Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 709 PM EDT Mon Mar 22 2021 Valid 12Z Fri Mar 26 2021 - 12Z Tue Mar 30 2021 ...Stormy pattern for Alaska... ...Guidance/Uncertainty Assessment... The 12 UTC ECMWF/UKMET seem better clustered with 12 UTC GEFS/ECMWF ensemble means and WPC continuity from yesterday than the newly upgraded 12 UTC GFS and the 12 UTC Canadian. The WPC Alaskan medium range product suite was primarily derived from a composite blend featuring the 12 UTC ECMWF/UKMET days 4-5 (Friday-Saturday) before opting for the 12 UTC ECMWF and increasingly the 12 UTC GEFS/ECMWF ensemble means days 6-8 (Sunday-next Tuesday) amid growing forecast spread and decreasing forecast confidence. The 19 UTC NBM was downplayed today as it contains significant 12 UTC GFS/Canadian input. ...Weather/Hazards Highlights... A series of potentially strong storms are slated to effect Alaska over the next week. Expect a Bering Sea system with uncertain but favorable upper support and organized precipitation/winds to reach the mainland Friday and work inland into the interior into the weekend, but ample downstream energy transference will meanwhile increasingly focus storminess into the northern then eastern Gulf of Alaska and spread terrain enhancing precipitation into southern and especially southeast Alaska. Upstream, a potentially deep/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 unsettled conditions in earnest over much of the mainland and into the Gulf of Alaska by late weekend and through early next week. This could include enhanced wrapping precipitation and winds. Schichtel Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat, 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