Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 740 PM EDT Sun Aug 28 2022 Valid 12Z Thu Sep 1 2022 - 12Z Mon Sep 5 2022 ...General Overview... An active weather pattern is expected across the Alaska domain for the beginning of September, particularly across the southern mainland and across the southeast panhandle region with an onslaught of Pacific moisture surging inland. A strong storm system crossing the Bering will weaken as it tracks southeast across western Alaska, and then redevelops as a triple point low across the northern Gulf of Alaska. Heavy rainfall and potential flooding will continue to make weather headlines from the Kenai Peninsula/Anchorage eastward to the southeast Panhandle region. ...Guidance/Predictability Assessment... Models and ensembles have a good overall depiction on the strong low pressure system reaching western Alaska by Thursday, and the GFS is more in line with the model consensus in terms of strength compared to its earlier weaker runs. As the main gyre settles southward across the northern Gulf region, timing differences become apparent with individual shortwaves pivoting around it, while the main trough axis remains in decent agreement. A general deterministic blend through Friday works as a starting point in the forecast process. Going into next weekend, models differ on a wave developing along the front just south of the Aleutians, with the CMC more out of phase here compared to the GFS/ECMWF, and also on a weak upper ridge axis trying to build in across the Interior. A gradual increase in the GEFS/EC means works well for the Sunday and Monday time period. ...Sensible Weather and Potential Hazards... Multiple rounds of moderate to heavy rainfall are expected from the Kenai Peninsula and greater Anchorage area to the southeast Panhandle region. Expected rainfall totals have increased between Anchorage and the St. Elias Mountains compared to yesterday's forecast, with generally 3-6 inches likely with isolated higher totals for the Thursday through Saturday time period. The atmospheric river then gradually shifts eastward and brings another sustained period of moderate to locally heavy rain for the Panhandle over the weekend with several inches of additional rain likely across the favored terrain. Anomalous moisture flux oriented nearly orthogonal to the terrain will likely lead to daily 1-2 inch rainfall maxima, and this could lead to flooding and enhanced runoff concerns. Elsewhere across the state, isolated to scattered showers are possible each day, mainly across central and southern portions of the mainland. In terms of temperatures, readings are expected to range from the 50s across western Alaska and the southern coastal areas, and mainly 60s for the lower elevations of the eastern Interior. Hamrick 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