Alaska Extended Forecast Discussion National Weather Service College Park MD 620 PM EDT Sat Sep 27 2025 Valid 12Z Wed 01 Oct 2025 - 12Z Sun 05 Oct 2025 ...Synoptic Overview... A trough and upper low anchored around the Bering Strait will persist through about Friday, after which a much deeper longwave trough will absorb the low as it deepens and quickly amplifies over the weekend. This increasingly amplified trough will support a large and strong low that will likely deepen into the 970s mb range as it tracks across the western and northern Bering. The low will likely become cut off this weekend. For late week, shortwaves rotating around the upper low will keep conditions unsettled but highly variable across much of mainland Alaska. Once the deep trough establishes itself over the Bering and the subsequent downstream ridging establishes itself over the eastern half of the state, the weather should become much more constant...with unsettled conditions across much of the western half of the state, and ridging and more tranquil weather across the east. ...Guidance Evaluation and Preferences... Overall the guidance is in pretty good agreement on the longwave pattern, while the usual smaller details have their typical poor agreement. Given that good agreement on the larger scale, a heavier blend of deterministic guidance, particularly the foreign models was used. The 12Z GFS was the outlier going into Days 7 and 8 next weekend as its forecast with the large Bering low is to keep it far more progressive, tracking south to north along the west coast, and only getting the central pressure into the mid-980s. With typical variability, the rest of the deterministic suite was in much better agreement with a larger and slow moving 970s low establishing itself just south of the Chukotsk Peninsula into the weekend. Thus, that blend was preferred. ...Weather/Hazards Highlights... No hazardous weather is expected through Alaska for late week through the weekend. That said, there are several caveats to be mentioned. Primarily, the large and strong low expected to traverse the Bering Friday and Saturday will have some potential, if the stronger guidance verifies, to produce localized winds to storm force. This is most likely to occur when the low is rapidly strengthening as it moves north of the Western Aleutians. Thus, even with the stronger guidance, it's a low probability that those storm force winds will occur over any land areas. Needless to say however, gale force winds and rough seas are likely over much of the Bering this weekend. Another secondary potential hazard, also depending on where the large Bering low tracks, is for a period where a narrow corridor/atmospheric river scenario unfolds over the central Pacific, with the jet of moisture aimed at the Alaska Peninsula through Kodiak. Should the low and subtropical highs on either side of that moisture plume align right, then portions of the AKPen through Kodiak could see heavy rain sometime between Friday and Sunday. However, the current forecast keeps the center of the large Bering low too far north to develop much of a tropical connection, so this scenario too will need to be monitored, but appears unlikely to occur. && Wegman 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