Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 641 PM EDT Sat Aug 01 2020 Valid 12Z Wed Aug 05 2020 - 12Z Sun Aug 09 2020 ...A Stormy Pattern for Alaska... ...Guidance Evaluation... The WPC Alaskan medium range product suite was primarily derived from a composite blend of now well clustered guidance from the 12 UTC GFS/ECMWF/Canadian and the 19 UTC National Blend of Models days 4-8. Convergence of these guidance pieces toward a more common solution bolsters forecast confidence for this period, but growing forecast spread day 7/8 suggests continued uncertainty with smaller scale system specifics. This solution reasonably good WPC continuity. ...Weather Highlights/Threats and Predictability... A deepened surface low under a supporting closed upper low/trough over the Northern Gulf of Alaska into midweek will fill over the eastern Gulf into Thursday. Wrapping moisture and rain into southern/southeast Alaska will also presents a maritime hazard over the Gulf of Alaska. Upstream, guidance has really come together compared over the past two days in depiction of a deep surface low and closed upper low/trough to develop and work into the Southern Bering Sea/Aleutians by midweek. This powerful low will progress into Bristol Bay, Southwest/Western Alaska and the Alaskan Peninsula into Thursday, then fill into the Interior over the next few days. Ample energy will meanwhile transfer downstream into unsettled northern Gulf of Alaska waters next Friday into next weekend. This system offers potential for enhanced wind/waves and rains along the broad track, then downstream into southern/southeast Alaska. There also seems to be an emerging guidance signal in the models to develop a third low that may develop just to the south of the Aleutians into Friday then downstream into the northern Gulf of Alaska over the weekend. There is substantial uncertainty with this system, but given lead storm track trends it seems widespread rain, wind and waves may present yet again. 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 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