000
FXAK69 PAFG 232347
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
347 PM AKDT Mon Apr 23 2018

.SYNOPSIS...
Aloft...
A long wave pattern consisting of a ridge over NW Canada and NE
Alaska trough over the Bering Sea and NW Pacific will progress
east to a trough position over the West Coast of Alaska Wed, and
over the Western Interior of Alaska Thu as a series of
progressively stronger short wave troughs make their way NE
across Alaska through Wed. This will mean wet and windy conditions
along the West Coast and Western Interior of Alaska through Thu,
while the Eastern Interior has a strong warming due to chinook
conditions tonight and Tue, while the Arctic sees a warm up Wed.

Northern Alaska entering a progressive long wave pattern late this
week into next week with a series of strong short waves and SW
flow over Northern AK keeping conditions much wetter than normal
and warmer than normal.

most of the short wave troughs are associate with surface fronts
and will be addressed with surface weather below.

Surface...
A strong ridge of high pressure north of the Arctic Coast will
persist through Tue, then weaken slowly Wed and Thu. East winds
along the Arctic Coast will persist through Tue night.

An arctic front from Eagle to Nome, will move to Eagle the Bering
Strait by 4am Tue, along the Brooks range by 4pm Tue, along a
Barter Island to Point Lay line by 4am Wed, and along a Barter
Island to Wainwright 4pm Wed, then dissipating. East winds 15-25
kt along and north of this front will persist through Tue PM. This
is causing blowing snow in the Western Arctic Coast.

An old occluded front from Gambell to the YK Delta will move to
the Bering Strait to Huslia by 4am Tue, and then diminish over NW
Alaska Tue pm. Expect rain and snow with this front. Could see 1-2
inches above 2000 feet, but little accumulation below 2000 ft.

Another occluded front stretching from Cordova to Dawson will move
Fort Yukon east by 4am Tue. Expect isolated snow showers with this
feature.

A 970 mb low in the southern Bering Sea will move to near the
Pribilof Islands as a 976 mb low by 4pm Tue, and then dissipate
over the YK Delta early Wed. An occluded front stretching
northeast from this low will move to St Mathew Island to a 977 mb
frontal wave low near Nunivak Island by 4am Tue.

The frontal wave low will move to near St Lawrence Island as a
969 mb low by 4pm Tue, near Gambell as a 981 mb low by 4pm Wed,
and to near the Bering Strait as a 993 mb low by 4pm Thu. Expect
winds 25-30 kt circling this low.

A Cold front extending SW from this low will move to Savoonga to
Nome to McGrath to Homer by 4pm Tue, to Provideniya to Point Hope
to Northway by 4am Wed, to Anadyr to Wainwright to Barter Island
by 4pm Wed, then dissipating along the Arctic Coast. There will be
a warm front with this front moving over SW Mainland AK tonight,
to Nome to Eagle by 4pm Tue, to Umiat to Inuvik by 4am Wed, then
developing a 996 mb frontal wave over MacKenzie Bay by 4pm Wed.
will see SE winds 25 kt ahead of this front changing to s25 kt
behind the front.

Expect rain and snow to spread north over the West Coast and
Western Interior Tue with these fronts, over the Central and
Northern Interior Tue night, and over the Arctic Coast Barrow east
on Tue. Could see freezing rain on the eastern North Slope Tue.
Precip amounts range from .25-.75 in the West Coast and western
Interior, and to .10-.50 in the Brooks Range and eastern North
Slope. Will be mostly rain below 2000 ft, mix rain and snow above
2000, and all snow above 3000 ft with up to 4 inches above 3000
ft. Main impact will be Atigun Pass Tue night, and higher
elevations of Denali.

Will see very strong chinook over the Alaska range ahead of this
cold front developing after midnight tonight with the strongest
winds Tue, when gusts to 70 mph are expected. This will also cause
warm up into 50s over the Eastern Interior Tue with 60 possible.
Chinook will drop off after the cold front passes late Tue/early
Wed and then could see chance of rain and snow in the Eastern
Interior.

An Arctic Cold front in the Western Bering Will move to the
southeast Bering Tue pm, and to the Bering Strait to Anvik by 4pm
Wed, and to Point Lay to McGrath by 4pm Thu. Expect several inches
of snow with this. Will see SW winds 25 behind this front which
could cause elevated surf Wed and Thu south of the Bering Strait.


&&

.DISCUSSION...
Models initialize well above the surface and show similar
solutions through 4pm Wed, with increasing differences from Thu
into the weekend on timing and strength of short waves. All models
all initialize 4 mb too weak on the surface high north of the
Arctic Coast. Will use blend of GFS/NAM/ECMF through Thu with an
increase of 3-5 kt above models solutions in winds along the
Arctic Coast through Tue to account for the high pressure
remaining stronger than models indicate.

Entering a progressive long wave pattern by the weekend into next
week with a series of strong short waves and SW flow over
Northern AK. Ensemble approach might work with timing, but we will
expect surface low pressures to be deeper, similar to
deterministic fields. This is more of SW flow pattern typical of
fall than of spring, and we have seem much deeper storms the past
week then we normally see in April.

Coastal Hazard Potential Days 3 and 4...
Elevated sea levels Wed and Thu could cause high surf and push
ice onshore from the YK Delta to the Bering Strait.

&&

.FIRE WEATHER...
Strong chinook winds along the Alaska Range late tonight into
early Wed.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Advisory for AKZ217-AKZ219-AKZ223-AKZ224-AKZ227.

High Wind Warning for AKZ225-AKZ226.

Winter Weather Advisory for AKZ201-AKZ218.

Heavy Freezing Spray Warning for PKZ210.

Brisk Wind Advisory for PKZ215-PKZ220-PKZ225-PKZ230-PKZ235-
PKZ240-PKZ245.
&&

$$

JB APR 18