Mill Bay, Alaska 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

541
FXAK68 PAFC 171240
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
440 AM AKDT Thu Apr 17 2025

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

A highly amplified pattern, one more akin to fall than spring,
will shift east over the weekend, bringing a steady end to
precipitation and wind to most of the region by Saturday. However,
one more day of breezy conditions and widespread light rain is
expected today as the main upper level trough and a few attendant
shortwaves move over the area. The flow aloft will be largely out
of the south, focusing more the moderate precipitation on the
eastern Sound (Valdez/Cordova) and to a lesser degree Seward.
Inland areas will see rain spread southwest to northeast through
the day and into the evening as a few shortwaves move overhead.
Snow levels will slowly fall below 1000 feet by tomorrow morning
as cooler air moves in from the west.

For Friday, most of the upper level forcing for precipitation
will have moved into the Gulf, leaving behind a weak low in the
northern Gulf and a more unstable airmass. The low in the Gulf may
keep some areas around the Sound, particularly near Valdez and
Cordova, a little on the wet side while the instability inland
yields shower development near south and west facing mountains.
These showers should follow a diurnal cycle, with snow falling
above approximately 800 ft in elevation. It may make it down lower
in a few areas, but little to no accumulation is expected during
the afternoon hours at or near sea level.

Saturday appears to be the nicest day of the week, with shortwave
ridging bringing in some sunshine for many areas. A weak shortwave
trough embedded in the flow is expected to move over the Alaska
Range, which may lead to some showers or cloudier conditions over
the Susitna and Copper Valleys, but from the southern Mat-Su
south through the Inlet and into the PWS should be sunny or at
least mostly Sunny. This looks to extend into the first half of
Sunday, but clouds and precipitation will slowly push back in to
Kodiak by Sunday morning and then into Southcentral late Sunday
into Monday morning.

-CJ

&&


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

Currently, there is a low sitting in Bristol Bay slowly weakening
as it tracks eastward. This low is allowing for widespread
precipitation in the Southwest mainland including the Alaska
Peninsula. Precipitation is in the form of rain or snow depending
on the region. Closer to the western coast, there is band of cold
air dipping all the way down from the Kuskokwim Delta coast
including Nunivak Island to the Alaska Peninsula region. Snow is
the dominant precipitation type in these areas. Further inland,
flow is more southerly, so warmer temperatures are present and
thus, rain or rain/snow are the dominant precipitation types.
Another impact is gusty winds particularly in gap regions of the
Alaska Peninsula. The cold air from northerly winds is reinforcing
these gusty winds. Ridging is present in the central Aleutians
west of Unalaska, allowing for calm winds and low level stratus.
Finally, a front is passing through the western Aleutians,
bringing small craft winds and precipitation. These conditions
will remain through Friday afternoon.

Friday night into Saturday, the low weakens and moves further
east, allowing wind speeds and precipitation chances to dwindle as
the ridge pushes in. Also, winds will turn southerly, allowing
for warmer temperatures across Southwest Alaska. On the heels of
the ridge, however, is not one but two medium sized upper lows
swinging in from the west, with the second low being the larger of
the two. The first low drives a front into the central/eastern
Aleutians by Saturday afternoon, bringing increased winds speeds
and precipitation mostly in the form of rain. The front pushes
into the Southwest mainland by Sunday morning, driving
precipitation chances up, but not so much in the way of wind
speeds apart from coastal regions. Precipitation will be mostly in
the form of rain apart from the western part the Kuskokwim Delta
including Nunivak Island, which will receive snow or snow/rain
depending on how low the temperatures are. By Sunday afternoon, it
will the second low`s turn to play. The second low is larger than
the first and will bring increased wind speeds and precipitation
chances to most of the Aleutians and the Alaska Peninsula regions
by Sunday afternoon into the evening hours.

-JAR

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

The majority of active weather will be working its way across the
Aleutians and Bering through Tuesday before crossing over into
the Gulf of Alaska for Wednesday. A broad surface ridge slides
across the Interior into Canada by Monday, leaving an extended
area of low pressure from the Russian Far East to the Canadian
Border by Wednesday. Uncertainty with the weather features
increases through the period, especially considering an energetic
GFS accelerating ahead if the other models through midweek. A well
developed surface low in the Western Bering on Sunday extends a
front across the Central Alaska Peninsula and Eastern Aleutians
Sunday. Ahead of the front snow changes to rain across the
Northern Bering through St Matthew and Nunivak Islands. All rain
is expected over Bristol Bay and areas South for Sunday. Rain
pushes over Kodiak Island and Southwest Alaska with areas of
possible freezing rain over the Northern Bering for Monday. The
Western Bering low progresses into the Eastern Bering by Tuesday,
before crossing the AKPEN for Wednesday. Areas of moderate rain
continue across Southcentral Alaska through late Tuesday before
diminishing. A strong North Pacific low and front spreads locally
heavy rain across the Western Aleutians and Bering late Monday,
and continues into the Central Aleutians and Bering for late
Tuesday into Wednesday.

- Kutz

&&

.AVIATION...

Widespread south to southeast winds are expected at all levels
over the terminal today. A shortwave may push some light rain
over the Terminal this morning. Turnagain winds should keep cigs
and vis mostly VFR, but MVFR is possible between 15 and 18Z with
the rain. After the rain lift through, VFR conditions are expected,
though some showers may develop over the mountains. More rain and
lower cigs will move in Fri morning.


&&


$$