Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 600 PM EDT Thu Oct 13 2022 Valid 12Z Mon Oct 17 2022 - 12Z Fri Oct 21 2022 ...Multi-storm heavy precipitation and high wind/wave maritime threat with impact from the Aleutians to South-central/Southeast Alaska to continue next week... ...Overview and Guidance/Predictability Assessment and Weather/Hazards Highlights... The 12 UTC GFS/ECMWF/UKMET and Canadian solutions seem well clustered Monday into Tuesday and are well supported by ensembles, bolstering forecast confidence. In this period, lingering low energies will keep the eastern Bering Sea and Western/Southwestern Alaska into the Interior unsettled with some periods of wintry precipitation and some gusty winds. Low/frontal genesis downstream into the northern Gulf of Alaska and long moisture fetch lead inflow will combine with topograhic lift enhancement to support a lingering pattern with enhanced maritime to coastal winds/waves and a multi-day heavy rainfall/runoff and elevation snowfall threats across South-central and Southeast Alaska. Expect a small break before guidance develops and tracks another deep low pressure system to work from the west Pacific back into the Gulf of Alaska by Tuesday/Wednesday in what is proving to be quite an astonding series of storms so far in October in a highly energetic pattern. However, forecast spread increases with the details/timing of this potent storm and an uncertain partial connection to current Tropical Depression 21 over the southwest Pacific. The 12 UTC GFS/GEFS are much slower to lift the storm into the Gulf of Alaska than the 12 UTC ECMWF/UKMET/Canadian and ECMWF ensembles. Given uncertainties and run to run continuity variance in the GFS/GEFS recently with this system, agreed in collaboration with Alaskan offices to maintain WPC guidance continuity with a solution closer to a composite of the 12 UTC ECMWF/UKMET/Canadian and ECMWF ensemble mean. The resultant depiction of a deep system track offers a renewed threat of stormy seas/gale winds and heavy rain/runoff and elevation snowfall threats into South-central and Southeast Alaska Tuesday/Wednesday. Meanwhile, there is also a growing guidance signal for yet another major/large low to flourish and bring widespread high winds/waves across the Bering Sea through the Aleutians into the north Pacific along with wrapping heavy rains Tuesday into next Thursday. This system would also then threaten much of West/Southwest Alaska and underneath through a stormy AKpen/Kodiak Island into the Gulf of Alaska and inland with wrapping inflow into South-central then Southeast Alaska yet again by next Wednesday-Friday with downstream potent energy transition and system progression. Schichtel Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Thu, Oct 16-Oct 20. - High winds across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Oct 18-Oct 19. - High winds across portions of mainland Alaska and the Aleutians, Tue, Oct 18. - High winds across portions of mainland Alaska, Sun, Oct 16. 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