Small Craft Advisory 73, NWS Anchorage, AK

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
500 AM AKST Thu Jan 23 2025

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

An upper-level trough and attendant occluded front are quickly
racing from Southwest Alaska eastward toward Southcentral this
morning. Precipitation is filling in on radar from Kodiak Island
northeast to eastern Prince William Sound and the Susitna Valley.
As of 4 AM, much of the precipitation has yet to reach the ground,
thanks to a layer of drier air near the surface. However, as the
column saturates, expect a mix of rain and snow to develop with
temperatures across the region hovering between 28 and 36 degrees.
Most locations will see primarily rain with this system. However,
snow is expected at elevation and across the northern half of
Susitna Valley where colder air remains in place.

A Winter Weather Advisory remains in effect for northern Susitna
Valley as today's storms will bring heavy snow, on the order of
8-12 inches north and west of Talkeetna and 1-3 inches for
Talkeetna, to the region. Otherwise, this will truly be the calm
before the storm as a warm and incredibly wet series of
atmospheric rivers sets its sights on Southcentral. A Hydrologic
Outlook has also been issued for the Kenai Peninsula, Anchorage,
and Mat-Su in anticipation that temperatures in the high 30s/low
40s and prolonged, moderate to heavy precipitation could lead to
flooding. We will be closely monitoring this storm system, and we
urge you to stay tuned to the forecast and prepare accordingly.

The showers this morning across the Cook Inlet area will taper off
for a time this afternoon. However, a trailing upper-level trough
will slide across the region later tonight, allowing for another
round of showers to develop from Homer north to Palmer. For
upslope locations (eg. northern Susitna Valley and coastal
mountains), this wave will help to enhance the precipitation,
brining a second round of heavier rain and higher elevation snow.
This system, exits the region by early Friday morning.
Precipitation is expected to taper off again, but a southerly
flow aloft will keep upslope rain/snow showers persisting for the
aforementioned locations.

Looking ahead, Friday morning through Sunday continue to be when
the most impactful weather is expected. As mentioned above, we're
anticipating a trend towards warmer and much wetter conditions,
with the potential for moderate to heavy precipitation to persist
through most of the weekend. All but deep interior Copper River
Basin will likely see precipitation at some point. It's a bit
early right now to give detailed precipitation estimates, but
liquid precipitation amounts from Friday through Sunday could be
somewhere in the range of 1-3 inches from Kodiak Island to
interior portions of Southcentral, including Cook Inlet and the
Mat-Su Valleys; 2-4 inches across the Eastern Kenai Peninsula and
Western Prince William Sound; and 3-5 inches across Western Prince
William Sound, including Valdez and Cordova.

Most communities and areas along the road network will likely see
this precipitation falling primarily as rain, with the exception
of higher elevation locations like Broad Pass, Isabel Pass, and
Thompson Pass. In addition, a tightening pressure gradient will
lead to gusty southeasterly winds through Turnagain Arm/Anchorage,
Palmer, and the Copper River Basin. Stay tuned for forecast
updates as we could see fairly impactful weather from Friday into
the weekend.

-TM/Chen

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA AND THE BERING SEA/ALEUTIANS
(Days 1 through 3: Today through Sunday morning )...

A frontal system continues moving inland of Southwest Alaska
towards the Lower Kuskokwim Valley and interior Bristol Bay this
morning. This will bring another round of rain and rain/snow mix
to those areas through the morning hours. Quickly on the heels of
that system, a more significant North Pacific low tracks into the
Bering Sea by this afternoon. A strong push of warm southerly
flow will accompany this system. Also with this system are very
impressive jet dynamics. A southerly jet-streak of about 130 to
140 kt looks to pass over the Eastern Aleutians by this afternoon.
Thus, there is quite a wide swath of sustained storm-force winds
and hurricane-force gusts (in both the North Pacific and Bering)
along the Eastern Aleutians and Southern Alaska Peninsula (AKPEN)
as this system tracks from the North Pacific to the Bering today.

Thus, with the favorable jet dynamics and with the strongest core
of winds passing overhead of the Eastern Aleutians, a High Wind
Warning remains issued there through 10 PM AKST tonight (Thursday
night). In particular, Nikolski and Akutan have the best chance at
seeing a few wind gusts up to 80 mph today through the afternoon
as the strongest winds pass through the area. Unalaska/Dutch
Harbor looks to see gusts between 40 to 60 mph with this system. A
High Wind Warning has also been issued for the Alaska Peninsula
with the potential for favorable channeling of southerly to
southeasterly winds through terrain on the southern AKPEN. Cold
Bay and False Pass have the best chances to see a few gusts to 75
mph today through tonight. In addition to the strong gusty winds,
moderate to heavy rain looks likely to fall along the Eastern
Aleutians today and through the weekend with each system coming
northward to the area. 2 to 3.5 inches of rain could fall between
today through the weekend. The heaviest rain looks to fall today
through this evening. A Special Weather Statement has been issued
for the Eastern Aleutians to bring awareness to the heavy rain
threat.

As the system pulls northward into the Bering through the day
today, southwesterly winds along the Kuskokwim Delta Coast will
turn southerly and strengthen through the afternoon hours. Wind
gusts along the coast look to peak tonight into early Friday
morning with gusts between 50 to 60 mph; especially for
communities like Kwigillingok and Kongiganak. This southerly push
of wind in conjunction with high tide tonight/early Friday morning
could lead to storm surge flooding tonight into Friday morning.
Thus, the Coastal Flood Warning remains in effect along the
Kuskokwim Delta Coast from the mouth of the Kuskokwim River to
Tununak through 9AM AKST Friday.

The active and amplified pattern continues Friday and through the
weekend as yet another North Pacific low lifts northward to the
vicinity of the Eastern Aleutians late Friday night and very
slowly moves eastward to the vicinity of the Southern AKPEN by
Sunday as the system nudges up against a strong Pacific ridge to
its east. This configuration or the North Pacific low near the
Eastern Aleutians and southern AKPEN in conjunction with the
strong amplified Pacific ridge to the east will allow for deep
tropical moisture and warm air to be pulled northward and over
the AKPEN and most of mainland Southwest through the weekend. At
the same time this is happening, cold air will surge south and
west out of eastern Russia and through the Bering starting today
and work eastward to the Pribilof Islands and Nunivak Island by
early Friday morning. At this point, it is hard to say how far
east the cold air will make it through the weekend due to when it
nudges up against the southerly warm air push. There is reasonable
confidence that most snow Friday through Sunday will stay
confined to the Kuskokwim Delta. Stay tuned to the forecast as
more details are fine-tuned with this developing atmospheric river
for the weekend.

&&

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

Key takeaways:

	- High southerly winds and heavy precipitation shifts away from
   the southern coast towards the Panhandle
	- Heavy snow totals across the Brooks Range, Kenai Peninsula and
   higher elevations of South Central will start to taper off
	- Significant pattern shift to bring much colder temperatures
   across the forecast area early in the work week.

A strong northeast Pacific high coupled with a strong upper level
shortwave trough and surface low will produce strong gradient
winds across the Aleutians through the Alaskan and Kenai
Peninsulas early in the period. The Pacific high pressure will
start to retreat eastward allowing for an upper level long wave
trough to migrate over much of the state on Monday through the end
of the period as a moderately strong ridge of high pressure moves
into the western Bering sea.

The southerly winds and and heavy precipitation, across the
mainland and AKPEN, will start to abate on Sunday evening as an
arctic airmass moves over much of the state. This air mass will
linger through the end of the forecast period bringing northerly
winds and much colder, below normal temperatures across the state.

-DD

&&

.AVIATION...

PANC... MVFR ceilings with a possible rain/snow mix quickly
changing to all rain in the morning. Afternoon conditions vary
between IFR and MVFR ceilings with rain showers then clearing to
VFR overnight to Friday morning.

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1149 AM AKST Thu Jan 23 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1148 AM     Non-Tstm Wnd Gst Unalaska                53.90N 166.54W
01/23/2025  M77 MPH          Aleutians West     AK   Mesonet

&&

Preliminary Local Storm Report
National Weather Service Anchorage AK
1246 PM AKST Thu Jan 23 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0746 AM     Snow             6 SE Valdez             61.11N 146.22W
01/23/2025  M0.9 Inch        Chugach            AK   Emergency Mngr

            SWE .29, 32.4F Calm wind.

&&