Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 612 PM EDT Tue Mar 23 2021 Valid 12Z Sat Mar 27 2021 - 12Z Wed Mar 31 2021 ...Powerhouse weekend Bering Sea low to slam into the Alaskan mainland into early next week... ...Guidance/Uncertainty Assessment... Model and ensemble solutions are better clustered today days 4-8, bolstering forecast confidence in a stormy pattern. There are still system differences to mitigate at mid-smaller scales with usage of a composite solution of the 12 UTC GFS/ECMWF/UKMET/Canadian and the 19 UTC National Blend of Models (NBM) along with some manual adjustments days 4-6 (Saturday-Monday). The 12 UTC GFS/ECMWF/Canadian, the 12 UTC GEFS/ECMWF ensemble means and the 19 UTC NBM were used for days 7/8 (next Tuesday/Wednesday) in a period with gradually growing forecast spread. This methodology also maintains good WPC continuity. ...Weather/Hazards Highlights... A moderating Bering Sea lead system with still favorable upper support will work over the interior into the weekend and support periods of locally enhanced snows and unsettled conditions. Ample downstream energy transference will increasingly focus weekend storminess over the northern then northeastern Gulf of Alaska to support a threat for terrain focusing heavy precipitation into Southeast Alaska before exiting the region. Upstream, a powerhouse low is expected to emerge back into the Bering Sea over the weekend and provide a significant maritime and Aleutians threat. The storm is expected to reach/spread highly unsettled conditions in earnest over the mainland then Gulf of Alaska later weekend through early-mid next week. This would include a substantial threat for enhanced wrapping precipitation and high winds/waves. This has a strong guidance signal to be a major storm. Schichtel Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Fri-Sat, Mar 26-Mar 27. - High winds across portions of mainland Alaska and the Aleutians, Sun-Mon, Mar 28-Mar 29. 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 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