Alaska Extended Forecast Discussion National Weather Service College Park MD 744 PM EDT Sat Sep 20 2025 Valid 12Z Wed 24 Sep 2025 - 12Z Sun 28 Sep 2025 ***Rain and wind for southern Alaska for the end of the week*** ...General Overview... A well-developed occluded surface low over the Bering Sea rapidly tracks east through Thursday, with a secondary low forming after crossing the Alaska Peninsula and becoming the dominant low over the Gulf for the end of the week. Meanwhile, an amplifying trough over eastern Siberia should support a developing surface low near the Bering Strait, and thus a cold front that could approach western Alaska by next Saturday. ...Guidance Evaluation/Preferences... The 12Z model guidance suite featured good overall synoptic scale agreement for Wednesday, and therefore a multi-deterministic model blend works well as a starting point in the forecast process. Looking ahead to the end of the week, the GFS becomes faster and much stronger with the eastern Siberia low and dives southward to the Gulf, whereas the CMC/ECMWF maintain a better clustered low solution near northwest mainland Alaska by next Saturday, which could result in even colder conditions and wintry precipitation going into next weekend across the western half of the state, so this will be something to monitor going forward. The ensemble means were gradually increased to about 60% by the end of the forecast period owing to high uncertainty across domain. ...Weather/Hazards Highlights... The next low pressure system will bring potential for hazardous weather for southern coastal areas of Alaska towards the middle to end of next week. High winds are expected along the Aleutians Tuesday through Wednesday as the system strengthens over the Bering Sea. The low could bring localized heavy rain to South- Central and Southeast Alaska on Thursday into Friday. In terms of temperatures, colder conditions will be commonplace across most of the mainland, with subfreezing overnight lows becoming more widespread across the Interior by the middle of next week. There may be a renewed surge of colder conditions by next Saturday over northwestern Alaska depending on how the low near eastern Siberia evolves, and changes to the forecast are likely. 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