Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 459 PM EST Mon Dec 06 2021 Valid 12Z Fri Dec 10 2021 - 12Z Tue Dec 14 2021 ...Another Major Storm for Alaska... ...Overview and Guidance Evaluation/Preferences and Weather/Hazard Highlights... Strong upper energies supporting a deep Bering Sea storm Thursday are slated to transfer robustly downstream over Southwest Alaska and the Alaskan Peninsula/Kodiak Island to re-develop a powerhouse low near the Kenai Peninsula by Friday whose large circulation will affect much of the state. Subsequent system track over the eastern Gulf of Alaska next weekend into early next week will act to spread the threat of high winds and Gulf waves along with heavy coastal rains and terrain enhanced heavy snows from south-central Alaska to the southeast Panhandle. Expect much below normal temperatures will settle over the Aleutians through southwest and southern portions of the state in the wake of system passage. All these threats are detailed in the latest WPC Day 3-7 Hazards Outlook product listed and linked below. 12 UTC GFS/ECMWF/UKMET/Canadian solutions seem well clustered through days 4/5 (Fri/Sat), bolstering forecast confidence. The GFS/ECMWF remain best clustered and in line with ensembles and WPC continuity Days 6/Sun before forecast spread become more daunting day 7/8. Prefer by then a composite of still reasonably compatible GEFS/ECMWF ensemble means in a pattern with rapidly decreasing predictability. There is a slowly growing guidance signal to support additional Bering Sea storm genesis into these longer time frames, but with an uncertain downstream track and re-development toward Alaska. The 12 UTC GFS seems a distinct outlier more directed to mainland Alaska compared to a better supported track suppression to the Gulf of Alaska, albeit with varied 12 UTC ECMWF/Canadian and ensemble member details. Schichtel Hazards: - Heavy precipitation across portions of mainland Alaska, Thu, Dec 9. - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Fri, Dec 10. - High winds across portions of mainland Alaska and the Aleutians, Thu-Sat, Dec 9-Dec 11. - Much below normal temperatures for parts of mainland Alaska and the Aleutians, Sat-Mon, Dec 11-Dec 13. 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