Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 610 PM EST Mon Nov 28 2022 Valid 12Z Fri Dec 02 2022 - 12Z Tue Dec 06 2022 ...Heavy snow/ice and freezing rain threats from Southwest/Western Alaska into the Interior/North Slope to repeat over the next week... ...Guidance/Predictability Assessment and Preferences... The 12 UTC GFS/ECMWF model solutions, and to some extent the Canadian, seem best clustered through Friday and the weekend in a pattern with above average predictability in line with GEFS/ECMWF ensembles and continuity. Embedded system differences grow next week, but guidance offers a similar larger scale flow pattern aloft, bolstering forecast condidence through these longer time frames. Accordingly, prefer a blend mainly of the GFS/ECMWF and GEFS/ECMWF ensemble means with blend weightings set strongly toward the models Friday-Sunday, then with most emphasis on the ensemble means by early next week. This maintains excellent WPC product continuity. ...Weather/Hazards Highlights... Models and ensembles agree to sustain an amplified mean upper ridge position up over western Alaska. The ridge will support unseasonably warm conditions over much of the mainland outside of the southeastern Interior and the Southeast Panhandle, with greatest warm anomalies expected from western Alaska through the North Slope over the next week. This solution is well supported in models and ensembles, bolstering forecast confidence. While there remains uncertainty with the interactions of Bering Sea to Chukchi Sea systems moving around or more bodily into the downstream ridge over the mainland during this forecast period, the aforementioned preferred guidance composite highlights short range mid-late week threats for high winds and heavy snow/ice and/or freezing rain across Southwest/Western Alaska into the Interior/North Slope, and in particular later Friday through Saturday as approaching system energies channel/focus deeper moisture into the region. The supporting upper shortwave now has a more robust signal in guidance, bolstering forecast confidence in the threat whose surface pattern may also include some potential for enhanced winds and coastal waves/flooding. The overall upper pattern seems to favor the potential for repeat episodes of these threats later period as well as Bering Sea upper trough energies work into/around the amplified/rebuild upper ridge over the mainland, but the details/timings of embedded systems are less certain by early next week. Downstream of the upper ridge, cold high pressure will linger over southeastern Interior Alaska valleys and linger across the Panhandle through later this week with temperatures around 20+ degrees below average over the Panhandle. Additional system energies digging to the lee of the mean upper ridge position should act to maintain unsettled and moderated/cooled flow over the region through much of the rest of the period that could include some periodic enhanced winds with eastern Gulf of Alaska system digging/passage. Schichtel Hazards: - Heavy precipitation across portions of mainland Alaska, Fri-Sat, Dec 2-Dec 3. - High winds across portions of mainland Alaska, Fri-Sat, Dec 2-Dec 3. - High winds across portions of the Aleutians, Sat-Sun, Dec 3-Dec 4. - High winds across portions of mainland Alaska, Sun, Dec 4. - Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, Thu-Fri, Dec 1-Dec 2. 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