Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 658 PM EDT Mon Sep 30 2024 Valid 12Z Fri Oct 04 2024 - 12Z Tue Oct 08 2024 ...High winds possible across the Aleutians and heavy rainfall likely for southern and southeast Alaska associated with a strong surface low... ...Overview... The main feature of note during the medium range period is a strong surface low expected to enter the Bering Sea later this week, and slowly slide south and east across the AK Peninsula and into the Gulf this weekend. It may linger in the Gulf for a few days as a strong ridge of high pressure builds downstream over Western Canada. This low will likely bring some impactful weather to parts of the Aleutians, Southern Coast, and Southeast with strong winds and heavy rainfall. ...Guidance Evaluation/Preferences... The latest 12Z model guidance continues to show very good agreement on this system. There are some timing differences and uncertainties in individual shortwaves rounding the base of the upper level low, but these are details that are harder to resolve at these longer time scales. This results in uncertainty in the strength/depth of the low as it moves into the Gulf as well. A blend of the deterministic guidance served as a good starting point from Friday to Sunday. After this, incorporated more of the ensemble means to help mitigate the smaller scale differences, along with moderate percentages of the ECMWF and CMC to help maintain better system definition and strength. Overall, very good continuity with yesterdays WPC forecast as well. ...Weather/Hazards Highlights... Some light rain is expected to linger into late week across southeast Alaska associated with a weaker surface low moving into the Panhandle. After this, attention then turns 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 next weekend, and then the southern coastal mountains of the mainland. Storm force winds and extremely rough seas are expected over the open waters of the Bering, with strong winds likely across the central 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 into early next week. 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. Santorelli 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