worst expected over the YK Delta and Bering
Coast given the east winds of 25-40 mph. This front continues
north and weakens on Sunday night with yet another low moving into
the SW coast on Monday.

North Slope and Brooks Range...
Quiet weather along the North Slope for now with periods of
stratus and fog. Flurries will also be possible at times with the
low stratus and light onshore flow from Utqiagvik east. The
gradient tightens along the West Arctic coast Saturday night and
Sunday, with snow moving in on Sunday and Monday as a front lifts
north of the Lisburne Peninsula. Expect some blowing and drifting
snow with this front.

Extended Forecast Days 4-7....
Beginning the extended period forecast on Monday evening, there
will be a series of troughs ejecting northwest across the West
Coast with continued ridging over the Interior. This will keep an
active weather pattern out west with warmer than average
conditions over the Interior along with continued southerly gap
winds over the AK Range. This general pattern looks to continue
through much of the coming week.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Wind Advisory for AKZ223.

Winter Weather Advisory for AKZ215.

Winter Storm Watch for AKZ211-AKZ213-AKZ214.

Heavy Freezing Spray Warning for PKZ210.

Small Craft Advisory for PKZ210.

Brisk Wind Advisory for PKZ200-PKZ220-PKZ225.

&&

AHSENMACHER DEC 20