Area Forecast Discussion
Issued by NWS Anchorage, AK

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13

FXAK68 PAFC 221337

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
537 AM AKDT Fri Sep 22 2023


A deep vertically stacked low continues to drift slowly eastward
and away from Kamchatka, while hugging the coast of Northeast
Russia. An occluded front extends southeastward from the low and
has essentially stalled over the Alaska Peninsula due to the
remnants of a high amplitude ridge over the western half of the
state. Despite overcast skies and lingering showers along the
front, most of Southwest is currently dry with clear skies mixed
with areas of patchy fog and low stratus this morning, largely
thanks to the aforementioned ridge of high pressure. Things are
more active over the western and southern Bering where a 120+ knot
upper level jetstream spans from south of Kamchatka to across the
Aleutians and back into the North Pacific before reaching the
Alaska Peninsula. Numerous smaller disturbances are forecast to
track within this stronger flow, skirting immediately south of the
Central Aleutians through the weekend. Meanwhile, a trough
remains over the Gulf of Alaska with all of the precipitation and
upper-level energy being directed into Southeast Alaska.
Southcentral thus remains under weak high pressure, which is
likely to persist through early next week, bringing a welcomed
multi- day stretch of dry and sunnier conditions to the region.



Model guidance is in reasonable agreement this morning,
especially with the synoptic features. A broad upper low over the
western Bering will send multiple shortwaves across the Southern
Bering and into the North Pacific over the next couple of days.
There continues to be minor differences in the speed and evolution
of each wave, first late Friday into early Saturday over the
Alaska Peninsula, and then again late Sunday over the Western



PANC...VFR conditions and light winds are expected to prevail
today. There is potential for some patchy fog to develop near the
airport this morning, but any fog should quickly dissipate with
the onset of daytime heating.



Pretty quiet across Southcentral Alaska this morning with the only
notable feature being a weak low spinning over the northern Gulf
producing some scattered showers near the vicinity of the low. High
pressure will continue to build in from the west as an amplified
upper level ridge gradually expands over the next several days.
This will result in quiet and drier weather over the weekend and
likely continuing into early next week. However, it will
definitely start to feel like fall with the next few days starting
out with crisp morning temperatures, especially for areas that
see clouds clearing out during the overnight hours. The Copper
River Basin is expected to see the coldest morning temperatures
this weekend with lows bottoming out in the 20s. Near normal
temperatures can be expected during the day with partly to mostly
sunny skies for much of the region.


through Sunday)...

Forecast remains on track. The current active pattern over the
eastern Bering and Aleutians this morning will trend towards a
more settled pattern through the weekend and into early next week
as the longwave pattern becomes more zonal and shifts south of the

A low in the northwestern Bering Sea extends its front across the
eastern Bering and Aleutians early this morning. Winds along and
behind the front will weaken today as the front sweeps well
eastward of its parent low pressure system. The front will
continue weakening as it lifts across the AKPen today and then
into Southwest Alaska this evening, bringing a quick shift of westerly
winds. Expect scattered showers for the eastern Aleutians and
Bering, AKPen, and coastal Southwest Alaska through the weekend as
the system gradually dissipates.

Further to the west, a weak low will pass just to the south of
the Aleutian Islands today, however most of the precipitation and
winds should remain over the North Pacific. Widespread zonal flow
is expected across the Bering and Aleutians through the weekend,
with winds likely only reaching small craft at most on Saturday.
By Sunday morning, an upper low and attendant surface low track
into the western Bering from the Kamchatka Peninsula.
Precipitation spreads eastward throughout the day and reaches the
eastern Aleutians by Sunday night. Sustained winds are advertised
to remain mostly below small craft.


.LONG TERM FORECAST (Days 4 through 7: Monday through Thursday)...

Key features in the long term include a deep longwave trough over
the northern Bering extending southward to the Gulf of Alaska. An
upper level ridge builds to the east over the Alaska-Yukon border.
Model agreement beyond the midweek timeframe diverges greatly, and
the GFS solution appears to be the outlier. There is higher
confidence at this point in time in the EC/Canadian solution,
which depicts a secondary upper level trough entering the Bering
from Siberia early Wednesday.

For the most part, resultant weather across Southcentral appears
to be generally quiet for the middle of next week. The EC
advertises a Gulf low over the Panhandle lifting northward late
Wednesday. Upper level waves associated with this low may produce
precipitation over the Copper River Basin through the end of next week.
Farther west, would expect unsettled weather over the Bering as a
low traverses from west to east and arrives over Southwest Alaska
by Thursday. There is growing consensus among model solutions that
a deeper trough will arrive over the central Aleutians by the end
of the week, though there is little confidence on the timing and
track of this feature.



LONG TERM...KO is the U.S. government's official web portal to all federal, state and local government web resources and services.