Gale Warning 127, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
154 PM AKST Sun Nov 29 2020

.SYNOPSIS...
Light snow will develop over much of the region as an arctic
trough digs into the West Coast and a couple weak shortwave
troughs emanating from the Gulf lift north. The pattern amplifies
Tuesday and Wednesday as the West Coast arctic trough continues to
dig and a North Pacific storm moves into the Gulf, then across
the Alaska Range. Heavier snow will develop over the Western and
Central Interior with this system, with moderate chinook warming
over the Eastern Interior.

&&

.DISCUSSION...

Upper Levels and Analysis...
Broad upper level troughing encompasses the entire region as
numerous lows dominate the 3-D space. There is a clear and well
defined near 960 mb North Pacific low south of the ALeutian Chain
with another weakening low in the Gulf of Alaska, with that upper
level center around 499 dam. There is an arctic trough digging
south along the Northwest Arctic and Bering Strait. There is a
weak shortwave trough moving across the Copper Basin and Eastern
Alaska Range into the Interior. Overall, there is little change
from yesterday as the overall pressure gradient remains north-
northeasterly with the gradient pointing toward the Gulf of Alaska
and Bering Sea.

Model Discussion...
The numerical models continue to agree on the overall synoptic
pattern very well through midweek. However, they continue to have
subtle differences with how the West Coast upper trough merges and
phases with the North Pacific warm front moving into the Gulf of
Alaska on Monday and Tuesday. With that said, they models are in
better agreement than yesterday and there is high enough
confidence to continue with the "theme" of chinook warming over
the Eastern Interior and increasing snow threats over the
Western/Central Interior and North Slope. For this forecast a
blend of all the models was favored to average out the small
differences of the heaviest corridor of snowfall on day 2-3 with
the next storm. For the near term, a blend was also favored to
capture the broad scale light snowfall tonight and tomorrow. For
winds, the GFS/Canadian were favored to capture the stronger gales
over the North Bering Sea and Bering Strait.

Central and Eastern Interior...
Widespread light snow develops this evening and tonight, mainly
from the Tanana Valley north as a disturbance ejects the Alaska
Range and moves north to the Brooks Range by tomorrow. The system
exits early Monday with the next shot of snow developing late
Monday night and Tuesday as a strong Pacific warm front lifts
north of the AK Range and takes a similar track as the previous
system. Snow looks measly, and may even mix with some graupel or
sleet, as this front will have a very strong cross-barrier flow
behind it, so any precipitation will be short-lived until it
reaches the White Mountains and Yukon Flats. The front clears the
area on Tuesday afternoon, with moderate chinook warming becoming
the more interesting weather impact. Expecting temps to soar to
near freezing in the valleys and above freezing at higher
elevations given the strong warming aloft as 850 hpa temps reach
to 0 to 1 Celsius. Strong gap flows in the AK Range will likely
reach hurricane force with a strong easterly driven Tanana Valley
Jet (possibly going southerly at times at Delta Junction)
increasing Monday and lasting all the way through Wednesday.

West Coast and Western Interior...
Strong northerly winds to gale force and snow squalls will
continue for the next three days along the capes and across Saint
Lawrence Island. Light snow will develop over the Northwest
Arctic tonight, as well, as an arctic trough digs in. The next
system moves into the Western Interior on Monday afternoon with
snow increasing in intensity through Tuesday night as the front
stalls through Wednesday. This system still looks to bring several
inches of new snow accumulation to the Interior through Thursday.

North Slope and Brooks Range...
Light snow will move across the brooks Range into the Arctic
plain tonight, bringing light snow accumulations through Monday
before ending. A strong pressure gradient develops across the
coast Monday night and Tuesday, and this will bring increased
blowing and drifting snow, with the strongest winds over the
Eastern Arctic coast. It is possible for some significant areas
of reduced visibility over the Eastern Arctic, but this is
currently low confidence. Over the West Arctic, expect periods of
snow from Tuesday onwards as an arctic trough shifts east.

Extended Forecast Days 4-7...
On Thursday, the arctic trough will be shifting eastward with the
cold front moving across the Eastern Interior and North
Slope/Brooks Range, bringing increased snow chances. Colder arctic
air and mostly dry high pressure will settle in for the weekend
with temps falling back to normal after this warm spell. After
Sunday, uncertainty is high, but there will likely be a return to
snow threats as an arctic trough shifts west and allows for a
return of more Gulf of Alaska moisture inland.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

High Wind Watch for AKZ223-AKZ225-AKZ226.

Heavy Freezing Spray Warning for PKZ200-PKZ210-PKZ220-PKZ225-
PKZ230.

Small Craft Advisory for PKZ210-PKZ220.

&&

AHSENMACHER NOV 20

Special Weather Statement
National Weather Service Fairbanks AK
520 AM AKST Mon Nov 30 2020

AKZ213-010300-
St Lawrence Island and Bering Strait Coast-
Including Gambell, Savoonga, Brevig Mission, Teller, Wales,
and Diomede
520 AM AKST Mon Nov 30 2020

...Freezing Spray Possible at Savoonga through Wednesday...

Strong north winds of 25 to 40 mph are expected to persist in
Savoonga through Wednesday and temperatures are expected to fall
slowly as well. This will produce freezing spray that may impact
structures inland and accumulate on power lines.

For the latest forecast please visit weather.gov/fairbanks.

AKZ216-217-227-010300-
Lower Koyukuk and Middle Yukon Valleys-
Upper Kobuk and Noatak Valleys-Upper Kuskokwim Valley-
Including Galena, Nulato, Huslia, Kaltag, Ruby, Koyukuk, Ambler,
Shungnak, Kobuk, McGrath, Nikolai, Takotna, and Farewell Lake
520 AM AKST Mon Nov 30 2020

...Significant Snow for the Western Interior Tuesday and
Wednesday...

A front moving into the Interior will bring a round of snow over
the Western Interior beginning Tuesday afternoon and continuing
into Wednesday. Snowfall totals in the 6 to 12 inch range are
expected from Ambler south to McGrath.

For the latest forecast please visit weather.gov/fairbanks.