Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 230017
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
417 PM AKDT SUN MAY 22 2016
.ANALYSIS AND UPPER LEVELS...
A well-developed upper level trough is currently stretched across
the Kuskokwim delta and is associated with an upper low in
eastern Russia. At the surface, a weak low is centered over the
Kuskokwim delta with an associated front that stretches into
Bristol Bay. As a result, rainfall and widespread cloud cover
encompasses the Bristol Bay and Kuskokwim delta and Kuskokwim
valley. To the east, mainly clear skies are occurring beneath a
broad ridge that stretches from the gulf of alaska into the
eastern Alaska mainland. Clouds are beginning to enter western
portions of south central this afternoon as the upper level
trough pushes east.
Models are in fairly good agreement today as the upper level wave
currently centered over the southwest mainland pushes across
Anchorage quickly overnight. Models differ slightly in
precipitation amounts, with the nam indicating overall less
rainfall. As a result a blend of models was chosen today.
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Wet conditions will return to most of south central Alaska as a
front pushes into the region overnight. Most of the rainfall will
be over inland portions of the area from the Anchorage Bowl
northward with only scattered showers expected over portions of
the Kenai Peninsula and the Gulf Coast. In the wake of the front
on Monday afternoon and Tuesday, showers will remain in the
forecast mostly along the mountains of the Susitna Valley and the
Copper River Basin. Winds will switch to a westerly to
northwesterly flow behind the front, which will help to bring
generally clear skies and drier conditions over the western half
of the area by Tuesday. Winds will increase through some channeled
areas such as Seward and Portage Valley with the northwesterly
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
An upper level shortwave will track through the southwest Alaska
region this evening before exiting the area by early Monday
morning. This will bring continued stratiform rain before tapering
off by Monday morning. Then a ridge of high pressure will move
into the region briefly before an upstream trough moves into the
Kuskokwim Delta by Monday afternoon. This synoptic feature will
move into the lower Kuskokwim Valley and the Bristol Bay interior
by Monday evening before crossing the Aleutian Range by Tuesday
morning. Look for increased possibility of marine layer stratus
with the onshore flow and patchy fog through Tuesday.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
The Bering Sea and the Aleutians will continue with a
southwesterly flow through Tuesday. As an upper level shortwave
moves from west to east through the area before moving inland
into southwest Alaska by Monday afternoon. This will produce a
scattered showery regime before an upstream ridge moves into the
Bering Sea by Monday evening. This will increase the chances for
patchy to areas of fog along the eastern Bering Sea with this
ridge building into the area. By early Tuesday morning a weather
front will enter the western Aleutians. This will bring gale
force southerly winds by Tuesday morning into the western
Aleutians before diminishing to Small Craft Advisory winds by
Tuesday afternoon as the system weakens.
.LONG TERM FORECAST (Days 3 through 7)...
The South central mainland, and the southwest Alaska regions will
have drier conditions as high pressure builds into the region by
Tuesday afternoon through Thursday morning. While the northern
Gulf of Alaska will have a weak low by Tuesday resulting in
moisture along the coastal communities before tracking to the
lower southwestern Gulf by Thursday. Then an upper level
shortwave drops down from the north, and tracks along the Alaska
Range before a secondary shortwave digs farther south into the
base of the trough over the Southwest Alaska region by Thursday
morning. This synoptic feature will develop into a closed low
along the Alaska Peninsula by Saturday. Therefore, the southwest
Alaska region, Gulf of Alaska, and the northern coastal
communities will see slightly cooler temperatures with increased
cloud cover going into next weekend. On the Bering Sea side, they
will be under the influence of an amplified ridge of high pressure
heading into the midweek. This synoptic feature will gradually
move eastward before developing into a strong closed high pressure
over the eastern Aleutians by Thursday. This upper level closed
high will further strengthen, extend through the western Bering
Sea into the eastern Siberian region heading into next weekend.
Look for marine layer stratus and fog to develop throughout next
week for the Bering Sea, and the Aleutians. This high pressure
will keep systems out of the Bering Sea except for the western
Aleutians being affected slightly as system track by into the
northern Pacific Ocean. The forecast confidence remains average
as the models have become better aligned for next week.
MARINE...Gale Warning 120 130 131 139.
SYNOPSIS AND MODEL DISCUSSION...en
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...pd