Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 732 PM EDT Sun Oct 10 2021 Valid 12Z Thu Oct 14 2021 - 12Z Mon Oct 18 2021 ...Stormy Pattern Continues from the Aleutians through Southern and Southeast Alaska... ... Guidance and Predictability Assessment... The latest models and ensemble guidance over Alaska shows above average agreement on the synoptic pattern as multiple low pressure systems moving from the Bering Sea into the Gulf of Alaska continue a stormy pattern. Models continue to show some timing and detail differences, but nothing atypical for these time ranges. The WPC Alaskan medium range product suite used the 12z GFS and ECMWF deterministic models blended with their respective ensemble means. More deterministic weighting was given during the early periods with higher predictability, with slightly more weighting towards the ensembles by the end of the period. This approach maintains good continuity with yesterdays WPC forecast. ...Pattern Overview and Weather/Hazard Highlights... An energetic and progressive flow aloft will support multiple surface low pressure systems affecting portions of Alaska late this week and into early next week. An initial strong low pressure system will exit the eastern Gulf of Alaska by mid-late next week as additional energies working from an unsettled Bering Sea and Southwest Alaska/AKPen will act to reinforce mean low pressure over the Gulf through the weekend. This should preserve a favorable moisture and enhanced precipitation pattern for southern and southeast Alaska. Upstream flow is then expected to drive a deep storm into the Bering Sea by next weekend with downstream energy transfer allowing for triple point low developments which should work across the eastern/central Aleutians and the AKPen region and eventually into the Gulf of Alaska by next Monday. This should again bring a coastal and maritime threat for heavy rainfall and gusty winds to the Aleutians this weekend and the southern coast/Alaskan Panhandle by early next week. There remains some differences in exact placement of this low as it gets into the Gulf, which of course would impact precipitation amounts along the coast and also how far inland the precipitation shield extends. 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