Winter Storm Watch 21, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
653 AM AKDT Sun Mar 24 2024

.SYNOPSIS...
A southerly flow pattern over Alaska will persist the first half
of this week. This will keep the Eastern Interior and Eastern
North Slope much warmer than normal and dry into Mon. The Western
Interior will remain warmer than normal with periods of rain,
snow, and possibly freezing rain. The West Coast and Western North
Slope will be slightly warmer than normal today. Snow and
blizzard conditions over the Yukon Delta and SW Interior will
spread north to Point Hope and the Western North Slope late today,
and then continue into Mon. The southwest Interior will change
over to rain this afternoon, with areas south of the Seward Pen
will change over to rain on Mon. These areas could see freezing
rain today into tonight.

Southerly chinook winds of 50 mph blowing through AK Range Passe
will decrease this afternoon.

Warmer than normal temperatures will continue through the middle
of next week, with the West Coast remaining wet and the Eastern
Interior remaining dry. Conditions most areas will cool back to
near normal next weekend.

Surface...
An Arctic front stretching from Inuvik to Kotzebue to the YK Delta
will persist today, then move to Barter Island to White Mountain
to the YK Delta by 4am Mon, then to Old Crow to Nome to the YK
Delta by 4pm Mon, then remain in place. Precip will be mainly snow
northeast of the Arctic front, with mixed snow, rain and freezing
rain along the front and mainly rain and snow south of the front.

A strong low in the southeast Bering Sea will move to Bristol Bay
by 4am Mon and then weaken slowly. A polar occluded/warm front
stretching form this low to the YK Delta to Unalakleet to Eagle
will over run the Arctic front and move aloft to the YK Delta to
Kotzebue to Barter Island by 4pm today, then remain in place
through 4am Mon with a 996 mb low developing near Barter Island.
On Mon the front will weaken in place with the low moving to 100
NM northeast of Barter Island a 997 mb low, then the low will move
to 150 NM northeast of Barter Island as a 997 mb low by 4am Tue.
A 987 mb low developing over the Yukon Delta by 4am Mon will move
to 300 NM south of Gambell as a 992 MB low by 4am Tue.

The northward moving occluded front will cause north winds to
increase along the West Coast today, and over the Western Arctic
Coast tonight. Snow will spreads north with this front today and
tonight then taper off Mon as the front weakens.

&&

.DISCUSSION...
Models Initialize well aloft at 00Z and show similar solutions
aloft through 4pm Tue. Models show similar long wave pattern after
that, but show increasing differences in short wave details in
the second half of the week. Will use a blend of models for
features aloft through Tue.

The long wave pattern consists of a strong ridge over the Eastern
Pacific north over NW Canada and Eastern Alaska and a deep long
wave trough over the Bering Sea and NW Pacific. This long wave
pattern will persist through late this week, then become
progressive with the trough moving east over AK next weekend.
This is causing a southerly flow pattern over Alaska that is
causing weak to moderate chinook conditions over the Southeast
Interior, and pushing warm air north across most of Northern
Alaska. A series of short wave troughs moving north over Alaska
will bring periods of snow and even rain north over the West
Coast and Western Interior through Mon, with snow spreading into
the Western North Slope later today, and then to the Eastern North
Slope Mon night and Tue.

With precipitation, models show similar general patterns for areal
coverage today, then the ECMWF pushes precip further to the NW
tonight and Mon than the NAM and GFS. Given that there is an
Arctic front over Western AK that is being over run by warm moist
air associated with a polar warm front and that there is moderate
SE flow aloft, favor the precip pushing further NW over all of NW
AK as shown by the ECMWF. Models come back into fair agreement on
precip areal coverage Mon PM into Tue PM. Precip occuring along
the West Coast from the Seward Pen south, and over SW Interior
will spread north to Point Hope, Anaktuvuk Pass, Deadhorse and
Utqiagvik by 6pm today, with precip continuing over the West
Coast, Western and Central North Slope, and the far western
Interior into Mon. Precip will taper off over NW AK Mon night and
Tue while it spreads to NE AK Mon night and Tue. The SE Interior
remains dry through Tue due to chinook flow across the AK Range.
Expect precip to be mixed rain and snow SE of Huslia to Elim to
the YK Delta, with freezing rain possible through Mon. NE of
Huslia Elim and the YK Delta precip with by mainly snow with
possible freezing rain rain through Mon. Expect several inches of
snow most of the West Coast and North Slope through Mon night,
with 4-6 inches over the Western Seward Pen and St Lawrence Is.
Any ice accumulations will be just a trace.

At the surface at 06Z, models all verify 2 mb too weak on the low
near Cold Bay and 4-5 mb too weak on the low in the Southeast
Beaufort Sea. Since the Beaufort Sea low is moving east today
this will make little difference. The Cold Bay low will likely
remain several MB deeper than models indicate through tonight, and
this will result in wind being several KT stronger along the West
Coast through tonight. Models show similar solutions at the
surface today, but the NAM and Canadian keep the Cold Bay low
deeper than other models as it moves north tonight and Mon. The
NAM and Canadian also form a deeper low just north of Barter
Island on Mon than other models do. Favor a blend of the NAM and
Canadian models at the surface through Tue, with winds increased
above models several kt along the West Coast through tonight.
Expect chinook winds gusting to 50 mph through ALaska Range Passes
today to decrease this afternoon. Expect north winds 20 mph with
gusts of 30 to 40 mph to develop along the West Coast and lower
Noatak Valley today, with gusts 50 to 60 mph developing today in
the Bering Strait, at St Lawrence Is and near Point Hope. Those
winds should decrease Mon night. Expect NE winds 20 to 30 mph
along the Western Arctic Coast tonight and spread to the Eastern
Arctic Coast on Mon. Could see west winds of 25 to 35 mph along
the Eastern Arctic Coast Mon PM into Tue. These windy areas of the
West Coast and North Slope could see Blizzard or near Blizzard
conditions in falling and blowing snow.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
AK...Winter Storm Warning for AKZ801.
     Winter Weather Advisory for AKZ802-803.
     Wind Advisory for AKZ849.
     Winter Weather Advisory for AKZ814-815.
     Winter Weather Advisory for AKZ818.
     Winter Storm Warning for AKZ820-821-827.
     Winter Weather Advisory for AKZ822-824.
     Winter Storm Warning for AKZ823.
     Winter Storm Warning for AKZ825.
     Winter Weather Advisory for AKZ826-830.
PK...Brisk Wind Advisory for PKZ801.
     Small Craft Advisory for PKZ802.
     Heavy Freezing Spray Warning for PKZ802-807-855.
     Small Craft Advisory for PKZ803.
     Heavy Freezing Spray Warning for PKZ803-804.
     Brisk Wind Advisory for PKZ805.
     Gale Warning for PKZ806.
     Gale Warning for PKZ807-816-851-856.
     Brisk Wind Advisory for PKZ808.
     Brisk Wind Advisory for PKZ809.
     Gale Warning for PKZ810-811-857.
     Brisk Wind Advisory for PKZ812-858.
     Brisk Wind Advisory for PKZ813-859.
     Brisk Wind Advisory for PKZ815.
     Gale Warning for PKZ817.
     Gale Warning for PKZ850.
     Brisk Wind Advisory for PKZ852.
     Gale Warning for PKZ853.
     Storm Warning for PKZ854.
     Small Craft Advisory for PKZ855.
     Brisk Wind Advisory for PKZ860.
     Brisk Wind Advisory for PKZ861.
&&

JB