Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 751 PM EDT Sun Oct 2 2022 Valid 12Z Thu Oct 6 2022 - 12Z Mon Oct 10 2022 ...Synoptic Overview... The extended forecast period begins on Thursday with an upper level ridge axis centered across the south-central portion of the state with above normal temperatures across much of the state. The deep upper low initially over the Gulf will continue to slowly drop southward and away from the Alaska domain. Meanwhile, a major storm system brushes past the northwestern coast, with the core of the storm expected to pass well to the northwest of the state. The trailing cold front will likely result in a cooling trend going into the weekend, and a deep surge of moisture with heavy coastal precipitation can be expected for parts of the southern coast. ...Guidance/Predictability Assessment... The 12Z model guidance suite depicts good overall synoptic scale agreement across the Alaska domain late in the week, with the deep closed low slowly moving south over the Gulf/North Pacific, and a ridge axis across southern Alaska that weakens. The CMC begins to deviate from the model consensus going into Saturday with a amplifying trough over the eastern Aleutians and Alaska Peninsula, and farther west than the weaker GFS/ECMWF solutions. This is even more apparent by next Monday across the mainland with the CMC trough out of phase with the GFS/ECMWF ridge axis in the same general area. The GFS is beginning to show a potentially strong trough approaching the central Aleutians by early next week. Overall, a multi-deterministic model blend suffices as a starting point through Friday, and then gradually increase the ensemble means going into next weekend and then removing the CMC to account for greater forecast uncertainty. ...Weather/Hazards Highlights... The main weather story going into next weekend will be the increasing rain and mountain snow prospects for the southern coastal areas of Alaska and western portions of the southeast Panhandle region, where several inches of liquid equivalent is likely for the topographically favored terrain, as moisture from the Gulf flows northward ahead of a developing surface low near the Kenai Peninsula. More rain is probable for parts of the Aleutians Sunday and next Monday as the next storm system develops in this region. Farther north across the Interior, isolated to scattered showers are likely ahead of the cold front, and snow for the Brooks Range as temperatures return to more seasonal levels. This will be in contrast to the pleasantly warm conditions for the middle of the week, with highs running 10-20 degrees above normal in many cases. 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