Heavy Freezing Spray Warning 32, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
450 AM AKDT Thu Oct 28 2021

.SYNOPSIS...
Quiet weather across northern Alaska this morning, with most
locations having cloudy skies. Light snow mixed in with fog
continuing across the northern Arctic Coast as the weather front
lifts offshore today. Occasional foggy conditions in the Interior
through this morning, while snow showers persist across the West
Coast. A persistent surface low off the northwest Arctic Coast is
bringing elevated surf from Point Hope to Shishmaref through
today.

The forecast becomes more challenging going into the weekend as a
strong surface low pressure moves into the Gulf of Alaska on
Friday night. This feature will result in strong southerly flow
developing across the Interior, particularly for the Alaska and
Brooks Ranges Saturday morning. Additionally, heavy snow is
expected to develop across the Central and Western Interior
starting Saturday and lasting into early next week.

&&

.DISCUSSION...
The upper level pattern consists of a longwave trough stretching
from the Chukchi Sea south to Bristol Bay and into the northern
Pacific Ocean. This is creating southerly flow across the eastern
portion of the state this morning. The southern portion of the
longwave trough will move eastward into the Gulf of Alaska where
it will rotate northward tonight and send a shortwave north of the
Alaska Range by Friday afternoon. Behind that shortwave, strong
ridging will build across British Columbia and into the Yukon
where strong southerly flow will develop. Another strong closed
upper level low will move north into the Gulf of Alaska,
reinforcing this southerly flow pattern on Saturday and lasting
through the rest of the weekend. At this point, models diverge on
the details but the long wave trough out west in the Bering Sea
will be around 500 dm while the strong ridge centered over British
Columbia will be around 565 dm on Sunday morning.

At the surface, a 100 mb low continues to persist just west of
Point Hope this morning. This low will weaken, but most models
struggle on where this feature will move; however, most solutions
show movement to the north which will result in the high surf
issues from Point Hope to Shishmaref to end. Otherwise, general
low pressure will remain out west, resulting in unsettled weather
with snow showers through the Bering Strait south.

The feature of interest for the short term will be a strong
surface low tracking from the northern Pacific into the Gulf of
Alaska beginning on Friday night. This low will continue to move
north, with a weather front bringing snow in the Western Interior
beginning late Friday and early Saturday. This front will spread
snow northward to the central Brooks Range by Saturday afternoon.
This front will then move to the west before models diverge on how
long the front will bring snow to the Western Interior and West
Coast going into Sunday. Regardless of the uncertainties in these
details, this will be a significant winter storm for the Western
Interior and portions of the West Coast this weekend.

Eastern and Central Interior...
The main impactful weather in the Interior going into and through
the weekend will be winds in the Alaska Range. Weak southerly flow
will develop through Alaska Range passes this morning and continue
into tomorrow. At that point, a strong surface low moving into the
Gulf of Alaska combined with strong southerly flow in the upper
levels will support a rapid increase in south winds through the
passes beginning tomorrow night and lasting into Saturday night.
Therefore, High Wind Watches remain in effect for southerly winds
gusting to 70 mph in the Alaska Range as well as southeast winds
gusting to 60 mph through Delta Junction south. East to southeast
winds will also increase across the Interior on Saturday as well,
with gusts to 35 mph in higher terrain. Areas from Tanana east
will remain precipitation free due to the strong chinook pattern
through the weekend. This strong southerly flow will result in an
increasing temperature trend, with areas in the Tanana Valley
reaching into the 40s by Saturday.

North Slope and Brooks Range...
Light snow and fog continue across the Arctic Coast this morning.
The weather front associated with this snow will continue to lift
to the north offshore today, with snow tapering off this
afternoon. Easterly flow will turn southerly tonight. Skies are
expected to clear for areas across the North Slope beginning
tonight, resulting in a cooling trend going into the weekend. At
that point, temperatures will be on a warming trend again as the
southerly flow strengthens across the Brooks Range. Winds in the
Brooks Range are expected to increase out of the south as well
during this time, with the south winds reaching the 40 to 50 mph
range through Atigun Pass on Saturday.

West Coast and Western Interior...
Periodic snow showers continuing for areas through the Bering
Strait and St. Lawrence Island this morning. These conditions
expected to persist through today as a surface low continues to
sit in the same general area off the northwest Arctic Coast. This
feature is also the cause for potential elevated surf of 1 to 2
feet from Point Hope to Shishmaref through today. The focus will
then shift to a snow storm that will develop across the Western
Interior beginning late Friday night. A weather front will push
northward into the lower Yukon and Kuskokwim Valleys late Friday
night, and then to the Upper Kobuk and Noatak Valleys by Saturday
morning. This front will then persist over the general area
through Saturday before drifting to the west along the Nulato
Hills and into the far eastern portions of Norton and Kotzebue
Sound by Sunday morning. Generally 5 to 10 inches are expected
for the areas mentioned in the Western Interior from Saturday
morning to Sunday morning. Winter Storm Watches are in effect due
to these snow amounts starting on Friday night and lasting into
Sunday morning. There remains a decent amount of model uncertainty
regarding the intensity and location of the weather front going
into Sunday, so will have to keep a monitor on how model guidance
handles the later stage evolution of this event. Temperatures will
warm slightly going into the weekend for the Western Interior,
while areas along the coasts will remain in the low to mid-20s.

Coastal Hazard Potential Days 3 and 4...A strong surface low
developing in the Kotzebue Sound to northwest Arctic Coast region
will increase potential for elevated surf from Shishmaref to Point
Hope beginning Sunday afternoon and lasting into Monday morning.
However, model discrepancies on surface low placement and
associated wind field is keeping confidence in the low to moderate
range at this time.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Wind Watch for AKZ223-AKZ225-AKZ226.

Winter Storm Watch for AKZ215-AKZ216-AKZ217.

Small Craft Advisory for PKZ220-PKZ225.

&&

OCT 21