Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
758 PM EDT Tue Nov 2 2021
Valid 12Z Sat Nov 6 2021 - 12Z Wed Nov 10 2021
...Overview and Model Guidance...
Offshore storms will mainly affect coastal Alaska during this
forecast period. The flow will feature some potent Gulf of Alaska
lows rotating around a closed upper trough and as escaping Bering
Sea and Gulf of Alaskan impulses lift around the western periphery
of an amplified but slowly weakening western Canada to Alaskan
Interior upper ridge.
In terms of the model guidance, the 12Z UKMET appeared closest to
the ensemble means with respect to the closed upper low over the
Gulf of Alaska through the weekend, so this model was weighted a
bit more through Day 5. The CMC strayed from the consensus by
having the low well to the north and closer to the coast, and the
GFS a bit to the south of the ensemble means.
...Weather/Hazard Highlights...
A compact and moist extratropical low associated with former
Typhoon Malou is expected to lift from the eastern to northern
Gulf of Alaska Friday/Saturday and offer some focus for enhanced
precipitation into Southeast to south-central coastal Alaska.
Meanwhile, Bering Sea systems will combine with energies lifting
on the western periphery of an amplified Interior upper ridge
position to focus periods of enhanced precipitation into western
Alaska. In this pattern, the central and eastern Interior through
the North Slope should enjoy much above normal readings through
the weekend with some readings more than 20 degrees above normal
before moderating into next week. Meanwhile, deep energy digging
underneath into the Gulf of Alaska late week into early next week
will present a favorable environment for offshore storm genesis
with amplified/closed upper trough development to present a
periodic maritime and southern/southeastern coastal tier threat.
However, particular deep storm depiction at these longer time
frames remains uncertain given run to run guidance variance and
limited ensemble clustering.
Hamrick/Schichtel
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