Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
420 PM EST Sun Feb 21 2021
Valid 12Z Thu Feb 25 2021 - 12Z Mon Mar 01 2021
...Stormy Pattern from the Bering Sea to the Mainland/Gulf of
Alaska...
...Overview and Guidance/Uncertainty Assessment...
The 12 UTC GFS/GEFS mean and 12 UTC ECMWF/ECMWF ensemble mean
mid-larger scale solution evolutions are reasonably well clustered
through medium range time scales. A composite solution is
preferred to highlight the most predictable weather features as
numerous smaller scale system differences linger. The WPC medium
range product suite was derived from this blend along with the
National Blend of Models in a pattern with near average forecast
predictability/uncertainty. This solution maintains good WPC
product continuity in a pattern with overall above normal
predictability.
...Weather/Hazards Highlights...
A series of deepening lows in an energetic Pacific stream will
work across the Bering Sea/Aleutians all week in an active
pattern. This favors a downstream warming trend across southwest
Alaska and much of the Interior this week, but lingering upper
troughing and flow underneath may inhibit warming over the North
Slope and possibly the eastern Interior. A main storm track will
focus precipitation and wind/waves into the Aleutians, the AKpen
and southwest Alaska as they progress eastward, with energies to
track into an unsettled Gulf of Alaska to support periodic heavier
precipitation into southern and southeast Alaska with lows
Thursday and again over the weekend. Farther north, this pattern
will also allow ejecting Bering Sea system energies to work inland
across the Interior along with support for moderate swaths of snow
to focus near a southern Interior wavy front with greatest
potential by Thursday and over the weekend. There is also an
emerging guidance signal that shows a threat of a deep low
development and approach into the Aleutians in about a week to
monitor.
Schichtel
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards 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