Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
704 PM EDT Fri Oct 29 2021
Valid 12Z Tue Nov 02 2021 - 12Z Sat Nov 06 2021
...A stormy pattern for Alaska continues next week...
...Overview and Model Guidance...
A stormy weather pattern with potent offshore storms will continue
to affect portions of Alaska next week. 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. Guidance continuity and
variance with embedded features is not stellar throughout medium
range time scales, but a blend of best clustered guidance from the
12 UTC GFS/ECMWF with the GEFS/ECMWF ensemble means (that do have
compatible larger scale pattern evolutions) and the 19 UTC
National Blend of Models (except QPF/PoPs) does offer a seemingly
reasonable solution that maintains decent WPC product continuity
when weighting shifts increasingly from the higher resolution
models that offer more detail consistent with higher
predictability for days 4/5 (Tuesday/Wednesday) and then quickly
shifting main focus to the ensemble means as predictability
quickly decreases into days 6-8 (Thursday-next Saturday).
...Weather/Hazard Highlights...
A lead storm system is expected to wrap into the northwest Gulf of
Alaska Tuesday and then weaken around the periphery of the
Interior upper ridge. There is some threat for high waves/winds,
with heavy precipitation spreading into southern Alaska. Some
activity will then shear northward to bring a more modest weather
focus into western Alaska. On the heels of this system, a moist
extratropical low associated with current western Pacific Tropical
Storm Malou should meanwhile lift into the eastern then northern
Gulf of Alaska Tuesday past midweek. This offers another threat
for high winds/waves as heavy precipitation works inland from
southeast through southern Alaska and possibly into the AKpen and
Kodiak Island. Additional storm systems will also through this
period 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 later next week into next weekend is less predictable
for individual systems, but seemingly still potent, presenting a
continued favorable environment for new and ample storm genesis
under and around an amplified/closed upper trough position.
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, Mon-Tue,
Nov 1-Nov 2.
- Heavy precipitation across portions of mainland Alaska, Wed-Thu,
Nov 3-Nov 4.
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