Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
556 PM EST Tue Feb 14 2023
Valid 12Z Sat Feb 18 2023 - 12Z Wed Feb 22 2023
...Blizzard Threat for Southwest Alaska Friday into Saturday...
...Pattern Overview and Weather/Hazard Highlights...
A closed low/trough will be present over the Bering/North Pacific
and send lead shortwave energy and a deepened surface system
toward the Southwest Mainland/eastern Aleutians; which with
lingering uncertainties to the details may lead to high winds and
a threat for blizzard conditions for portions of
western/southwestern Alaska Friday into Saturday. Energies and
surface system progression downstream across the northern Gulf of
Alaska will meanwhile lead into a moderately wet period for
Southeast Alaska over the weekend.
Upstream, another upper-level trough developing in the northwest
Pacific will then track gradually eastward while deepening into a
closed low into next week to the western Bering Sea. This should
lead to downstream upper ridge building by next week up into/over
the mainland. With potentially deepened low pressure over the
Bering, parts of Alaska with could experience the development of
some enhanced winds and light to moderate precipitation. This
appears likely to spread across the Aleutians, Bering Sea/maritime
interests and eventually into western/southwestern AK heading into
next midweek. Meanwhile, also expect some precipitation to linger
across the southern coast and into the Southeast where activity
may be further enhanced by northern stream energy next week,
digging into the eastern Gulf of Alaska in amplifying flow to the
lee of the aforementioned building mainland upper ridge.
...Model Guidance/Predictability Assessment...
Overall, guidance offers a similar large scale pattern evolution
that amplifies significantly over medium range time scales, but
differ significantly from short range time frames with embedded
smaller scale system intensities and tracks. Prefer a mainly GEFS
ensemble mean and ECMWF ensemble mean composite days 4-8 with
manual adjustments applied at WPC to ensure sufficient depth
consistent with system predictability. This maintains max product
continuity.
Schichtel
Hazards:
- High winds across portions of Southwest Alaska, Fri, Feb 17.
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