Area Forecast Discussion
Issued by NWS Anchorage, AK

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FXAK68 PAFC 250035
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
335 PM AKST Fri Feb 24 2017

.ANALYSIS AND UPPER LEVELS...
Satellite imagery this afternoon shows a continuation of the
active weather pattern. A northwest Pacific low is strengthening
as it tracks northeastward into the western Bering. A storm force
front associated with the low extends from the northwest Bering
southward over the western Aleutians and into the Pacific. The
front is transporting a slug of moist subtropical air northward to
the central and western Bering. A weak ridge is over Southwest
Alaska, bringing a brief respite from a slew of recent frontal
systems and precipitation. Downstream...a weakening front extends
from the Interior southwestward along Cook Inlet and into the
Pacific Ocean. This is bringing yet another round of precipitation
to Southcentral. The Mat-Su Valley is seeing snow out of the
system, however precipitation in the Anchorage area is falling as
a mix of freezing rain and snow.

&&

.MODEL DISCUSSION...
Models are in good synoptic agreement through the short term. The
precipitation over Anchorage and the Matanuska Valley will taper
off in the evening hours and end overnight. There is a bit of
uncertainty regarding the next snow potential Saturday night, with
the biggest uncertainty existing over the Matanuska Valley.
However, significant snow accumulation is not expected at this
point and any impacts of additional light snow over the weekend
would be minimal.

&&

.AVIATION...
PANC...MVFR ceiling due to lingering stratus will likely persist
through Saturday morning.

&&
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
The upper level trough over southern Alaska will move east into
Canada by late this evening. Precipitation will taper off and then
end overnight. Clouds may hang out a little longer in many areas
as the lower atmosphere remains moist. Upper level ridging will
then move into the area for Saturday. The next system will move
into the area Saturday night and Sunday. The flow aloft with this
system will be from the west, and this will limit precipitation
chances as the flow down-slopes off the Alaska and Aleutian
ranges.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
Above freezing Temperatures will peak late this afternoon before
dropping to near to below freezing temperatures tonight, as the
warm front drifts further eastward over the Alaska range and
ridging builds in over the Southwest Mainland. As a result of the
front pushing further eastward, the mixed precipitation from
earlier today has nearly halted over the Bristol Bay area. Patchy
fog is also expected to persist over parts of the Kuskokwim Delta
and Bristol Bay area, with persistent onshore flow and ample
moisture being trapped near the surface. A second warm front push
onshore Saturday morning bringing another round of warm/moist air
and mixed precipitation to parts of the Southwest Mainland. Mixed
precipitation will begin to transition back to snow Sunday into
Monday, as colder Northwesterly flow begins work its way back over
the mainland.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
A series of fronts will bring gale to storm force winds with a
mixture of snow and rain to the Bering and western Aleutians into
the weekend. High pressure building over the western Aleutians and
Bering Sunday afternoon will then spread colder air over the area
from the North and West, as winds begin to diminish through Sunday.

&&

.LONG TERM FORECAST (Days 3 through 7)...
A colder pattern slowly settles back over the southern mainland
and surrounding waters for next week. The upper level ridge
building over the mainland this weekend, flattens out on Monday as
a strong shortwave dives from the Arctic bringing a colder air
mass to the Gulf. A new ridge quickly develops over the Bering
into Tuesday with a long wave trough stretching along the mainland
and Gulf. Models are in relatively good agreement with this
weather regime, however they differ slightly on handling multiple
waves that eject southward from the Arctic. Only minor changes
were made in the extended forecast due to uncertainty in both
timing and placement of the anticipated waves.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...None.
MARINE...Storm Warning 177 178 185.
         Gale Warning 120 130 131 170 173 175 176 179 180 181.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...RD
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...PEPE
LONG TERM...KH


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