Area Forecast Discussion
Issued by NWS Fairbanks, AK

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128
FXAK69 PAFG 222151
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
151 PM AKDT Tue Aug 22 2017

.DISCUSSION...
Unsettled, showery, and cool pattern will persist across Northern
Alaska as a longwave trough remains the dominant synoptic feature
overhead. Main forecast concerns are potential for snow along the
Brooks Range tonight and Wednesday night, and high surf along the
southern Chukchi Sea from Cape Espenberg west to the Bering
Strait. 22/12Z deterministic model solutions are similar through
12Z Friday, with increasing differences in solutions thereafter.

Aloft...Longwave trough remains over mainland Alaska stretching
from the North Pole south over Alaska and towards 50N. This
longwave trough will remain over Alaska through next weekend
before an upper level ridge builds north from the Pacific
Northwest and over eastern Interior early next week. There are
and will be several lows and shortwaves that will move within
this longwave trough. A 540 dam upper low over northwest Alaska
will dig south to be over the Seward Peninsula by Wednesday
afternoon. This low will split as one piece of energy moves south
to be over Bristol Bay, while the other moves northeast and forms
a new upper low roughly 260 NM northeast of Deadhorse Thursday
evening. A shortwave rotating around the aforementioned low will
move east over the Middle Yukon Valley this afternoon, and over
the Central Interior/Middle Tanana Valley tonight, then lift to
the Brooks Range by tomorrow afternoon. A low originating from the
northwestern Pacific will move towards Bristol Bay and will
eventually weaken and swing east and into the Gulf of Alaska by
Wednesday night. H850 temperatures will steadily cool over the
North Slope and Western Alaska. H850 temperatures over the North
Slope and Brooks Range will cool by 5C to 10C from today with
values -2C to -6C by Thursday evening. H850 temperatures along the
West Coast will fall to around 0C by Thursday evening.

Surface...A 1004 mb low over Point Hope will move inland over the
Northwest, weaken, and become a part of a weak surface trough
extending west to east over the North Slope. A 1000 mb over the
Gulf of Alaska will move east and inland over the SE panhandle
tonight. A 996 mb low situated north of the Aleutian Islands will
move east and be over Bristol Bay by Wednesday evening. Surface
high pressure extending from the high Arctic and over Siberian
Russia will persist and will spread south and over the Bering sea
by the end of the week.

North Slope and Brooks Range...Main concern will be the snow at
higher elevations within the Brooks Range during the overnight
periods through Friday morning. As temperatures cool aloft and at
the surface, snow levels will descend in elevation some tonight,
then to around 2000 feet Wednesday and Thursday night. Snowfall
accumulations in high elevations west of Anaktuvuk Pass will be 1
to 3 inches tonight, 2 to 5 inches Wednesday night, and 1 to 3
inches Thursday night. For Anaktuvuk Pass and Atigun Pass along
the Dalton Highway, will see less than an inch tonight, around an
inch Wednesday and Thursday night. Areas of fog will redevelop
late this evening and dissipate Wednesday morning with cloudy
skies persisting.

West Coast and Western Interior...Main concern is the ongoing High
Surf Advisory along the southern Chukchi Sea from Cape Espenberg
west. West winds sustained between 25 to 30 mph have been
observed at Shishmaref with winds and high surf expected to
persist through this evening before dissipating. Have updated the
high surf advisory and will continue it as is through Midnight.
Cooling temperatures are expected as colder air is funneled
southward over the next couple of days. This colder air may bring
a chance of accumulating snow with 1 to 2 inches possible in the
Upper Noatak and Kobuk Valleys Wednesday night. Otherwise,
cloudy and showery pattern will persist.

Eastern and Central Interior...Isolated to scattered showers
tonight as an upper level shortwave moves east over the Interior
with a brief break in showers Wednesday evening and night. More
showers expected Thursday and Friday. For the Alaska Range,
scattered to numerous showers will persist throughout the week.
Temperatures will warm by a few degrees Thursday and Friday over
the eastern Interior as a warmer airmass is pushed north. Gap
winds 15 to 30 mph through Alaska Range passes are expected Thursday
and Friday.

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

&&

.FIRE WEATHER...No concerns as conditions remain cool and moist.


&&

.HYDROLOGY...Rivers steady or trending down the next couple days.


&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Surf Advisory for AKZ207.

Small Craft Advisory for PKZ220.
&&

$$

LTH AUG 17



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