Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
634 PM EST Fri Dec 03 2021
Valid 12Z Tue Dec 07 2021 - 12Z Sat Dec 11 2021
...Stormy pattern continues next week for Alaska...
...Overview and Guidance Evaluation/Preferences and Weather/Hazard
Highlights...
The Alaskan weather pattern will remain active into early next
week as amplified upper troughing brings snowy storm energies
into/across mainland Alaska. This system will weaken as it tracks
through the Mainland, but enhanced winds and lingering snows may
offer a significant local effect.
Ample triple point development down along the southern Alaskan
Gulf Coast by Tuesday should also send a lead front through the
Panhandle region into midweek. Increasingly wet weather will work
into parts of the Southern Coast and southeast Alaska into Tuesday
and Wednesday with a threat for locally heavy snows with the low
genesis, especially across favorable terrain.
Upstream upper trough energies tracking to the Bering Sea by later
next week now seem likely to support a deep low pressure system,
albeit with continuing uncertainty on subsequent track into
Alaska. This system has potential to be quite deep and presents a
significant maritime and onshore threat.
Guidance shows good agreement through Day 4/5 (Tuesday/Wednesday)
and a composite of the well clustered 12 UTC GFS/ECMWF seems to
offer a reasonable solution with above normal detail and
predictability. Forecast spread and uncertainty increases quickly
days 6-8 (Wednesday-next Friday), especially with model run to
run continuity on the next main low towards the Bering Sea. Given
trends and uncertainty, the WPC forecast progs used a blend of the
now quite compatible 12 UTC GEFS/ECMWF ensemble means that offer a
deep low on a middle of the road track between the more varied
models across the Bering into Alaska. This approach also maintains
better continuity with yesterday's WPC forecasts.
Schichtel
Hazards:
- Heavy precipitation across portions of mainland Alaska, Mon, Dec
6.
- Heavy precipitation across portions of the Alaska Panhandle,
Tue, Dec 7.
- High winds across portions of mainland Alaska, Mon, Dec 6.
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