Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 614 PM EDT Mon Sep 21 2020 Valid 12Z Fri Sep 25 2020 - 12Z Tue Sep 29 2020 ...Overview and Guidance/Predictability Assessment... One upper low rotating south of the region will drive a surface low into the Gulf and northward towards the southern coast next weekend into early next week. Another upper low drops through the Bering Strait next Friday, eventually establishing mean troughing over much of the state by early next week. Finally, the next storm enters the picture by day 8/Tuesday with a deepening surface low/frontal system just south of the Western Aleutians. There is decent agreement in the models on the overall large scale pattern, especially days 4-5. After that, there remains question on the details of the surface low in the Gulf as it drifts northward/weakens and also with a shortwave rotating underneath the broader Alaska trough, well south of the region. With this, the WPC blend was based on a majority 12z GFS/ECMWF compromise days 4-5, with increasing usage of the ensemble means (00z ECENS/12z GEFS) thereafter to sort out detail uncertainties. The next storm system entering the western Aleutians late period actually has good agreement between the 12z GFS/ECMWF, so opted to maintain some of the deterministic run as late as day 8 to help maintain a meaningful surface low. ...Weather/Threats Highlights... Heavy rainfall is possible along the Southern Coast into parts of the Panhandle region associated with the surface low entering the Gulf and a frontal boundary lingering for a few days. Some snow may fall in the higher elevations. Rainfall should wane as the surface low weakens, but another low lifting towards the region may bring renewed moderate to locally heavy precip late period, especially for the Panhandle region. Rainfall/unsettled conditions should be on the increase by early next week across parts of the Western Aleutians as the next storm system moves eastward into the region. Mean troughing over much of the state, should keep temperatures near or below normal for much of Alaska. Santorelli 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 and mainland Alaska, Fri-Sat, Sep 25-Sep 26. 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