Blizzard in Alaska, March 21 to 23, 2019

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
320 PM AKDT Wed Mar 20 2019

.DISCUSSION...

SYNOPSIS...
Deep low pressure over the North Pacific along with very strong
high pressure over central Canada will continue to produce
unseasonable and in some cases, record warmth across the Central
and Eastern Interior. A front emanating north from the Pacific
low will essentially bisect the state from the southwest coast to
the eastern Brooks Range. Colder air on the west side of the
boundary will facilitate an all snow event as the front works its
way slowly west over the next few days. To the east of the front,
Chinook conditions will keep the Central and Eastern Interior free
of precipitation while acting to exacerbate the already
abnormally high temperatures across the region.

Aloft 500 mb...
A 573 dam high centered over Montana extends a broad ridge axis
northwest into the Alaskan Interior. A deep longwave trough over
much of the Bering Sea and western Alaska is anchored in place by
a 502 dam low in the North Pacific. These features will remain
relatively stagnant as they slowly weaken over the next couple of
days. The high amplitude of the longwave pattern will facilitate
persistent warm southerly flow into the Interior east of a well-
defined frontal boundary, with a cooler, Arctic airmass to the
west. As the North Pacific low begins to weaken, it will separate
itself from the longwave trough to become cutoff by Sunday. This
will allow a ridge to form over the central Bering as low pressure
over Kamchatka deepens and begins to track eastward towards the
West Coast. The front associated with this system will reach the
West Coast by Sunday and will be the harbinger of warmer unsettled
weather early next week for much of the state.

North Slope and Brooks Range...
Benign weather for the most part expected today as the region
remains clear of any major synoptic features at the surface.
Along the coast, a gradual northerly shift in winds is expected
this evening as a front moves up and over the eastern and central
Brooks Range. Wind speeds will increase to 10 to 15 mph as snow
associated with the front reaches the Beaufort coast. Areas east
of Nuiqsut may see visibility reduced to one half mile or less,
though snow accumulations will be generally be less than 2 inches.
Precipitations will diminish late Thursday as east winds begin to
further increase into Friday. Strong winds of up to 40 mph or
greater are expected along much of the Arctic Coast Friday as
high pressure to the north tightens the pressure gradient. Blowing
snow will become an issue during this time.

West Coast and Western Interior...
Strong high pressure over Siberia will resist the westward
progression of an occluded front from Interior Alaska. As the
front creeps west, northerly winds will increase, particularly
from the Norton Sound south. Snow and wind will result in reduced
visibility to one half mile or less at times, so Winter Weather
advisories remain in effect for the eastern Norton Sound and Yukon
Delta regions. The Western Interior mainly north of Anvik to
Huslia will see the greatest snow amounts through Thursday
morning, with 2 to 4 inches likely for most areas with isolated
amounts up to 6 inches. By Friday the front will have moved
offshore with St. Lawrence Island taking the brunt of the snow and
wind. Warmer temperatures will begin to creep northward into the
Y-K Delta Thursday as a weak surface low migrates northward from
the North Pacific. Warmer temperatures will mainly be confined to
this region through Saturday. The next major pattern shift is
expected Sunday as a deep Bering Sea low slides west, bringing a
reversal of winds and a messy mix of wintery precipitation and
rain.

Central and Eastern Interior...
Chinook conditions will keep much of the region free and clear of
precipitation with abnormal warmth continuing into the weekend.
Areas north of a line from Tanana to Fort Yukon including the
Dalton highway could see up to 2 inches of snow as a front tracks
northwest through the region tonight into Thursday morning.
Isolated amounts up to 4 inches are possible across the central
Brooks Range. East winds up to 30 mph over summits could reduce
visibility at times. Wind Advisories remain in effect for the
central Tanana Valley near Delta Junction as well as Eastern
Alaska Range Passes. Tanana Valley Jet winds up to 50 mph along
with southerly winds up to 65 mph through Isabel Pass are likely
through Thursday morning. These winds will tend to oscillate up
and down as a series of fronts associated with North Pacific low
pressure track up and over the Alaska Range over the next few
days.

Models...
No major malfunctions with regards to initialization vs obs at
18Z. Models maintain tight consistency with both longwave and
shortwave features through the weekend before significant
differences become apparent Monday with the GFS favoring quicker
deepening of the low in the central Bering Sea. Regardless,
significant evidence exists for a major pattern shift Monday as
strong dynamics come into play.

Coastal Hazard Potential Days 3 and 4...
There is potential for a strong low will move to the north
through the western Bering Sea Monday into Tuesday of next week.
Right now the models have significant differences on the evolution
of this system. Some of the model solutions show the potential
for elevated water levels along the west coast. We will have to
continue to monitor this system..

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ223-AKZ226.

Winter Weather Advisory for AKZ212-AKZ213-AKZ214-AKZ216.

Small Craft Advisory for PKZ230.

Gale Warning for PKZ210-PKZ220-PKZ225.

Brisk Wind Advisory for PKZ200-PKZ215-PKZ245.
&&

COWMAN MAR 19