Small Craft Advisory 111, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
450 PM AKST Sat Feb 3 2024

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3:
Tonight through Tuesday)...

Active weather and warmer temperatures are returning to
Southcentral as an upper-level trough and associated surface front
track across the region from the southwest. A surface low will
develop just off of the northern end of Kodiak Island and then
move up along the eastern Kenai coast, reaching the Prince William
Sound area on Sunday afternoon.

As such, precipitation reached Kodiak Island this morning and
Kenai Peninsula/Cook Inlet this afternoon. Akhiok reported rain,
otherwise precipitation remains mostly snow with this system. Snow
will continue to spread north to Anchorage later this afternoon
and then the rest of Southcentral tonight. Northerly winds will
continue to increase across the western Kenai Peninsula, Cook
Inlet, and west Anchorage through Sunday. Since the snow is
expected to be very fluffy and low-density, the potential remains
high for areas of reduced visibility due to blowing and drifting
snow. Thus, a Winter Weather Advisory remains in effect today
through Sunday for snow and blowing snow for the western Kenai
Peninsula and Anchorage Bowl. Thompson Pass is another location
that can expect to see several inches of snow and blowing snow. A
Winter Weather Advisory for Thompson Pass will begin tonight.

With the newly formed surface low tracking north towards Prince
William Sound, the eastern Kenai and Prince William Sound will
continue seeing snow spread to the north. Snowfall will increase
by Sunday morning as the surface low approaches and then begins to
weaken later Sunday.

Another system will quickly follow on the heels of the
aforementioned system, bringing another round of snow that will
spread north through the day Monday. The NAM still keeps the
surface low tracking along the Southcentral coast while the GFS
develops a low that takes a more easterly track out towards the
central Gulf. By the end of Tuesday night, yet another front
approaches the western Gulf. In conclusion, expect continued
active weather for Southcentral for the next several days.

AF/PP

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS (Days
1 through 3: Tonight through Tuesday)...

Key Points:

* A series of storms moves in through Monday, leading to active
  weather and a gradual warming trend.

* Blizzard Warnings are in effect through Sunday morning for the
  Kuskokwim Delta, as well as Bristol Bay north and west of
  Dillingham.

* A High Wind Watch has been issued for the Central Aleutians from
  Sunday evening through Monday morning.

Discussion:

A broad low over the central Bering Sea is producing blizzard
conditions across portions of the Kuskokwim Delta and Bristol Bay
as its front pushes into Southwest Alaska this evening. The worst
conditions are occurring along the coast and within locations of
favored gap winds. An additional area of note experiencing less
than one quarter mile visibility is north and west of Bethel,
including the communities of Nunapitchuk and Kasigluk, where
strong winds gusting to 45 mph and falling snow are producing
whiteout conditions. The front moves inland through tonight, with
winds gradually decreasing and visibility expected to gradually
improve. Snow also comes to an end from south to north as the back
edge of the front passes through overnight. By Sunday morning,
the threat of low visibility due to blowing snow largely comes to
an end. Near the center of the low, the Pribilof Islands, as well
as the central and eastern Aleutians, are experiencing a mix of
rain and snow showers. The low center tracks into the northern
Bering by tonight, bringing continued snow shower activity into
Southwest Alaska behind the front.

Also on Sunday morning, a storm force North Pacific low begins to
push into the central Aleutians. Its front pushes across the
Aleutian Chain, bringing a mix of rain and snow along with
easterly gales. The main concern, however, will be as the low
tracks into the central Bering on Sunday night. Cold air
advection on the south side of the low will allow for winds in
excess of 65 kt aloft to mix down to the surface as gusts. The
wind swath passes through the central Aleutians Sunday evening
into Monday morning, leading to a moderate potential for high wind
gusts (at least 75 mph) in Atka, where the highest confidence is
for the strongest winds to occur. However, some uncertainty in
track of the low means there is a low potential for high winds to
also occur in Adak, if the track shifts west, or Nikolski, if the
track shifts east.

The low's front pushes into Southwest Alaska Sunday night, leading
to another round of snow and blowing snow for the Southwest
Coast. This front looks similar in nature to the current front
pushing through the area this evening. The main difference between
fronts will be air temperature, which looks to warm into the 20s
to near 30 degrees by Sunday night. The amount of warming, for
which there is a large model spread and low confidence, is likely
to impact the degree to which blowing snow will be an issue. As
the temperature forecast becomes clearer, confidence on the
potential impacts will likely increase as well. For now, it
appears this front may warrant another round of winter weather
products with visibilities decreasing to one half mile at times.
Another round of blizzard conditions cannot be ruled out either,
especially if temperatures remain on the lower end of the spread.

For Monday, the low occludes and weakens, with the front pushing
into the Interior. Expect widespread rain and snow showers across
the domain. Looking ahead to Tuesday, yet another North Pacific
low makes its way towards the Alaska Peninsula and Southwest
Alaska, bringing another round of precipitation.

CQ

&&
.LONG TERM FORECAST (Days 4 through 7: Wednesday through Saturday)...

A broad upper level low centered over the Bering Sea moves north
into Chukotka on Wednesday. It elongates, extending a trough
across the Alaska Peninsula and into the Gulf. This delivers gale
force winds across the Bering, and snowy weather across Southwest
Alaska through Thursday. Friday morning a North Pacific low south
of Kodiak Island spreads gale force wind northward across the
Gulf, and brings snow to the northern Gulf coast.

&&

.AVIATION...

PANC...Snow is expected to overspread the area from this evening
through the first half of Sunday. Snow intensity will generally
remain on the light side, but visibilities issues are expected as
snow consistency will be dry/fluffy. Despite forecast winds 8 to
12 kts, this snow may become or remain suspended, resulting in
IFR vis at times overnight and tomorrow morning. Snow rates and
any vis issues are expected to peak Tuesday morning. Gradual
improvement is then expected over the course of Sunday.

-Brown

&&