Alaska Extended Forecast Discussion National Weather Service College Park MD 657 PM EDT Mon Sep 15 2025 Valid 12Z Fri 19 Sep 2025 - 12Z Tue 23 Sep 2025 ***Periods of heavy rain and gale force winds expected from the Kenai Peninsula to Southeast Alaska*** ...General Overview... A rather unsettled weather pattern is forecast across southern Alaska and the Panhandle region as a broad upper level low becomes anchored in place across the northern Gulf by the weekend. Multiple shortwave impulses are expected to pivot around the southern and eastern periphery of that low and bring multiple rounds of rain and gusty winds. This will likely have some staying power going into early next week as well. A cold front is expected to slowly sink south across the mainland and bring a steady cooling trend over the next week. ...Guidance Evaluation/Preferences... The 12Z model guidance suite initially has a good overall depiction on the overall weather pattern across the domain for the end of this week. However, the CMC is generally slower with a shortwave tracking south of the Aleutians and Alaska Peninsula on Friday, and the ECMWF stronger with a low that develops south of Kodiak Island on Saturday. The UKMET shows a much stronger low racing across the north Pacific through Saturday, so this model solution appears to have the least ensemble support. All of the guidance agrees well in having a broad upper low and associated surface low idling over the northern Gulf by this weekend. Looking ahead to early next week, the GFS becomes more amplified with a trough over the Bering Sea region compared to the model consensus, and then it reaches the Gulf by Tuesday. With the next Bering/Aleutians low on the horizon for next Tuesday, the CMC is north of the consensus, whereas the GFS is to the south, so the ensemble means are ideal here. A general deterministic model blend suffices as a good starting point for Friday, and then the ensemble means were gradually increased to about half by next Tuesday. ...Weather/Hazards Highlights... Several inches of rainfall are likely from the eastern Kenai Peninsula to Southeast Alaska as multiple surges of moisture move into the region, with the highest totals across the windward terrain from the St. Elias Mountains to near Sitka. Strong winds of gale force are likely for the near shore waters owing to enhancement of the coastal barrier jet for these same general areas, with the highest winds expected on the 18th and the morning of the 19th. High winds are also possible for the inland waterways of Southeast Alaska as the low approaches. In terms of temperatures, a gradual cooling trend is expected to commence across the mainland as a polar front slowly sinks southward throughout the period, with some subfreezing overnight lows likely north of the Brooks Range. 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