Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 629 PM EDT Tue Aug 04 2020 Valid 12Z Sat Aug 08 2020 - 12Z Wed Aug 12 2020 ...Guidance Evaluation... The WPC Alaskan medium range product suite was primarily derived from a composite blend of the 12 UTC GFS/ECMWF during days 4-5 (Sat-Sun). A gradual trend toward heavier weight placed on ECENS/GEFS ensemble means was shown through time, with majority ensemble means by days 7-8 (Tue-Wed). Guidance shows a reasonably similar large scale pattern, and a relatively good consensus on many of the details during the first half of the forecast period. Detail differences become larger late in the forecast period, although relatively good agreement continued at larger scales. The described blend emphasizes some of the agreed-upon details of the forecast early in the period, and smooths out some of the differences late in the forecast period. ...Weather Highlights/Threats and Predictability... A fairly active series of low pressure system from the Bering Sea/Aleutians east across the Gulf of Alaska will keep wet conditions in place across southern mainland Alaska and Southeast Alaska through the weekend, with heavy rainfall possible. Farther north, a weakening frontal boundary and topographical effects will result in scattered convection across northern portions of the Interior as well as the Brooks Range through the weekend, gradually dwindling through early next week. In general, clouds and precipitation will keep high temperatures across much of Alaska several degrees below average, and low temperatures several degrees above average. Guidance showed some consensus that another frontal system should affect the Aleutians Mon-Tue, reaching the Alaska Peninsula and southern mainland Alaska Tue night-Wed (as the surface low crosses the southern/central Bering Sea). This system should be accompanied by another round of more widespread showers as well as potentially gusty winds. Ryan 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 rain across portions of mainland Alaska, Fri, Aug 7. - Heavy rain across portions of the Alaska Panhandle and mainland Alaska Fri-Sun, Aug 7-Aug 9. 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