Small Craft Advisory 52, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
459 PM AKST Wed Jan 15 2025

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

An elongated upper level trough and associated surface low
continue to weaken over the western Kenai Peninsula, with a
lingering band of light to locally moderate snow near Nikiski
through Kenai and Soldotna this afternoon. Precipitation will
quickly diminish through this evening. Gusty northerly gap winds
peaking around or shortly after midnight, before diminishing
through the day on Thursday.

An upper level ridge begins to build over Southcentral from the
southwest by Thursday morning. This should bring clearing skies
for tonight and Thursday for inland areas. However, this ridge
will amplify as it moves to the AlCan border on Friday which will
bring in southerly flow aloft and warming temperatures for Friday
and into the weekend. Light precipitation will begin to overspread
Kodiak Island early Friday morning and the eastern Kenai
Peninsula and western Prince William sound by late Friday
afternoon. At least initially on Friday, the antecedent cold air
mass will lead to light snow for the coastal mountains before
heavier precipitation moves in with warmer, southerly flow late
into the weekend. Snow levels are expected to raise to near 1000
ft by Friday afternoon, reaching as high as 1500 ft this weekend.
Inland areas, including Anchorage, should remained downsloped and
dry through at least Saturday.

A North Pacific low moves into the Gulf for Saturday night into
Sunday bringing another round of relatively heavier precipitation
and elevated winds to the coast.

-ME

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING SEA/ALEUTIANS
(Days 1 through 3: This afternoon through Saturday afternoon)...

Generally stormy weather persists as two lows and their front
move across the region from now through the weekend. Two new
advisories are in effect for Kuskokwim Delta:
* Winter Weather Advisory for blowing snow for Nunivak Island and
  most of Kuskokwim Delta, from Thursday afternoon through Friday
  morning
* Coastal Flood Advisory for Kwigillingok and Kongiganak, from
  Thursday night through Saturday afternoon

A broad low moving from the North Pacific into the Bering Sea will
push its front east and north across the Bering Sea and into
Southwest Alaska. Expect gales along the front, with gusts as high
as 40-50 mph, and light to moderate precipitation. There is some
uncertainty with how quickly temperatures will warm above
freezing and, therefore, how much precipitation will fall as snow.
Generally, snow amounts will top out at around 4 inches, with
greater snow amounts along Kuskokwim Delta, where colder
temperatures are expected to hold out for longer. This is also
where the Winter Weather Advisory is in effect, as gusty winds and
falling snow could lead to significant visibility reductions
before warmer air turns precipitation into rain/snow mix or all
rain by Friday morning. There is a chance for parts of Bristol
Bay, especially from Togiak/Twin Hills to the Western Capes, to
see visibility reductions and blowing snow with this storm, but
confidence is lower.

Aside from the Winter Weather Advisory, a Coastal Flood Advisory
is also in effect for parts of Kuskokwim Delta, specifically
Kwigillingok and Kongiganak. Onshore, southeasterly flow, similar
to past flood events, could bring a return of floodwaters. The
minor upside is that the moon is beginning to wane, so tides
shouldn't be as high as they were for the flood events earlier
this week. Still, all this warmer air will likely lead to melting
sea ice, which may leave the coastline more exposed. The Coastal
Flood Advisory encompasses both the first storm (Thursday evening
through Friday morning) as well as a second storm that looks to
arrive some time between Friday afternoon and Saturday afternoon.
This second storm has a lot more timing uncertainty associated
with it. Models generally agree with the strength and general
track of the feature (~975 mb low with gale force winds), but the
timing varies as much as 6-12 hours. Generally, this forecast
package leaned towards a faster solution with stronger winds. If
the alternate scenarios play out, we could see the timing of
strong winds and any coastal flooding delayed by 6-12 hours, or
weaker wind speeds and less severe coastal flooding. Overall, stay
tuned as we continue to assess these differences and refine the
forecast.

-Chen

&&

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

On the Alaska Weather map, an elongated upper level trough
extends from Siberia across the Bering and Aleutians. Several
moderately strong shortwaves out of Russia and the North Pacific
rotate through the active high amplitude pattern, and flattens the
downstream ridge over Interior Alaska on Monday. The shortwave
effects from the North Pacific forms closed lows over the
Aleutians through Tuesday. The ridge regains its footing from
Southeast Alaska across the Mainland by midweek. Even with all the
flexing of the windflow pattern, significant surface weather
features affect the Southcentral and Alaska Peninsula in sustained
onshore flow through most of the forecast period.

The weekend closes out with areas of rain mixed with snow or snow
leading across Southwest Alaska through Monday. A decaying
surface low spreading locally heavy rains over parts of Kodiak
Island, Kamishak Bay and the Kenai Peninsula. These heavy rains
diminish as the low progresses Northeastward over Prince William
Sound late Monday. Right on its heels, a series of weak North
Pacific lows and fronts marches across the Aleutians and Alaska
Peninsula Tuesday. Gusty winds push over the Western Aleutians
through Monday, while gale force winds approach the AKPEN coasts
and Kodiak Island Tuesday. Gale force winds develop ahead of
another front approaching the Western Aleutians late Tuesday into
Wednesday. A third low follows suit with widespread rain and gusty
winds from the Eastern Aleutians to Prince William Sound through
Wednesday.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. Cloud cover is
likely to stick around through tomorrow. Some lower clouds may
move in late tonight but conditions should stay VFR. Winds switch
around to south-southeasterly tonight and will shift back to
northerly by Thursday morning.

&&