Heavy Freezing Spray Warning 55, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
410 AM AKST Fri Feb 5 2021

.ANALYSIS AND UPPER LEVELS...

An upper level ridge stretches north over the western Alaska coast
into the Chukchi Sea and east across the mainland into Canada. An
upper level low near the Kamchatka Peninsula has a trough stretching
southeast across the Bering Sea.

At the surface, an area of weakening low pressure remains south of
Prince William Sound. A ridge stretches south into Southcentral,
with stratus and fog stretching across Cook Inlet, the Knik Arm
and Turnagain Arm.

Heavier snow and blowing snow continue across the Kuskokwim Delta
coast this morning with strong winds across the area. Light snow
showers are seen on radar across the Kuskokwim Delta with rain
across the eastern Aleutians and snow across the western Aleutians
seen on observations. Small craft winds and waves are occurring
over most of the Bering and the Aleutians.

&&

.MODEL DISCUSSION...

Models remain in fairly good agreement on synoptic features
through the next several days. Smaller scale details, including
a shortwave approaching Southcentral, are a little harder to
refine.

&&

.AVIATION...

PANC...MVFR and IFR conditions are expected through the morning with
low stratus and fog across the Inlet. Winds will remain light and
out of the north.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...

Friday is beginning with clear skies over a large portion of
Southcentral except for Kodiak, where the next front is moving
clouds into the region, and Cook Inlet with the persistent
stratus. This stratus around Cook Inlet should continue to clear
out from the north, but will still hang around for longer right
along the western edge of the Chugach and Kenai mountains due to
the slight orographic lift in the north to northwest flow. This
too should dissipate later this morning as the front moves into
the region.

The potential for snow is just a quick shot right as the front
moves across the region. For Anchorage, this means early this
evening. Cook Inlet may still see some pesky stratus again after
this front so not expecting it to really clear out over Anchorage
and the Cook Inlet region until Sunday. This is also the case for
the Copper River Basin. Other areas of Southcentral should see
clearing skies on Saturday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3)...

A frontal system that brought some light snow and blowing snow to
the Kuskokwim Delta Coast this morning is pushing inland. As a
result, the Winter Weather Advisory previously in effect has been
cancelled early due to rapidly improving conditions behind it.
The frontal system will continue pushing inland bringing
practically all of Southwest some snow with a general 0.5 to 2.5
inches of snow for Bristol Bay and the Middle Kuskokwim Delta.
Also, as the main upper trough lifts through the area before the
upper ridge builds in, there may be increased snow shower activity
for the Kuskokwim Delta this evening into the overnight hours.

An upper level ridge will build in behind this front bringing
quieter and colder conditions to Southwest for Saturday through
Sunday night. Much of the area is expected to see sunshine on
Saturday and Sunday, though, the next frontal system will begin
to encroach on the coastal areas of the Kuskokwim Delta coast as
early as Sunday afternoon with the potential for some more light
snow. It is still too early to tell but latest indications show
warmer air is expected to move into the immediate coastal regions
with this next front potentially causing precipitation type
issues. Just how much warm air and how quickly it warms up still
remains somewhat uncertain at this time. As this front approaches
on Sunday, winds will begin to ramp up for the coastal regions of
Southwest. Lastly, fog/low stratus may be a concern for areas
tonight into Saturday morning as this ridge builds overhead and
some lingering moisture may remain. At this time, it was left out
of this forecast package.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3)...

An upper level shortwave which can be seen on nighttime
microphysics this morning near Adak (currently snowing there) and
surrounding areas will continue moving eastward. This upper level
shortwave is expected to bring some light snow with reduced
visibility for a time to the Pribilofs. Other than that, much of
the central and eastern Bering Sea will remain quiet today with a
good amount of sunshine for the eastern and central Aleutian
Chain.

The next big weather maker will be a storm system currently taking
shape over the North Pacific south of the western Aleutians. This
storm system will move northward today while strengthening and
send a storm force front through the western Aleutians this
afternoon into this evening along with increased wave heights up
to 30 ft especially on the Pacific side Saturday afternoon. Storm
force winds diminish with this system overnight with mainly gales
across much of the Bering. This front continues to move slowly
eastward merging with a piece of energy moving northward toward
Dutch Harbor which will bring unsettled weather conditions in the
form of rain for Saturday as a good amount of warm air comes
northward with this system. Conditions remain unsettled for much
of the Bering and Aleutian Chain through Sunday.

Another storm system is expected to follow on the heels of the
aforementioned one beginning to impact the western Aleutian Chain
Sunday afternoon with gale force winds and more unsettled
conditions.

&&

.MARINE (Days 3 through 5: Sunday through Tuesday)...

Gulf of Alaska: A low exits the southeast Gulf Sunday. Model
tracks are similar, and confidence is good through Tuesday.
Lingering gusty winds through the lower Shelikof Strait and
Sitkinak areas, and across the southeast Gulf, both areas
diminish late Sunday. A weak trough forms over the Northern Gulf
with variable winds through Tuesday. Wave heights to 8 feet
across the Southern Gulf, subsiding.

Bering Sea: A well developed low and front sweep into the
northern Bering for Monday. This wind wrapped low and front
continues widespread small craft winds and waves with high end
gale force gusts through Tuesday. Wave heights to 24 feet over
the northern Bering, subsiding Monday. Model features become
mixed, so confidence is decreasing with a new North Pacific low
and front that pushes into the central Aleutians and Bering by
Tuesday. Widespread high end gale force winds with the front into
the central Aleutians and Bering while the low tracks near the
western Aleutians with its wind field through Tuesday. Wave
heights to 27 feet on the Pacific side, 24 feet on the Bering side
through Tuesday.

&&

.LONG TERM FORECAST (Days 4 through 7: Monday through
Thursday)...

The long term forecast begins with the deepening of a polar
trough sliding south of the AL-Can border late Sunday. By Monday,
this feature transitions to a closed low situated over the
interior of the state. Temperatures at 850mb are expected to drop
around -35C in the core of the arctic airmass as another round of
very cold air settles across the region. Expect clear and cold
conditions across most of Southcentral and Southwest Alaska
through midweek with daytime high temperatures struggling to reach
zero degrees over the Copper River Basin, single digits and teens
from the Susitna Valley south along Cook Inlet, and 20s along the
immediate coast. Similar temperature ranges are also expected
from interior Southwest to the Southwest coast and AKPEN. Along
with the colder temperatures, northerly outflow winds will
develop, with the strongest of these winds through the favored
mountain gaps as well as through bay and passes along the
immediate coast.

By late Tuesday into Wednesday, the upper-level low is expected to
continue to drift westward. This would allow a southerly flow to
develop from east to west across Southcentral, bringing moisture
associated with a trough in the Gulf northward. Light snow will be
possible from the Kenai Peninsula north and east across Prince
William Sound and the Copper River Basin Wednesday into Thursday
as the coldest of the arctic air retreats to the northwest.

Farther west, a ridge is expected to build across the eastern
Bering while an upper-level trough persists over the western
Bering. An active weather pattern will continue through midweek
over the western Bering and Aleutians as a series of surface lows
lift over the region from the North Pacific.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Storms: 176 177 178 411.
		 Gales: 120 130 131 155 165 170 171 172 173 174 175 179
			    181 185 351 352 412 413 414.
	     Heavy Freezing Spray: 180 185.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...CRK
SOUTHCENTRAL ALASKA...EZ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MV
MARINE/LONG TERM...MK/TM