Wind Advisory 4, NWS Fairbanks, AK

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
644 AM AKDT Tue Mar 17 2020

.SYNOPSIS...
Highlights are:
A weather front approaching the West Coast of Alaska today will
bring 2-6 inches of snow to the West Coast and Western Interior
today and tonight, with the heaviest amounts over south facing
slopes. There will be a chance of freezing rain just ahead of the
front south of Nome and Galena as well. Expect south winds gusting
30-40 mph and low visibility in blowing snow from the Bering
Strait to Cape Lisburne today and tonight. Expect these conditions
to spread to zones 201 and 202 from late tonight through Wed
afternoon as well. This front will bring 1-2 inches of snow to the
North Slope and Interior tonight and Wed as well.

A second, and much stronger storm will move into the West Coast
and Western Interior Wed night into Fri and bring southwest
gales, heavy snow, a chance of freezing rain, and blizzard
conditions. Can expect 6 inches of snow in most of the West Coast
and Western Interior Wed night through Fri, with over a foot on
south facing slopes. Expect Blizzard conditions along most West
Coast zones and zone 208. Expect snow to and a slight chance of
freezing rain spread to the Central Interior and south slopes of
the Brooks Range Thu, and across the Ern Interior Thu night and
Fri, with 3-6 inches of snow possible in the Ern Interior and
south slopes of the Brooks Range late Thu into Fri. This will
bring a chance of snow and blowing snow to the Western North Slope
Thu into Fri.

These strong southwest winds will cause sea levels to rise 3-4 ft
above normal along the West Coast Thu and Thu night, and could
cause water to seep up between cracks in ice near the coast.

Aloft...
The long wave pattern consists of a strong ridge aloft stretching
from the NE Pacific north over Mainland Alaska with a deep trough
over the NW Pacific and NE Russia. This pattern and its moist SW
flow will persist through the end of the week, with a series of
strong short wave troughs moving northeast across the Bering Sea
and Northern Alaska. This will cause all of Northern Alaska to
remain much warmer than normal through the end of the week, with
periods of snow. Heavy snow can be expected at times along the
West Coast and NW Alaska, and there will be a chance of freezing
rain south of the Brooks Range.

A strong short wave trough over the Eastern Bering Sea will move
over the West Coast by 4pm Tue, and then continue east to the
Alcan Border by Wed afternoon. Snow will spread northeast across
Northern Alaska ahead of this trough, with sharp ridging and
clearing of clouds occuring just behind the trough.

A second and much stronger short wave in the NW Pacific will move
to the Central Bering Sea by 4pm Wed, then over the Western Alaska
of Alaska by 4pm Thu, and tot he Alcan Border by Fri morning. This
system has tapped into significant moisture and is expected to
bring heavy snow to the West Coast and Western Interior Wed night
through Fri, and moderate snow amounts to the Ern Interior Thu-
Fri.

850 MB temps are similar between models. Temps riding to 0C just
ahead of incoming front today will bring a slight chance of light
freezing rain along the leading edge of the precip. Much stronger
warm advection ahead of the second front approaching the West
Coast and Wrn Interior on Wed and Wed night, and over the North
Slope and Ern Interior on Thu. This will bring chance of freezing
rain to the West Coast and Wrn Interior Wed and Wed night and to
the Ern Interior Thu.

Surface...
An arctic front from Northway to Utqiagvik north will move to
Dawson to Kaktovik to north of Utqiagvik by pm4 Tue, then moving
northeast on Wed. FLurries occuring along this front will
diminish south of the front.

A 988 mb low 300 NM west of Wrangel Island will move to 300 NM
northwest of Wrangel Island as a 986 mb low by 4pm Tue, and then
continue north. A weather front stretching from this low to the
southeast Bering Sea will move along the West Coast of Alaska by
4pm Tue, to Utqiagvik to Minchumina by 4am Wed, to the Alcan
Border by 4pm Wed, then continue east. This will bring 3-6 inches
of snow to the West Coast and Wrn Interior today and tonight with
the heaviest snow in south facing slopes. Expect south winds
20-30kt along the front turning SW 25kt behind the front. This
will bring blowing snow with low visibility to zones 213 209 208
207 today and to zones 201, 202 and 206 tonight. There will be
periods of rain and freezing rain ahead of the front over zones
214 and 215 today, with a slight chance of light freezing rain at
the outset of precip ahead of the front before evaporative cooling
with heavier precip cools the airmass below freezing. There is a
chance of blowing snow and low visibility over zones 203 and 204
on Wed with the front if falling snow occurs.

A very strong weather front will move north over the Bering Sea
Wed to along the West Coast of Alaska by 4am Thu, and to Deadhorse
to Mcgrath by 4pm Thu. Can expect 6 inches of snow in most of the
West Coast and Western Interior Wed night through Fri, with over
a foot of snow on south facing slopes. There will be a chance of
freezing rain ahead of the front as well. Expect Blizzard
conditions along most West Coast zones and zone 208. Expect snow
and a slight chance of freezing rain to spread to the Central
Interior and south slopes of the Brooks Range Thu, and across the
Ern Interior Thu night and Fri, with 3-6 inches of snow possible
in the Ern Interior and south slopes of the Brooks Range late Thu
into Fri. This will bring a chance of snow and blowing snow to the
Western North Slope Thu into Fri.

&&

.DISCUSSION...
Aloft at 00Z, models initialize well and show similar solutions
through Thu, with model solutions starting to spread Thu night.

Precipitation areal coverage and amounts are similar for the GFS,
NAM and ECMF through 4am Thu, with the ECMF moving the precip
east more rapidly on Thu. At this time favor a blend of the NAM
and GFS for precip, as the ECMF appears too fast moving the front
and precip eastward into the ridge aloft.

At the surface at 06Z, models verify well on most features. Models
show similar solutions through Thu, but the NAM and ECMF keep
wind along the coast s a few kt stronger than the GFS. Given the
highly dynamic pattern we are now in which could easily deepen
systems more than forecast, we will opt to go with the slightly
stronger winds of the NAM/ECMF for the coasts through Thu.

Bottom line is, we will use a blend of the NAM/GFS/ECMF through
4pm Wed, then use a blend of the NAM and GFS for precip, temps for
Wed night and Thu. Will use the NAM for winds through Thu.

Coastal Hazard Potential Days 3 and 4...
Southwest gales will bring heavy snow and local blizzard
conditions to the West Coast Thu into Fri, This will also cause
sea levels to rise 3-4 ft above normal along the West Coast Thu
and Thu night, and could cause water to seep up between cracks in
ice near the coast.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Winter Weather Advisory for AKZ201-AKZ202-AKZ206-AKZ207-AKZ208-
AKZ209-AKZ213-AKZ214-AKZ215-AKZ217.

Brisk Wind Advisory for PKZ200-PKZ210-PKZ215-PKZ220-PKZ225-
PKZ235-PKZ240-PKZ245.
&&

JB MAR 20