Alaska Extended Forecast Discussion National Weather Service College Park MD 612 PM EDT Sat Aug 30 2025 Valid 12Z Wed 03 Sep 2025 - 12Z Sun 07 Sep 2025 ...Into Early September Heavy Rain/Flooding/Wind Threats for Southwest/Western Alaska... ...Guidance Evaluation/Preferences... Prefer again a composite of best clustered guidance of the 12 UTC GFS/ECMWF models and GEFS/ECMWF ensemble means through medium- range time scales in pesky active flow with overall above average predictability. This plan best maintains WPC product continuity. ...Weather/Hazards Highlights... It remains generally the case that an amplified/blocky and slow to transition flow pattern over Alaska and vicinity will be highlighted by a series of potent shortwaves/surface low pressure systems primed to work through a Bering Sea/Aleutians mean upper trough to lift up into the Mainland around the periphery of Southeast Alaska to the eastern Interior mean upper ridge. This pattern will remain favorable to produce a protracted period of wet/unsettled weather expected to persist from the extended holiday weekend through much of next week. This will include a continued significant series of organized systems and long fetch atmosheric river moisture to fuel periodic and repeat chances for heavy rain and continued runoff/flooding isues from the Alaska Peninsula through the Southwest/Western Alaska and up to the west- central Brooks Range where enhanced snows are also expected. By this forecast period, the main lows to focus activity is expected to lift from the Alaska Peninsula and southeast Bristol Bay next midweek prior to shearing through the Mainland later next week. Upstream, the guidance signal is growing in support of a deeper storm track meanwhile slated to bring high winds/unsettled flow and maritime threats across the Aleutians and nearby waters. Along with maritime hazards entering the western Gulf of Alaska, this storm and potential triple-point low development may focus subsequent high wind and heavy rainfall threat impacts into the Alaskan Peninsula and then Kodiak Island and coastak SouthCentral Alaska next weekend with downstream energy translation. Meanwhile, Southeast Alaska should enjoy a pleasant week ahead overall as an upper ridge yields continued low rainfall chances and mainly benign weather as a compact closed low lifts well offshore with modest affect over the eastern Gulf of Alaska. Schichtel 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