Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 232116
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
116 PM AKDT Tue May 23 2017

.DISCUSSION...

Models...Initialize well against the 23/18Z local surface
analysis, but they diverge significantly past 90 hours or so.
Quite a bit of similarity in the precipitation patterns as well
in the short term. Will lean on an even blend for the first 48
hours, then more of a means based forecast beyond that due to
the diverging solutions with this progressive pattern.

Aloft...At 500 hpa...A 528 dam low in the central arctic will
move west and dissipate by Wednesday night. A 538 dam low over the
Northwest Territories of Canada will move southeast. A weak ridge
over the AlCan border with a 546 dam center over Mackenzie Bay
will be enhanced as ridging over the northeast Pacific builds
north. The axis of the ridge will move over the Yukon Territory by
Wednesday morning, and the ridge will slide east. A 517 dam low
over the northeast Bering Sea will split with a 523 dam low
diving southeast over the lower Kuskokwim Delta before filling
and being absorbed back into the primary low. The primary low will
move northeast over Kotzebue Sound, then over the Chukchi Sea by
Thursday afternoon. A low that develops over Wrangel Island
Wednesday morning will rotate southwest over the Gulf of Anadyr by
Thursday morning, then be absorbed into the primary low. A
shortwave extending from the primary low lies over the southern
Seward Peninsula to Lake Minchumina, to Yakutat this afternoon and
will move over the interior this evening and over the arctic
coast Wednesday morning. Several shortwaves will rotate over the
state through Friday, but timing them individually will be
difficult. At 850 hpa...Zero isotherm lies from Nuiqsut to
Anchorage with warmest temperatures to the east. It will push west
a bit to lie from Barrow to Kodiak City by Wednesday evening
before it is pushed back to the east as cold air from Siberia
rotates around the low aloft over the west coast and into the
interior pushing temperatures Friday to 5C to 10C below over the
forecast area.

Surface...Arctic front has been pulled back down over the
northwest coast and will hang around over that area for a few
days. Trough of lower pressure lies over the south slopes of the
Brooks Range. Weak ridging over the southeast interior and AlCan
border will break down as a 1005 mb low develops over Bristol Bay
this evening and moves over the lower Yukon Delta at 1000 mb by
Wednesday morning. The primary surface low south of the Gulf of
Anadyr will move over St Matthew Island by Wednesday afternoon as
it weakens to 998 mb. The low over the lower Yukon Delta will
continue to develop as it moves over the Seward Peninsula by
Wednesday afternoon at 992 mb and eventually absorbs the low over
St Matthew Island. A leeside trough will develop north of the
Alaska Range tonight and a strong pressure gradient will develop
across the Alaska Range. The gradient will relax Thursday as the
low moves over the Chukchi Sea and the trough/front move north
over the arctic coast by Thursday morning, and into the arctic by
Thursday evening. Weak ridge of high pressure will move over the
interior behind the front.

Arctic Coast and Brooks Range...Stratus that has been over the
area for the past few weeks continues to be the biggest issue.
Visibility will be up and down in fog and snow for most areas.
Heaviest snow will be over the northwest coast with 2 to 4 inches
possible. Heaviest snow will be around Point Lay and in the
western Brooks Range where up to 5 inches of snow is expected.
Winds mainly northeast to east today becoming southeast over the
western arctic coast as the low moves into the Chukchi Sea.
Temperatures not changing much tonight, then a bit cooler as so
cold air moves into the area.

West Coast and Western Interior...Rain showers will be the
primary weather with some snow showers over some of the higher
elevation areas and along the Chukchi Sea coast and Kotzebue Sound
during the overnight hours. Heaviest snow will be in the higher
elevations, but Shishmaref and Point Hope may see a couple inches
of fresh snow as the cold air is pulled in behind the low. Expect
up to 5 inches of snow along the south slopes of the western
Brooks Range as well. Some isolated thunderstorm activity
possible, but with cooling temperatures it should be suppressed
quite a bit.

Central and Eastern Interior...Cloudy to mostly cloudy conditions
will prevail the next couple days with some showers moving
through the area. Chinook winds developing tonight may keep most
of the showers north of the Tanana Valley. Winds increasing
overnight in the Alaska Range will be gusting to 50 to 60 mph, so
will be issuing Wind Advisories for zones 223, 225, and 226.
Rainfall in the interior generally less than a tenth of an inch,
but some heavy snow expected in Denali Park so will issue a Winter
Weather Advisory for up to 11 inches of snow, mainly in Denali
Park from Polychrome Pass west. Snow already being report along
the park road to Kantishna and webcams show fresh snow earlier
today and fog in the mountains. Snowfall on Denali will be
measured in feet the next couple days as cooler air and heavy snow
moves over the mountain. Temperatures in the interior a bit
warmer tomorrow with the Chinook flow, then cooling as cold air is
pushed east across the state.

&&

.FIRE WEATHER...Quiet at the moment with Relative Humidity values
generally above 30 percent and expected to remain that way for a
couple more days as cooler temperatures move into the area. The
upper Tanana Valley is the driest area, but the strong winds
expected through the Alaska Range passes tonight and Wednesday
will be west of the Tok Cutoff. Thunderstorm Activity continues to
be low and fairly spread out. Highest probability for
Thunderstorms Wednesday and Thursday will be southwest interior,
then northeast interior Friday. Snow will put a damper on any fire
activity potential in the western Alaska Range.

&&

.HYDROLOGY...Some small rises noted in interior streams from the
rain the past couple days, but nothing significant. Breakup
continues on the arctic plain with some open flowing water on the
Colville and Itkillik Rivers. A small ice jamb was noted on the
Itkillik River, but no issues reported so far. Meltwater continues
to collect in the frozen channels.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...

Winter Weather Advisory for AKZ225.

Wind Advisory for AKZ223-AKZ225-AKZ226-AKZ227.

&&

$$

SDB MAY 17



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