Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
646 PM EDT Wed Mar 16 2022
Valid 12Z Sun Mar 20 2022 - 12Z Thu Mar 24 2022
...Pattern Overview...
One main feature near Alaska for the medium range period will be a
mean upper low with possibly multiple centers of focus at times
meandering in the Gulf of Alaska. Energies near the Alaska
Peninsula combined with an active storm track across the
northeastern Pacific will serve to redevelop and reinforce mean
low pressure across the Gulf next week. A series of low pressure
systems will bring a sustained period of unsettled weather through
the Panhandle and occasionally up into the southern coast for much
of the period. A low near the Kamchatka Peninsula will swing a
cold front through the Aleutians and lead low focus over the
Bering Sea toward southwest AK and possibly even the Gulf of
Alaska next week, but a blocky upper ridge setting up near/over
Mainland Alaska may limit progression. Downstream in this pattern,
upper troughing would also begin to amplify more over an unsettled
Mainland as an upper ridge/high settles into northwest AK, albeit
with less certainty.
...Guidance/Predictability Assessment...
A composite of overall compatible guidance from the 12 UTC
GFS/ECMWF/UKMET/Canadian models produces a reasonable solution for
Day 4/Sunday, but embedded system variance becomes an issue by
days 5-8 especially over the Bering Sea, Gulf of Alaska and the
Mainland. The latest GEFS/NAEFS/ECENS means remain decently
clustered though in this period, albeit with much less system
definition. Accordingly, kept the best clustered ECMWF along with
the GEFS/ECMWF/NAEFS means for days 5/6 (Monday/Tuesday) to add a
bit more detail consistent with lowering predictability before
going full ensembles days 7/8 (next Wednesday/Thursday).
...Weather/Hazard Highlights...
Precipitation through much of the period is expected to focus from
south-central Alaska to especially southeastern Alaska given the
general northern Pacific storm track. The region will experience
varying rainfall intensities depending on uncertain surface low
progressions. While precipitation does not appear to be very
intense overall, recent heavy rain/snow across the area could make
it more sensitive to additional impacts. Amounts seem most likely
to pick up early next week with expected organized system
approach. Farther north, some periods of snow are also possible
for the eastern mainland over the weekend and unsettled conditions
may persist over the Interior next week if sufficient troughing
develops aloft. Meanwhile, slow low/frontal system progression
over the Aleutians and the Bering Sea next week may lead to
subsequent low re-development and weather focus through southwest
AK to the Gulf of Alaska next midweek. There is also some signal,
especially from an outlier GFS solution, to support deeper low
development over the Bering Sea in this pattern.
Schichtel
Hazards:
No significant hazards are expected over Alaska during this
forecast period.
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