Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 703 PM EDT Fri Oct 09 2020 Valid 12Z Tue Oct 13 2020 - 12Z Sat Oct 17 2020 ...Overview and Guidance/Predictability Assessment... A blend of reasonably compatible guidance from the 12 UTC GFS/ECMWF and 12 UTC GEFS/ECMWF ensemble means was primarily used to provide a starting point for the WPC Alaskan medium range product suite. Most weighting in the blend was applied to the ECMWF Tue/Wed and then increasingly the ECMWF ensemble mean amid growing forecast spread and uncertainty. Emphasis on the ECMWF then ECMWF ensemble mean shifted the blend into the more amplified side of the full envelope of solutions for Alaska upper troughing. This collaborative solution seems prudent given high upper ridge amplitude upstream in most guidance. This maintains reasonable WPC continuity. ...Weather/Threats Highlights.. Strong upper ridge amplification is expected up through the Bering Sea to into the Arctic Ocean early next week. This should allow Arctic flow energy to carve out an amplifying downstream upper trough down over an increasingly unsettled and cooled/locally snowy North Slope and Interior through mid-later next week before the moderating main upper ridge is slated to shift eastward and inland. Guidance is still quite varied with the details of the upper troughing though, so details will emerge into shorter range time scales. This Arctic energy may also amplify sufficiently to overcome early-mid week southern stream troughing/systems over the Gulf of Alaska. Coastal areas of southern and southeast Alaska will remain unsettled/showery in this transitional pattern. The Aleutians may turn more stormy late period as new upper trough energies offer potential to work deepening systems into the region as the main upper ridge shifts eastward. 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