Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 609 PM EDT Mon Oct 12 2020 Valid 12Z Fri Oct 16 2020 - 12Z Tue Oct 20 2020 ...Guidance/Predictability Assessment... The 12 UTC models seemed compatible day4/Friday and used a blend of the 12 UTC GFS/ECMWF. Despite a reasonably similar larger scale pattern aloft through much of rest of the medium range period, differences with offshore surface systems grow quite rapidly over time, lowering forecast confidence. The WPC Alaskan medium range product suite was accordingly derived from a more compatible composite blend of the 12 UTC GEFS/ECMWF ensemble means and the 19 UTC National Blend of Models days 5-8. This strategy maintained good WPC product continuity. ...Weather/Threats Highlights.. An amplified upper ridge over the Bering Sea will shift eastward to the Interior Friday/weekend to stabilize/moderate. Lead Arctic system energy digs through the Southeast Panhandle Thursday/Friday and produce a swath of heavy precipitation. Meanwhile, forecast spread is relatively low and guidance supports unsettled conditions for the Aleutians heading into the weekend and into early next week as amplified upper trough energies work frontal systems over the area. Forecast confidence decreases over time downstream with subsequent interactions with lead flow/system details into the Gulf of Alaska and toward southern/southeastern coastal areas in an overall wet pattern as the aforementioned and amplified Interior upper ridge continues to shift eastward into western Canada. 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: - Heavy precipitation across portions of the Alaska Panhandle, Thu, Oct 15. 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