Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 535 PM EST Fri Nov 13 2020 Valid 12Z Tue Nov 17 2020 - 12Z Sat Nov 21 2020 ...Guidance/Predictability Assessment... The WPC Alaskan medium range product suite was primarily derived from a composite blend of the now more compatible 12 UTC GFS/ECMWF, 12 UTC GEFS/ECMWF ensemble means and the 19 UTC National Blend of Models days 4-8. Despite improved forecast clustering, especially with the larger scale pattern transition, recent run to run model variance seems to only suggest near average system predictability. Accordingly, inclusion in the composite of the ensemble means was intended to mitigate some model detail consistent with uncertainty. ...Weather/Threats Highlights... The transition of an amplified upper ridge from the Bering Sea to over the Interior will act to moderate temperatures there significantly by early-mid next week and lead into a more benign pattern over the region as precipitation focusing upper trough energy lifting on the western periphery of this ridge lifts through southwest then western/northwestern Alaska. Meanwhile, lead upper troughing held underneath over an unsettled eastern Gulf of Alaska and Southeast Panhandle will slowly weaken and lose influence over the area. Upstream, there is an increasing guidance signal supporting amplified upper trough/closed low development into the Bering Sea and Aleutians mid-later next week. This would bring a potentially significant threat of enhanced winds/waves and precipitation across the region, then increasingly later next week/weekend into southwest and across southern Alaska as ample upper trough and storm energies work into the Gulf of Alaska. 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: No significant hazards are expected over Alaska during this forecast period. 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