Gale Warning 55, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
533 AM AKST Sat Jan 8 2022

.ANALYSIS AND UPPER LEVELS...

At 500 mb there is a strong high over Siberia that extends to the
Alaska Peninsula and a polar vortex over Canada with a trough
axis extending to the Kenai Peninsula. There are major shortwaves
south of Attu and Dutch Harbor. On nighttime microphysics
satellite imagery an area of low stratus is discernible over
portions of Turnagain Arm. Also on satellite imagery, there is an
occlusion south of Adak and Dutch Harbor with the warm front over
the northeast Pacific. The jet is north-south oriented and it
spans from Kotzebue to the Alaska Range and the Cook Inlet. The
jet core has a magnitude of 85 knots. The high for the state was
43F at Dutch Harbor.

&&

.MODEL DISCUSSION...

The NAM and GFS models initialized well over the Bering, Pacific
and mainland Alaska. The models are in good agreement with the
synoptic pattern through Monday. The run to run continuity has
improved with the models.

&&

.AVIATION...

PANC...The past 3 mornings, fog/low stratus has been detected
over portions of Turnagain Arm. This morning there is low stratus
again over Turnagain Arm. The expectation is that the low stratus/fog
will stay south of PANC. Winds at PANC will be northerly this TAF
package with gusts as high as 20 knots later this afternoon.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3...Sat
through Mon)...A weak, low-level shortwave is passing through
Prince William Sound this morning. Models did not resolve this
feature well yesterday and have only caught onto it in earnest
overnight. It looks stronger than indicated yesterday with better
lift and more moisture. Thus, we have increased PoPs and snow
amounts from Whittier, through Turnagain Pass, and down into
Seward. While there is some indication that light snow may even
make it as far another as Anchorage early this afternoon, any
amounts should be extremely minimal with all the dry air in place.
Persistent onshore flow for Kodiak City will allow for off and on
snow showers through the day today. As this shortwave arrives
later tonight, it will serve to reinforce the moisture and onshore
flow resulting in some minor accumulation possibly.

Attention then shifts to a much stronger area of low pressure over
the North Pacific early Sunday. This system races north into the
Gulf by Sunday afternoon bringing another round of storm force
winds to many marine areas. It will also serve to once again
tighten the offshore gradient. This will once again increase winds in
the typical gaps such as Thompson Pass and the Matanuska Valley.
While the precipitation field with this system looks impressive,
it will remain primarily confined to coastal locations. As the
snow arrives in Kodiak, Whittier, and Thompson Pass, expect the
combination of cold air, winds, and falling snow to reduce
visibility. The worst of this looks to impact Thompson Pass Sunday
evening. A Winter Storm Watch has been issued to address this
concern. As the system pushes closer to Prince William Sound,
heavy snow will be possible for Portage Valley and Turnagain Pass.
1-2 feet of snow will be possible for these areas by late Monday.
Any motorists planning to travel the Seward Highway should stay
apprised of the forecast.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Day 1 through 3: Today
through Mon night)...

Dry, windy conditions, and Arctic air is expected to remain over
Southwest Alaska today. Any storms are expected to remain well
south of the area as very strong high pressure across the Alaska
interior keeps the storm track across the southern Bering Sea and
Aleutian Chain. An upper level shortwave is expected to cross the
Alaska Range later this morning and move across Southwest Alaska
this afternoon through tonight. This will aid in keeping the gusty
northeasterly winds going throughout the day and through tonight
as Arctic air gets reinforced across the area. There is the slight
chance for a few light snow showers for Bristol Bay this
afternoon and especially during the overnight as the shortwave
passes through, though, the air will be very dry in the low levels
resulting in potentially just a virga scenario with no precipitation
actually reaching the ground. Some models show this activity
extending into the Kuskokwim Delta and the Lower Kuskokwim Valley
also but thinking the dry air in place will win out resulting in
some clouds at best. Also, a tight pressure gradient across the
area will also aid in keeping the gusty winds throughout Southwest
today through Sunday with sustained northeasterly to northerly
winds of 20 to 30 mph with gusts as high as 40 mph with perhaps a
few gusts to 45 mph especially along the immediate Kuskokwim Delta
Coastline. Therefore, wind chills this evening through Sunday
afternoon may reach as low as 35 below zero at times. Make sure to
bundle up when venturing outdoors especially this evening through
Sunday afternoon.

One change to the forecast this morning is that the system
originally expected to arrive on Sunday has slowed down some as
well as looking like most of the moisture with it will remain on
the east side of the Aleutian/Alaska Range. Therefore, this
forecast package reflects this change. One last note on this
system is that there may be a period of storm force winds for the
coastal marine waters south of the Alaska Peninsula on Sunday
morning.

Overall, expect another breezy/windy day on Sunday for much of
Southwest with winds diminishing Sunday night. Some very light
precipitation in the form of light snow showers may overspread the
Bristol Bay area during the day on Monday with the Kuskokwim
Delta and Lower Kuskokwim Valley remaining mostly dry. A more
rigorous shortwave approaches the area from the southeast Monday
evening through Mon night that may result in more widespread snow
shower activity as this wave will have a little more moisture to
work with.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Day 1 through 3:
Today through Mon night)...

Northeasterly flow is expected to dominate across much of the
Bering throughout the weekend and into early next week keeping
storms south over the North Pacific or moving northward into the
Gulf of Alaska. The current storm system south of the Aleutian
Chain is expected to mostly meander in place for the next couple
days with just its front impacting the coastal marine waters and
the Aleutian Island Chain. Expect occasional periods of
precipitation of rain and snow over the course of the weekend as
this low will keep the area unsettled. Also, expect gale force
winds with the coverage of gale force winds expanding throughout
the day across much of the Bering Sea. Due to the northeasterly
flow and air flowing off of the ice edge and over the open
relatively warm water of the rest of the Bering Sea, there is the
potential for cloud streets to form with occasional snow showers
that may impact the Aleutian Chain for places such as Adak and
Shemya at times for the next couple of days. Dutch Harbor is
mostly expected to have rain but some snow mixing in cannot be
ruled out. Heavy Freezing Spray makes a return today as well to
much of the Bering Sea as Arctic air flows off the ice and over
the open water. Heavy freezing spray will remain a concern through
the weekend and into early next week along with increased wave
heights.

&&

.MARINE (Days 3 through 5 - Monday through Wednesday)...

Gulf of Alaska: A well developed low near Kodiak Island moves
into Southwest Alaska and dissipates for Tuesday. Its front
extends across the North Gulf Coast through Wednesday. Forecast
confidence is fair with the frontal development. Widespread gusty
winds with areas of gales over the Northern Gulf and Cook Inlet.
diminishes late Monday. Seas to 24 feet across the Northern Gulf,
subsiding Tuesday.Slight risk of freezing spray over Cook Inlet
Monday.

Bering Sea: High pressure retreats over the Russian Far East
through Wednesday. A well developed North Pacific low moves over
the Central Aleutians through Wednesday. Forecast confidence is
fair with the low track and timing. Widespread gusty winds with
areas of gales over the Bering and Central Aleutians diminishes
Wednesday. Seas to 18 feet, subsiding Tuesday. Slight risk for
freezing spray over Western Bering open waters.

&&

.LONG TERM FORECAST (Days 4 through 7/Tuesday through Friday)...

Upper level ridging over the Mainland tracks southwestward as
upper level troughing digs down across the state, extending into
the Bering Sea. Simultaneously, a system over the Aleutians pushes
its front into the Gulf, generating periods of significant
precipitation, namely along the North Gulf Coast and Kodiak
Island, mid-week. Winds may pick up as pressure gradients tighten,
especially through bays and passes such as Resurrection Bay and
Passage Canal. A North Pacific low moves towards the AKPen towards
the end of the week, its front pushing the northern Gulf by
Thursday. Periods of heavy rain or snow are possible along the
North Gulf Coast, with lighter precipitation possible elsewhere
across Southern Alaska as we approach the weekend. The orientation
of the trough as it pushes onshore may allow for downsloping to
occur over western Anchorage and western Kenai.

&&

.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...131 Wind Chill Advisory/Winter Storm Watch.
MARINE...Storm 150 120 130 131 132 138.
Gale 155 165 170 172 173 174 175 176 177 179 180 181 185 411 412
413 414 351 352 119 127 128 136 137 139
Heavy Freezing Spray 165 179 185 412 414 119 126 127 128 130 139
141.
FIRE WEATHER...NONE.

&&

SYNOPSIS AND MODEL DISCUSSION...PJS
SOUTHCENTRAL ALASKA...MO
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MV
MARINE/LONG TERM...KM/KM