Area Forecast Discussion
Issued by NWS Fairbanks, AK

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FXAK69 PAFG 221233
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
433 AM AKDT Sun Apr 22 2018

.DISCUSSION...

Aloft...
High pressure ridge centered 100NM west of Wrangel Island will
slowly weaken but continue to provide stability across the
northern portion of the state through Tuesday. Broad mid LVL low
pressure over the Bering Sea containing several distinct height
minima will begin to coalesce and deepen as an organized,
vertically stacked low, reaching just south of St. Lawrence Island
early Wednesday. A series of shortwaves associated with this
Bering Sea system will move south to north across the Interior
during this time, providing a setup for precip across the West
Coast and Chinook conditions north of the AK Range. By Thursday,
the Bering low will weaken and track eastward and high pressure
will build back across the Arctic shores, resulting in a more
stable pattern late in the week.

North Slope...
Broad sfc high pressure centered in the northern Chukchi Sea
continues to provide stability across the North Slope. Low stratus
over Point Barrow associated with a weak sfc trough just east of
the high will erode as the high tracks eastward. The high will
continue to retreat eastward towards Banks Island as the first of
the aforementioned shortwaves reaches the North Slope late
Monday. Increasing cloud cover through Tuesday will be followed by
areas of snow Wednesday. A leeside low will develop over Barter
Island Wednesday and will support heavier snow north of the
eastern Brooks Range and along the Beaufort Coast. High pressure
will return to the coast late Thursday with clearing conditions
expected thereafter.

West Coast and Western Interior...
Benign conditions will continue through the weekend for most of
the region. Gusty NE winds across St. Lawrence Island can be
expected Sunday evening into Monday. By early Monday, shortwave
number 1 will move north into the Yukon Delta, providing rain for
areas east of the Kuskokwim Mountains. Snow may mix in at higher
elevations. Heavier precip is expected Tuesday in these same
locations as the sfc low nears the coast by Cape Romanzof and the
second of a series of shortwaves tracks through the area. Highest
precip totals can be expected in the Nulato Hills due to southeast
flow and upslope forcing. Rain can be expected as far north as
Cape Lisburne, where daytime high temperatures will reach above
freezing. Showery conditions will gradually taper off through
Friday as the sfc low tracks south.

Central and Eastern Interior...
Southerly flow across the AK Range as well as ridging aloft has
combined to produce warming temperatures and clearing conditions
across the Tanana Valley. The Chinook effect will persist and
amplify over the next few days and will act to shield this area
from any precip associated with the shortwaves transiting the
region. However, areas of the AK Range can expect snow beginning
Monday evening and increasing into Wednesday. Additionally, a
strong southerly low-mid LVL jet will act to enhance the Chinook
winds late Monday into Tuesday. Very strong winds are likely
across mountain peaks as well as through passes. This, combined
with heavy snow accumulations over 1 ft. will make conditions near
Mt. Denali particularly hazardous through Thursday. Advisories
may be warranted during these times.

Models...
Model concensus remains tight through Thursday will all solutions
favoring the pattern described above. The ECMF does seem to keep
the Bering low significantly weaker than all other guidance,
therefore the GFS was chosen as the going standard for the latter
half of the week.

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

&&

.FIRE WEATHER...
Chinook conditions along the Tanana Valley will feature low RH
values and warmer temperatures across the entire area as well as
strong S winds spanning the northern slopes of the AK Range. These
winds could reach as far north as Delta Junction at times,
resulting in abrupt shifts in wind direction and speed. These
conditions will be strongest Tuesday and Thursday.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
High Wind Watch for AKZ226.

Heavy Freezing Spray Warning for PKZ210.

Small Craft Advisory for PKZ210.
&&

$$

COWMAN APR 18


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