Alaska Extended Forecast Discussion National Weather Service College Park MD 700 PM EST Mon Nov 17 2025 Valid 12Z Fri 21 Nov 2025 - 12Z Tue 25 Nov 2025 ...Synoptic Overview... During the course of the extended period, an increasingly amplified upper air pattern is forecast to establish across the Alaska domain. This pattern will begin will a cyclone gradually weakening over southwestern Alaska and the Gulf of Alaska followed an increasingly negatively-tilted upper trough moving into the Bering Sea and the Aleutians Sunday into Monday in conjunction with the establishment of a pronounced omega block across mainland Alaska into the Arctic Ocean. Meanwhile, an arctic surface high pressure system is forecast to establish across eastern mainland Alaska into the Yukon Territory. ...Guidance Evaluation/Preferences... With the increasingly amplified upper air pattern as noted, the deterministic guidance exhibits greater than normal divergence across the Alaska domain as the forecast extends into the weekend and into early next week. Nevertheless, the ensemble means from the major global models show decent agreement on this pattern evolution out to Day 8, with a solid signal for an increasingly amplified omega block sliding east into mainland Alaska by early next week. The EC ensemble mean is the most pronounced ensemble guidance compared with the GEFS mean and the CMC mean. The ensemble trend has also supported a more pronounced and amplified pattern heading into early next week for the Alaska domain. The WPC medium-range forecast package is based on the consensus blend of 40% from the 06Z/12Z GFS and 12Z GEFS, 40% from the 12Z ECMWF and 00Z EC mean, and 20% from the 12Z CMC and CMC mean, skewing markedly toward the consensus of the ensemble means on Days 7 & 8. This blend yielded solutions that are quite compatible with yesterday's WPC forecast package. ...Weather/Hazards Highlights... Impacts associated with a cyclone sliding across the Alaska Peninsula into the Gulf late this week will support the threat of high winds along the southern and southeastern coastal sections, with the South Central being the most likely location of receiving heavy precipitation on Thursday, and the Peninsula to Kodiak Island being the locations for high winds. These conditions are expected to gradually subside through the weaken as the cyclone weakens. Tight pressure gradient ahead of the next cyclone will likely bring gale to possibly storm force southeasterly winds into the Aleutians late in the weekend as the upper air pattern amplifies. The pronounced omega block establishing over mainland Alaska will block the eastward progress of the cyclone and deflect it northward into the Bering Sea. Meanwhile, an arctic high pressure system is forecast to establish over eastern mainland Alaska into the Yukon Territory this weekend into early next week under the eastern branch of the omega block, where gradually colder conditions can be expected. Otherwise, much of the remainder of Alaska will remain milder than normal. Kong 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