Area Forecast Discussion
Issued by NWS Anchorage, AK

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214
FXAK68 PAFC 181322
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
422 AM AKST Wed Jan 18 2017

.ANALYSIS AND UPPER LEVELS...
The upper level flow pattern remains centered around a very cold
upper level low centered over northwestern Alaska and trough
extending into Southwest Alaska. An inverted surface trough along
the northern Gulf coast is strengthening as a low in the far
southern eastern Gulf tracks towards the Panhandle strengthening
north to northwesterly offshore flow. In the Bering, a surface low
north of Atka is rapidly spinning up as it tracks north-northeast.

&&

.MODEL DISCUSSION...
While model solutions are improving in consistency regarding the
initial northeastward track of the developing low in the Bering
through this evening, they still continue to diverge significantly once
the low turns east. The 00Z Canadian appears the outlier taking
the low well to the south of the other runs and tracking it to the
southeast and across the western tip of Alaska Peninsula. The 00Z
GFS and EC have come into better agreement, both taking the low
east from the Pribilofs into Bristol Bay. The 00Z NAM split the
difference between the Canadian and GFS/EC tracks, while 06Z NAM
came in close to the the GFS/EC though slightly slower. The 06Z
GEM Regional also came in further north though faster than the
other models.

For the eastern domain, model consistency remains good and the
NAM was preferred in the short term for its handling of the
outflow winds.

&&

.AVIATION...
PANC...Low clouds and patchy areas of fog in the vicinity of PANC
are expected to diminish through the morning as a dry and very
cold air mass continues to push into the area. VFR conditions are
expected to persist through into Thu.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
An upper level trough will slide east through Southcentral Alaska
through Thursday and into northwest Canada Thursday night. An
upper level ridge will build in behind this low. At the surface,
fairly strong offshore flow will continue Through Thursday and
then begin to weaken Thursday night. A very cold air mass will
remain over the area, with temperatures over most of the interior
remaining below zero.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA...
The cold airmass that has been sitting over southwest Alaska will
finally get pushed out as a warm front moves in from the southwest
today. Even though temperatures will rise from the warmer air it
will remain cold enough to see only snow. The snow be light for
most areas with the exception of along the coast. The combination
of the snow and winds pushing in with the front will bring blowing
snow conditions to the coast around the Kuskokwim Delta tonight
into Thursday morning. Light snow will then continue to push
inland into the weekend.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS...
The main feature for the Bering and Aleutians is the low that is
in the southern Bering and tracking north. This low will move
near the Pribilof Islands tonight and then move towards Bristol
Bay through Friday. Initially, the front associated with this low
will bring snow, winds, and blowing snow to the Pribilof Islands
and Eastern Aleutians as it moves through today into tonight. Then
as the low pushes off to the east winds and more snow on the
backside of the low will bring more blowing snow to the Pribilof
Islands tomorrow into Friday and eventually the Eastern Aleutians
as well. However, snowfall for these locations will be limited and
visibility restrictions due to blowing snow that would merit a
blowing snow advisory are not expected at this time.

&&

.LONG TERM FORECAST (Days 3 through 7)...
Beginning the extended period forecast Thursday evening, a
compact and strong low over the Bering Sea will be moving into the
Southwest mainland while shortwave ridging ahead of it moves over
Southcentral. Bitter cold temperatures will begin to give way
toward moderating temps (although still cold) as clouds and
moisture associated with the Bering spread over Southern Alaska.
Snow will move into Southwest Alaska through Friday with the low
then stalling and weakening as it moves toward Southcentral. This
will introduce snow chances for Southcentral although no
significant precipitation will come out of this pattern given the
weakening nature of the low and poor moisture availability. By
Sunday and Monday will see temperatures moderating back close to
normal as the deep polar air mass retreats and a North Pacific low
moves toward the Gulf of Alaska. All global models are depicting a
similar pattern by midweek with a brad trough over the Bering and
southerly 500 hpa flow across the mainland. This will bring
temperatures to, if not above, normal for Southcentral with
precipitation largely favoring coastal areas.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Wind Chill Advisory 145.
         Blowing Snow Advisory 131.
MARINE...Gale Warning 120 127 128 130 131 132 165 170 173 174 181
            185 351 352 413 414.
         Heavy Freezing Spray Warning 121 126 127 128 129 130 131
            139 141 150 160 165 179 180 185 411 412 414.
         Storm Warning 179 412.
&&

$$

SYNOPSIS AND MODEL DISCUSSION...JER
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...DK
LONG TERM...JA



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