Area Forecast Discussion
Issued by NWS Fairbanks, AK

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383
FXAK69 PAFG 202249
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
149 PM AKST Sat Jan 20 2018

.DISCUSSION...
Main forecast concerns include wind chill hazards initially
through the first 24 to 48 hours and below normal temperatures
for the majority of Northern Alaska throughout the forecast
period. The 20/12Z models are in good agreement through 84 hours
with significant differences developing between the GFS, ECMWF,
and CanadianNH mid to late next week in the longwave trough and
axis over the region. General model consensus keeps the longwave
trough over Northern Alaska with its axis positioned west of a
line from Healy to Deadhorse. To the east of this axis, cloudy
conditions will continue to help moderate temperatures, while to
the west predominately clear skies will allow for strong
radiational cooling and will produce colder temperatures.

Arctic Coast and Brooks Range...Wind Chill Advisories remain in
effect over the area for zones 201-203 and 205-206. Despite
significant cooling over the Arctic Coast from Barrow west and
western Brooks Range (zones 201, 202 and 205), strong westerly
winds have weakened to between 10 to 15 mph and have consequently
resulted in a marginal case for a wind chill advisory. Along the
eastern Arctic Coast, wind chill advisories look solid as winds
chill values have been -50 or colder with winds sustained between
15 to 25 mph. Over the eastern Brooks Range, winds have been
generally between 10 and 15 mph with stronger winds through passes
between 20 and 30 mph with the coldest wind chill values found in
the passes. Have decided to cancel the wind chill advisories for
201 and 202 as forecast conditions are expected not to meet wind
chill thresholds. Elsewhere, winds will continue the downward
trend with the expectation that the wind chill threat will end by
tomorrow afternoon. Temperatures will remain near to below normal
through the forecast period with some warming hinted late next
week by the models.

Eastern and Central Interior...Generally cloudy skies and periods
of very light snow will persist east of a line from Healy to
Manley Hot Springs and Bettles. This will help to moderate and
keep temperatures warmer in the teens to 20s below than otherwise
would be if skies were clear. To the west of this line, generally
clear skies will allow for maximum radiational cooling and
temperatures to cool into the 30s and 40s below by tomorrow
morning. The aforementioned line will gradually shift westward
Sunday evening into early next week as an upper level low drifts
south from the Arctic and over Northern Alaska. This will help to
warm temperatures by a few degrees over the coldest areas.

West Coast and Western Interior...Maximum radiational cooling
under generally clear skies will allow for temperatures to drop
into the 30s and 40s below by tomorrow morning. A weak upper level
shortwave will bring a period of light snow and cloudiness to from
the Seward Peninsula south including the Bering Strait and Saint
Lawrence Island this evening into tonight. Snowfall accumulations
will be minimal...an inch at best. Once this moves off to the
south, temperatures will cool over this area. Winds have weakened
to below 10 mph in zones 209 and 210 and below the wind chill
advisory threshold for winds. However, over zones 208 and 217
breezy north winds through passes will weaken overnight tonight,
but will remain strong enough to meet wind chill advisory criteria
through tomorrow morning. Below normal temperatures will persist
across the region throughout the forecast period with model
guidance hinting at a gradual warmup mid to late next week.

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

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Wind Chill Advisory for AKZ203-AKZ205-AKZ206-AKZ208-AKZ217-
AKZ218.

Winter Weather Advisory for AKZ204.
&&

$$

LTH JAN 18



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