Alaska Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
541 PM EST Tue Jan 21 2020
Valid 12Z Sat Jan 25 2020 - 12Z Wed Jan 29 2020
...Well below average temperatures for most of mainland Alaska...
Guidance still offers good consensus in showing that an upper
level ridge will build northward over the Bering Sea from Fri
onward, with a closed upper high migrating toward eastern Russia
by early next week. Forecast confidence is high that the
downstream implication for much of mainland Alaska will be that a
strong surface high will intensify near the Bering Strait as
increasingly cold conditions settle over most of the state. High
and low temperatures approaching or even exceeding 20 deg F below
average are possible by late week into the weekend, especially
across the Interior, southwestern mainland Alaska, and northern
Alaska Peninsula. Arctic shortwave energy will dive south along
the eastern periphery of the upper ridge, the amplitude of which
now looks increasingly sufficient to interact with additional
shortwave energy from an active North Pacific jet. This would
result in potential development of a closed upper low somewhere
near southern mainland Alaska or northern Gulf of Alaska late
week. This setup should keep Southeast Alaska with relatively high
precipitation chances due to the active storm track. The threat
for snow may also work north into southern mainland Alaska this
weekend and linger well into next week with upper low development
and potential reinforcement. The models though still continue to
struggle with the evolution and progression of a series of low
pressure systems crossing the North Pacific and the Gulf of Alaska
during the extended period and interactions with the potent
northern stream energies. Accordingly, the specifics of this
aspect of the forecast remains more chaotic with below average
predictability and continuity.
Overall, the WPC medium range product suite was mainly derived
from a blend of the 12 UTC ECWMF along with the most compatable 12
UTC GEFS/NAEFS/ECMWF ensemble means days 4-8.
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
Hazards:
- Much below normal temperatures for most of mainland Alaska,
Fri-Tue, Jan 24-Jan 28.
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