Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 629 PM EDT Tue Aug 24 2021 Valid 12Z Sat Aug 28 2021 - 12Z Wed Sep 01 2021 ...Guidance/Predictability Evaluation... The WPC Alaskan medium range product suite was primarily derived from a general blend of the 12Z GFS/ECMWF/CMC/WPC continuity for the first half of the forecast period, and then generally the GFS/ECMWF and their respective ensemble means for the second half of the forecast period owing to growing model forecast spread and uncertainty. ...Pattern Overview and Weather/Threats Highlights... Upper level shortwaves interacting with an arctic frontal boundary will likely support organized precipitation across portions of northern and Interior Alaska. In particular, an organized low pressure system tracking to the north of the North Slope by Friday will bring increased chances for enhanced precipitation inland across the North Slope/Brooks Range and the eastern Interior. Additional shortwave energy rotating down from the Arctic Ocean will also favor organized precipitation over the northern half of the state into the weekend. This pattern supports colder than normal temperatures down across much of the state. Meanwhile to the south, an energetic system will track across the northeastern Gulf on Saturday, and this system will bring the potential for windy conditions with some enhanced weekend precipitation for portions of Southeast Alaska, particularly across the Panhandle region. Upstream, there is much more uncertainty with system development and progression days 6-8 for Pacific systems moving across the Aleutians/Bering Sea. Schichtel/Hamrick Hazards: - High winds across portions of mainland Alaska, Fri-Sat, Aug 27-Aug 28. - Much below normal temperatures across portions of mainland Alaska, Fri-Sat, Aug 27-Aug 28. - High significant wave heights for coastal portions of mainland Alaska, Fri-Sat, Aug 27-Aug 28. - Heavy rain across portions of the Alaska Panhandle, Sat-Sun, Aug 28-Aug 29. Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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