Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 202 PM EDT Sun Aug 04 2019 Valid 12Z Thu Aug 08 2019 - 12Z Mon Aug 12 2019 ...Guidance/Predictability Assessment and Weather/Threats Highlights... The latest models and ensembles still show an overall blocky medium range flow pattern over Alaska and vicinity anchored by an amplified/stablizing ridge extending from the eastern Bering Sea and Western Alaska down through the Alaksan Peninsula and far western Gulf of Alaska. Guidance is generally well clustered into Thursday and a composite solution seems reasonable. However, significant forecast track/emphasis spread and run to run variances with a series of embedded weather focusing systems working around this feature again become especially evident days 5-8. Given uncertainty, a compatable 12 UTC GEFS mean and 00 UTC ECMWF ensemble mean blend is preferred over more varied deterministic model gudiance. The forecast strategy was, as always, collaborated with local Alaskan WFOs. In this pattern, an amplified upper level trough and surface low/system is slated for an uncertain lift over the Bering Sea into Thu-Fri on the western periphery of the main ridge. Organized precipitation through the Bering Sea and Aleutians weakens into western Alaska. More amplified upper trough development may reach the western Bering Sea by next weekend with deeper surface low/frontal genesis, with eastward progression slowed by the resilient main ridge. Well downstream, a series of mid-upper level trough energies to round the top then dig southeastward to the lee of the ridge over the interior then Southeast Panhandle. Expect reinforcement of a cool and showery pattern focused by modest but renewing northeast Gulf of Alaska surface system developments. 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