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