Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
709 PM EDT Sat Oct 16 2021
Valid 12Z Wed Oct 20 2021 - 12Z Sun Oct 24 2021
...Stormy Pattern Continues from the Aleutians through Southern
and Southeast Alaska...
... Guidance and Predictability Assessment...
A rather stormy pattern over parts of Alaska will continue through
at least the next week as a parade of low pressure systems moves
from the Bering Sea/Aleutians into the Gulf. This should help to
maintain mean low pressure across the Gulf through the entire
extended range period. The models show good agreement on this
overall pattern through the first half of the period, so a general
model compromise provides a good starting point. After this, some
bigger differences begin to arise regarding details of both a low
in the Gulf and another low moving across the Aleutians, and how
the two may interact. There's also plenty of uncertainty regarding
exact track and location of low pressure systems as they move
through the region. To help mitigate some of these differences,
the WPC forecast trends quickly towards the more agreeable
ensemble means. This approach allowed for good continuity from
yesterdays forecast, as well as with downstream across the CONUS.
...Pattern Overview and Weather/Hazard Highlights...
The period starts Wednesday with one system weakening in the Gulf
of Alaska as another one deepens to its south and lifts towards
the southern Panhandle by the end of next week. This should keep
unsettled wet weather in the forecast from the southern coast to
the Panhandle. Most places should see just scattered light to
moderate precipitation, though locally heavy precipitation is
likely in some spots, with snow in the higher elevations. The next
system moves across the Aleutians on Thursday-Friday with
widespread precipitation and gusty winds likely to accompany. As
the low moves into the Gulf next weekend, precipitation intensity
and coverage may increase again across the southern
coast/southeast AK/Panhandle region as southerly flow gets pulled
north ahead of the cold front.
Temperatures from the Aleutians to the Panhandle should remain
near or below normal through the period as surface low pressure
and upper level troughing becomes established over the region.
Into interior and northern Alaska, a warming trend is expected by
the early to middle part of next week as upper level ridging tries
to work over the state. Daytime highs, especially across the
northern half of the state could be 10 to 20 degrees above normal
through the second half of next week and next weekend.
Santorelli
Additional 3-7 Day Hazard Information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range Alaskan products including 500mb, surface
fronts/pressures progs and sensible weather grids can also be
found at:
https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml
https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html