NWS Anchorage, AK wrote its last area forecast discussion before the first event at Apr 14, 4:33 PM AKST, 10 hours 27 minutes earlier.
Area forecast discussion, Apr 14, 4:33 PM AKST, 10 hours 27 minutes before
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
533 PM AKDT Mon Apr 14 2025
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: This
afternoon through Thursday afternoon)...
Aside from some isolated showers and breezy winds, expect fairly
quiet weather for Southcentral through tomorrow morning. By
tomorrow afternoon, the weather becomes much more active as a
North Pacific low pushes its front into Southcentral. Strong winds
are likely, with gusts of 75 mph or greater possible. In
addition, expect a prolonged duration of low-elevation rain and
high-elevation snow along the north Gulf coast. The following
watches are in effect, with the potential for additional products
to be issued as we continue to assess the forecast:
- High Wind Watch for Anchorage Hillside and Eagle River: From
late Tuesday night through Wednesday night. Southeast winds
gusting as high as 90 mph.
- High Wind Watch for Portage: From Wednesday morning through late
Wednesday night. East winds gusting as high as 90 mph.
Diving into the details: For the rest of today, expect offshore
flow and quieter weather as a compact low currently near Cape
Suckling continues to slide eastward towards Southeast Alaska.
Clearer skies have allowed surface temperatures to climb into the
30s and 40s across Southcentral. Instability from warm near-
surface temperatures is even producing showers along the slopes
surrounding Mat Valley, marking our gradual transition into our
convective warm season.
Through tomorrow, cloud cover will slowly increase as the front
of a North Pacific low pushes into Southcentral. The front will
first reach Kodiak Island tomorrow morning, then reach the north
Gulf coast by tomorrow evening. Southeast flow will lead to
upslope enhancement along Eastern Kenai; this, along with a
prolonged duration of moderate to heavy precipitation, could lead
to rain totals of 2 inches or greater in some areas. On the lee of
the Kenai and Chugach Mountains, downsloping will keep parts of
Anchorage, Western Kenai, Mat Valley, and Copper River Valley
fairly dry. Warm air advection with this front will likely lead to
rain for all but Thompson Pass and Turnagain Pass, with snow at
higher elevations.
The biggest story with this storm, however, will likely be the
winds. A tight surface pressure gradient will lead to strong
winds, especially through east- or southeast-oriented gaps and
passes, from late Tuesday night through most of Wednesday.
Currently, the areas of highest concern are the Anchorage
Hillside/Eagle River and Portage Valley, where models are showing
a strong and consistent signal for winds gusting to 75 mph or
greater. For the Anchorage Hillside/Eagle River zone, however,
there is a question of whether a strong north-south pressure
gradient will keep the strongest winds mostly over the Chugach
Mountains/Turnagain Arm and out of the Hillside. Other areas not
under a High Wind Watch will likely also experience strong winds,
albeit under 75 mph. These areas include Knik River Valley (Palmer
area), Turnagain Arm, and gaps and passes in the Kenai Mountains.
-Chen
&&
.SHORT TERM FORECAST SOUTHWEST ALASKA/BERING SEA/ALEUTIANS
(Days 1 through 3: Tonight through Thursday evening)...
Key Points...
* A Winter Storm Warning is in effect for the Eastern Aleutians
from 4 AM Tuesday through 1 AM Thursday. Expect snow and
blowing snow with 8 to 20 inches of accumulation and gusts of 50
to 65 mph.
* A Winter Weather Advisory is in effect for the southern AK
Peninsula from 4 AM to 11 AM Tuesday. Expect snow and blowing
snow with 2 to 6 inches of accumulation and wind gusts up to 45
mph.
* A Winter Storm Watch is in effect from Tuesday evening through
Wednesday evening for the Kuskokwim Delta Coast. 2 to 6 inches
of snow is possible along with winds gusting as high as 45 mph
and visibility as low as one quarter mile.
A weak shortwave lifting across the eastern Bering today will
give the Kuskokwim Delta a round of light snow showers this
afternoon and evening before it lifts northward into Western
Alaska. Elsewhere, plenty of low stratus covers the Bering and
Aleutian Chain. A second wave over the western Bering is dropping
south toward the central Aleutians.
While conditions are fairly quiet as of Monday afternoon,
attention quickly shifts to a powerful North Pacific low that will
send its front into the Eastern Aleutians and southern AKPEN by
early Tuesday morning and the rest of the AKPEN by late Tuesday
morning. The storm track looks to be dialed in at this point,
with Unalaska likely remaining on the western/cold side of the
storm. Therefore, they will maintain a northerly wind and cold air
with the storm. The southern AKPEN, while they will start out as
snow early Tuesday morning, will see a changeover to rain/snow mix
and eventually all rain Tuesday afternoon and evening. However, a
few inches of snow along with gusty easterly winds are likely
from King Cove west to False Pass before the warmer air arrives
and a changeover of precipitation occurs.
One other key detail, is that 12z and 18z guidance continues to
hint at a stronger system, with a deeper moisture fetch and
stronger winds on both sides of the low. Even with an increase in
the expected intensity of this system, the forecasted impacts look
on track.
Unalaska will likely bear the brunt of this storm due to being
within the best moisture axis and maintaining cold air with the
northerly winds, not to mention that the northerly winds will be
strong and gusty. Snow, blowing snow, and poor visibility are
looking more likely for Unalaska Tuesday morning through Thursday
morning with the heaviest snow falling Tuesday evening through
Wednesday evening. The tricky part of this forecast is that
guidance is showing that temperatures with this event will be
about 2 degrees warmer than that of the system a couple weeks
back. This ever-so-slightly warmer airmass could mean that
temperatures near sea level climb to between 33 and 35 degrees,
allowing for some rain to mix in at times. For higher elevations
around Unalaska, temperatures should remain cold enough for all
snow with blowing snow.
There also remains a little bit of uncertainty with regards to
Akutan and how much snow they might see. Due to being closer to
the storm track, warmer air could work in and change snow over to
rain/snow mix Tuesday evening which will cut into snow
accumulations. Heavy snow is still possible there, especially if
cold air hangs on longer. Nikolski looks to be cold enough for all
snow, but looks to be a little too far west and out of the best
moisture axis for heavy snow. With all that, have issued a Winter
Storm Watch for the Eastern Aleutians from early Tuesday morning
through early Thursday morning for the heavy snow threat, blowing
snow, reduced visibility, and strong northerly winds.
The front then makes it to mainland Southwest Alaska by Tuesday
afternoon. Precipitation looks to initially start out as snow
across Bristol Bay then quickly change to rain/snow mix and rain
Tuesday evening as warmer air works in from Kamishak Gap. Again,
guidance is trending stronger with this front, with more moisture
and stronger winds. There is growing likelihood of accumulating
snow and blowing snow into the Kuskokwim Delta Coast late Tuesday
into Wednesday. Warmer air looks to advance north into the
Kuskokwim Delta and Kuskokwim Valley by Wednesday afternoon and
evening which will change precipitation to rain/snow mix and rain
by then for most locations with the exception of the far
northwestern Kuskokwim Delta coast.
Showery and unsettled conditions continue into Thursday across
the southwestern mainland, AKPEN, and Eastern Aleutians.
Meanwhile, the next front approaches and moves over the western
Bering and Western Aleutians Wednesday night into Thursday
bringing rain to the area. Stay tuned for forecast updates as the
active pattern continues across the Eastern Aleutians and
southwestern mainland.
-TM/DAN
&&
.LONG TERM FORECAST (Days 4 through 7/Fri through Mon)...
Low pressure will push into the central Aleutians by midweek,
then move up into the AKPEN for Thursday and into the northern
Gulf by the end of the week. This low will bring a widespread mix
of rain and snow to southcentral for Friday and Saturday, becoming
more showery as the low moves east into the panhandle by Sunday.
Behind this system, high pressure will build north into the Gulf
on Sunday to help dry things out.
In the west, a Bering low will stall out in the central Bering
and begins to weaken as it remains nearly stationary through
Monday. This system will bring periods of rain and windy
conditions to the the Aleutians and coastal western Alaska, but
there remains some uncertainty as to whether this system will
remain strong or stay in place.
- Baker
&&
.AVIATION...
PANC...A weak Turnagain Arm wind is expected to move over the
Terminal around 6Z tonight. It will strengthen Tuesday afternoon
when a coastal ridge begins to build. Otherwise, expect VFR
conditions.
&&