Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 556 PM EDT Tue Oct 01 2024 Valid 12Z Sat Oct 05 2024 - 12Z Wed Oct 09 2024 ...Dangerous Extratropical Storm associated with former West Pacific Typhoon Jebi to offer a High Wind/Wave Threat for the Bering Sea and Gulf of Alaska and a multi-day Heavy Precipitation and Runoff Threat into Southern and Southeast Alaska Friday through next Tuesday... ...Overview and Guidance Evaluation/Preferences... Guidance continues to highlight development of a major storm for maritime interests from the Bering Sea to the Gulf of Alaska later this week into next with main inland impacts expected over Southern and Southeast Alaska. This will be a deep extratropical low associated with former West Pacific Typhoon Jebi and a tap to deep moisture. Prefer reasonably clustered guidance of the 12 UTC GFS/ECMWF/UKMET/Canadian valid for this weekend. Opted to pivot to most consistent 12 UTC ECMWF/NAEFS ensemble means valid for early to mid next week. These guidance choices offer good detail consistent with above normal system predictability and WPC product continuity. Manual adjustments were applied to ensure sufficient system depth given closed upper trough support and tropical origin. ...Weather/Hazards Highlights... Attention will focus to a large and deeper storm system entering the Bering Sea region later in the week, with increasing rain chances along the West Coast and through the Aleutians into the weekend, and then through the southern coastal mountains of the mainland. Storm force winds and extremely rough seas are expected over the open waters of the Bering Sea and into the Gulf of Alaska, with strong winds likely across the Aleutians and into the AK Peninsula region as well, with gap wind enhancement. Heavy rainfall (and snow in the higher terrain) is possible across the southern Coast to Panhandle this coming weekend, with lingering inflow and focus into early-mid next week over moistened soils of Southeast Alaska terrain as guidance lingers the main low and redevelopments offshore over the unsettled Gulf of Alaska. In terms of temperatures, cooler than normal highs are likely over southern parts of Alaska and warmer than normal temperatures are likely for the northern two-thirds of the Mainland during the period, with an overall warming trend through the weekend owing to increased southerly flow ahead of the Bering Sea low pressure system. Schichtel 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