Wind Chill Advisory 33, NWS Fairbanks, AK

Northern Alaska Forecast Discussion...CORRECTED
National Weather Service Fairbanks AK
652 AM AKST Sat Feb 29 2020

.SYNOPSIS...
A strong low moving across the Bering Sea today will bring gusty
winds and snow with reduced visibility to the Y-K Delta and Lower
Yukon Valley tonight and Sunday, with snowfall amounts of 4 to 6
inches. Snow will spread from the southwest to the northeast
across the southern Interior through Monday. Snowfall totals of 6
to 12 inches are expected Saturday night through Sunday night for
zone 227. Further inland, along the southern slopes of the Alaska
Range, 6 to 12 inches of snow are expected Sunday through Monday.
Elsewhere in the southern Interior, snowfall amounts will
generally be 4 inches or less. Colder temperatures, with highs
near zero and lows in the 20s and 30s below, are expected to
return next Tuesday and to last most of next week.

&&

.DISCUSSION...
Aloft, at 500 mb, a broad trough centered in the high Arctic will
deepen and very slowly nudge eastward through the weekend and the
early portion of next week. A series of short waves will rotate
eastward through the flow. One short wave will move east over the
North Slope today, sweeping further south and eastward across much
of the state Sunday and Monday. A second short wave will push
across Wrangel Island and the Chukotsk Peninsula early Monday,
extending across the Chukchi Sea Coast and the western Brooks
Range to the Central Bering Sea by Monday evening, deepening as it
dives south across the state Tuesday. Another shortwave will move
northeast across the Aleutians this morning, across the Pribilofs
this afternoon, across Bristol Bay Saturday night and across the
Alaska Range Sunday.

Surface...A 998 mb low 500 nm N of Demarcation Point this morning
will weaken through the weekend as it moves very slowly eastward.
A weather front extending from this low southwest to the Chukchi
Sea will move east today pushing across the North Slope through
the day and past Demarcation Point by early Sunday morning.A 1016
mb high dives south this afternoon out of the high Arctic and
builds in quickly behind the front to be a 1014 mb high located
250 nm N of Utqiagvik by Sunday afternoon. The high will move east
Monday to be centered 200 nm north of Kaktovik Monday afternoon,
continuing eastward Tuesday.

A 972 mb low 100 nm southwest of Adak early this morning will move
northeast and deepen to be a 962 mb low 100 nm southwest of the
Pribilofs by this afternoon. As the low moves onshore,it will drag
a weather front with it, and the low weaken to be a 982 mb low
southeast of Aniak by Sunday afternoon, continuing eastward Sunday
night and Monday across the southeast Interior.

Models...
00Z model suite initialized well against the 00Z surface obs and
the 00Z RAOBS across much of Alaska and are in decent overall
agreement. 00Z NAM continues to show a deeper trough across
Alaska, bringing in lower heights than other model solutions.
There are some differences aloft with how fast the shortwave
moving out of the Bering tonight and tomorrow gets dampened out
and absorbed by the shortwave from the north, with the 00Z GFS and
the 00Z Canadian holding onto it the longest. Models come into
better agreement with heights of the second shortwave that moves
across the Chukchi Sea on Monday, but differences remain in the
timing of that feature.

At the surface, model solutions seem to struggle with the low that
moves across the Aleutians this morning and into the Bering Sea.
There is quite a bit of spread with the placement and the strength
of the low that moves across the Aleutians and into the Bering Sea
this morning. By 18Z today, there is an 8 mb spread in strength
and a 200 nm difference in location of the low in the solutions.
The Canadian is by far the strongest at 959 mb and furthest west
with the low, while the NAM at 966 mb is the furthest east. The
GFS and ECWMF fall in the middle and are similar in strength at
966 mb and 967 mb. As the low moves east of the Pribilofs and
across Goodnews Bay Saturday night and Sunday, model spread in
strength diminishes and solutions are grouped closer together.

Opted to go for a model blend for winds, with local edits for gap
winds in the passes of both the Brooks Range and the Alaska Range
and a weak Tanana Valley Jet. Made only minor adjustments to
timing of precip.

North Slope and Brooks Range: A weather front will push across the
Chukchi Sea today, brush the North Slope and move past Demarcation
Point by early Sunday morning. Flurries and light snow will
accompany the front. Snowfall accumulations less than half an
inch. Southwest winds of 10 to 15 mph will diminish this afternoon
becoming light tonight. As high pressure builds south towards the
coast, winds will shift around to the northeast and increase to
around 10 mph. Colder temperatures return Sunday.

West Coast and Western Interior: A strong low moving east across
the eastern Bering today and an accompanying weather front will
bring wind gusts to 40 mph, snow, and blowing snow to the Yukon
Delta and the Lower Yukon Valley tonight and Sunday. Snowfall
amounts will range from 2 to 4 inches across the Y-K Delta and 4
to 6 inches in the Lower Yukon Valley, with the highest amounts
south of a line from Russian Mission to Shageluk. Snow will spread
eastward Saturday night and Sunday, with 4 to 7 inches of snow
expected in the Middle Yukon Valley south of Galena and Ruby.
Winter Weather Advisories have been issued for zones 214, 215, and
216. Colder temperatures return Sunday night.

Central and Eastern Interior: Snow will spread from the southwest
across the southern Interior Saturday night and continue eastward
through Monday. Snowfall totals will range from 6 to 12 inches
through Monday for the south slopes of the Alaska Range, 4 to 6
inches south of Tanana, and generally 4 inches or less elsewhere.
Winter Weather Advisory was issued for zone 221 for areas south
of Tanana. Exact snowfall amounts for the Middle Tanana Valley are
a bit tricky. Southerly downsloping off the Alaska Range will
limit snow in the Fairbanks area initially. Total snowfall will be
highly dependent on how soon winds aloft shift to the southwest.
Have kept snowfall totals under 4 inches for the Middle Tanana
Valley for now. A weak Tanana Valley Jet of 15 to 25 mph with
gusts to 40 mph is expected to develop this morning and continue
through Sunday morning. Southerly gap winds are expected to
develop in the Alaska Range Passes with the strongest winds
occurring in the Eastern Alaska Range passes, where gusts to 60
mph will be possible this evening and tonight. A Winter Weather
Advisory was issued for the Eastern Alaska Range for the wind
gusts to 60 mph in passes which may reduce visibility in blowing
snow and for snowfall accumulations of 4 to 6 inches south of
Black Rapids. Temperatures warm Sunday before colder temperatures
return early next week.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory for AKZ209.

Winter Weather Advisory for AKZ214-AKZ215-AKZ216-AKZ221-AKZ226.

Gale Warning for PKZ210.

Brisk Wind Advisory for PKZ200-PKZ210-PKZ225-PKZ230.
&&

FEB 20