Heavy Freezing Spray Warning 7, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
341 PM AKDT Tue Oct 5 2021

.SYNOPSIS...

A low pressure system is currently bringing a mix of rain, snow,
and heavy snow to the West Coast and Western Interior. This system
will bring heavy snow to areas of the Central and Northern
Interior west of a line from Tanana to Atigun Pass through
Thursday night. Precipitation will reach Fairbanks by late
tomorrow night beginning as snow then becoming a mix of rain and
snow, with more of the precipitation falling as snow at higher
elevations. Southerly gap winds in the Alaska Range will also
increase tonight and tomorrow with gusts to 65 mph before quickly
diminishing Wednesday night. Another low pressure system from the
Bering Sea will bring more precipitation to the Yukon Delta and
southwest Alaska by early Friday morning.

&&

.DISCUSSION...

The 05/12z model suite generally has good agreement through the
short term forecast period and even into the medium range. Models
initialized well aloft when compared to upper air observations. At
the surface, models initialized well except a low near Shemya is
4 to 6 millibars deeper than models initialized. This low will
deepen as it moves to the Yukon Delta by tomorrow morning, with
the NAM being the deepest solutions at 979 mb by the time the
feature reaches Norton Sound. We will trend toward the deeper
model solutions on this feature and increase winds above model
guidance to account for this difference between models and
observations. The deeper low in Norton Sound will also tighten a
surface gradient across the Alaska Range, so we'll also bump winds
through Alaska Range passes above model guidance on Wednesday and
on Wednesday night.

Aloft at 500 mb, weak southwest flow persists over most of the
Mainland driven by a 522 dam low in the far SW Bering Sea and a
528 dam low 120 miles north of Utqiagvik. The low in the SW Bering
will move to near Gambell by early tomorrow morning as a fast
moving shortwave moves to the Yukon Delta and merges with the low
late tomorrow morning. The low north of Utqiagvik will slowly
drift north as the newly formed combined upper level low and
associated trough moves inland. By Friday morning, another low
from the Bering Sea will move to near Dillingham, leaving most all
of the Mainland in a trough heading into the weekend.

At the surface, high pressure persists but is weakening over the
Yukon Territory. A 982 mb low in the western Bering Sea will
remain in place and merge with a 979 mb low near the Yukon Delta
on Wednesday morning. At that time a weak south to north pressure
gradient across the Alaska Range that is already in place will
strengthen. The gradient will briefly reach as much as 9 to 10
millibars across the AK Range, but will weaken quickly Wednesday
night as another low pressure system moves into the Gulf of
Alaska. High pressure will persist over the high Arctic.

Central and Eastern Interior...Mainly dry conditions today will
end for areas west of Fairbanks tomorrow as a mix of
precipitation pushes east. Heavy snow is expected for areas at
elevation north and west of Minto through Thursday with localized
accumulations up to 12 inches. Lower elevation areas can expect 4
to 7 inches, but 5 to 10 inches from Indian Mountain north.
Precipitation will reach Fairbanks overnight Wednesday night into
Thursday and start briefly as snow before changing to a mix of
rain and snow and eventually to all rain during the day Thursday.
At this time very little snow accumulation is expected at valley
level, though messy conditions are expected Thursday morning.
Areas above 2000 feet can expect 1 to 3 inches of snow
accumulation. Precipitation will taper off Thursday night into
Friday. Southerly winds in the Alaska Range will also increase
overnight tonight and through tomorrow with gusts to 65 mph before
diminishing Wednesday night.

North Slope and Brooks Range...Heavy snow is expected on the
south slopes of the Central and Western Brooks Range through
Thursday night with storm totals of up to 12 inches. Southerly gap
winds are also expected to increase tonight and peak tomorrow
before diminishing Wednesday night. Fog and stratus from
Deadhorse to just east of Utqiagvik has pushed offshore this
afternoon, but remains around Utqiagvik and Kaktovik. Southerly
flow will allow this area to remain fog and stratus free through
tomorrow. Lows temperatures will be in the teens and twenties and
high temperatures will be in the twenties and thirties.

West Coast and Western Interior...Expect a mix of rain and snow
today changing over to mostly all rain overnight for areas not at
elevation. Rain is expected to intensify tomorrow morning mainly
from Nome south. Rain is expected to lighten up Thursday through
the day from west to east. Another system will bring a mix of snow
and rain to the Yukon Delta and Lower Yukon Valley on Friday. Low
temperatures will be in the thirties with highs in the low to mid
40s.

Extended Forecast for Days 4 through 7...The low pressure system
bringing precipitation to the Yukon Delta and Lower Yukon Valley
on Friday will slide east over Southcentral Alaska on Saturday,
leaving all of the Mainland under a troughing pattern. The Central
and Eastern Interior including Fairbanks will see a chance of snow
this weekend before a weak ridge builds in early next week. A
weather front will arrive at the West Coast on Monday, bringing
more precipitation.

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

&&

.HYDROLOGY...Areas of the West Coast from Nome to the Yukon Delta
have received as much as an inch of rain in the past 24 hours and
are forecasted to receive an additional 1/2 inch to 1 inch through
tomorrow night. Rivers in this area will rise, but flooding is not
expected.

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ225-AKZ226.

Winter Storm Warning for AKZ216-AKZ217-AKZ218-AKZ219-AKZ221.

Winter Weather Advisory for AKZ208.

Heavy Freezing Spray Warning for PKZ235-PKZ240-PKZ245-PKZ500-
PKZ505-PKZ510.

Small Craft Advisory for PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-
PKZ230-PKZ235.
&&

CHRIEST OCT 21