Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 657 PM EDT Fri Oct 14 2022 Valid 12Z Tue Oct 18 2022 - 12Z Sat Oct 22 2022 ...Major storms offer a heavy precipitation and high wind/wave maritime threat with impact from the Aleutians through South-central/Southeast Alaska next week... ...Overview and Guidance/Predictability Assessment and Weather/Hazards Highlights... The 12 UTC GFS/ECMWF/UKMET/Canadian model solutions seem well clustered Tuesday into Wednesday and are well supported by ensembles, bolstering forecast confidence. In this period, lingering low energies into this period will keep the eastern Bering Sea and Western/Southwestern Alaska into the Interior unsettled with some periods of wintry precipitation and some gusty winds. The big story to highlight is that this guidance now more uniformly develops and tracks a major/deep low with central pressure dropping near 950mb into the Gulf of Alaska Tuesday/Wednesday in what is proving to be quite an astounding series of storms so far in October in a highly energetic pattern. Forecast spread/uncertainty has significantly decreased with this potent storm, albeit still with an uncertain connection to current Tropical Storm Twentyone and more directly with JTWC invest area 91W over the west Pacific. The GFS/GEFS that were much slower to lift the storm into the Gulf of Alaska have now trending strongly more in line with recent runs of the ECMWF/UKMET/Canadian and ECMWF ensembles. The resultant composite depiction of a dangerous system track offers a significant renewed threat of stormy seas/winds, heavy rain/runoff issues and elevation snowfall threats into South-central and Southeast Alaska Tuesday/Wednesday given long fetch moisture connection and ample upper low/trough support. 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 in a broader mean circulation Tuesday into next Saturday. The details and embedded low interactions with flow is less certain, lending preference from a composite blend of the 12 UTC GFS/ECMWF increasingly over time toward the more compatible and run to run consistent 12 UTC GEFS/ECMWF ensemble means. This overall 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 Wednesday into next Friday/Saturday with downstream potent energy transition and system progression. Schichtel Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Fri, Oct 17-Oct 21. - High winds across portions of the Alaska Panhandle, mainland Alaska, and the Aleutians, Tue-Wed, Oct 18-Oct 19. - High significant wave heights for coastal portions of northern mainland Alaska, Mon, Oct 17. 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