Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
726 PM EDT Thu Oct 28 2021
Valid 12Z Mon Nov 01 2021 - 12Z Fri Nov 05 2021
...Overview and Model Guidance...
A complex weather pattern will remain quite stormy around much of
Alaska through medium range time scales. The flow will feature
several potent Bering Sea, Arctic, and Gulf of Alaskan surface
lows rotating within energetic/closed mean upper troughs over
these areas and around the periphery of an amplified western
Canada to Interior mean upper ridge. The storms will include a
moist and deepened extratropical low associated with current west
Pacific Typhoon Malou. 12 UTC GFS/ECMWF solutions seem well enough
clustered days 4-6 (Monday-Wednesday) with the main storms and a
compromise between the two for system amplitude differences across
the higher latitudes and elsewhere also seems reasonable
considering near average but slowly decreasing
predictability.ÂForecast spread and uncertainty increases more
rapidly into day 7/8 (Thu-next Friday) when a solution more
weighted to the still compatible but less detailed 12 UTC
GEFS/ECMWF ensemble means seem a better way to go given well
organized systems remain depicted and manual adjustments can be
applied to ensure sufficiently deep lows consistent with favorable
upper support.
...Weather/Hazard Highlights...
A storm over the east-central Gulf of Alaska Monday is expected to
wrap into the northwest Gulf Tuesday and weaken while lifting
northward over western Alaska and into the Arctic Ocean around the
Interior upper ridge. A threat for high waves/winds and heavy
precipitation will spread across southern Alaska before lifting
into higher latitudes with a more modest weather focus. On the
heels of this system, guidance indicates that a moist and deepened
extratropical low associated with current western Pacific Typhoon
Malou will lift into the eastern Gulf of Alaska Tuesday and rotate
to the northern Gulf by Wednesday. This offers another threat for
high winds/waves and heavy precipitation spread inland from
southeast to southern Alaska and onward. Additional storm systems
will meanwhile work over the Bering Sea as a maritime threat and
also spread enhanced winds/precipitation across the region and
into western Alaska mainly early-mid week. Energy refresh into the
Gulf of Alaska mid-later next week is less predictable for
individual systems but seemingly still potent, presenting a
continued favorable environment for additional storm genesis.
In terms of temperatures, most locations across central and
eastern portions of the mainland should enjoy above normal
readings next week under the amplified and stabilizing upper
ridge, with some areas up to 20 degrees above normal. However,
readings should be closer to normal or perhaps slightly below for
the western portion of the mainland, the Aleutians and the
Southeast Panhandle.
Schichtel
Hazards:
- Heavy precipitation across portions of mainland Alaska, Sun-Tue,
Oct 31-Nov 2.
- High winds across portions of mainland Alaska, Sun, Oct 31.
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