Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 759 PM EDT Fri Sep 30 2022 Valid 12Z Tue Oct 4 2022 - 12Z Sat Oct 8 2022 ...Synoptic Overview... The extended forecast period begins on Tuesday with an amplifying upper trough over the Gulf of Alaska with a downstream ridge axis over southeast Alaska and western Canada. The trough should evolve into a nearly stationary upper low with a few surface lows associated with it, and then another strong trough approaches western Alaska by the end of the week with a deep low lifting north towards the Arctic. This will likely lead to a pattern change across much of the central and western mainland to close out the week. ...Guidance/Predictability Assessment... The 12Z model guidance suite depicts good overall synoptic scale agreement with the deep trough that evolves into a closed low over the Gulf, with the ECMWF/CMC and to a lesser degree the GFS depicting a dual upper low structure through Thursday over the Gulf. The ECMWF is stronger with a lead shortwave trough crossing the mainland Wednesday into early Thursday compared to the model consensus. A stronger disturbance approaching the Bering from Siberia is also reflected well in the guidance, with the ECMWF slightly south with the track of the surface low, whereas the CMC/GFS are stronger and a little farther north. By the end of the week, the GFS is much stronger with a trailing storm system over the Aleutians that has less in the way of ensemble support. Overall, the guidance appears more agreeable than yesterday, and therefore a multi-deterministic model blend suffices as a starting point through mid-week, and then gradually increase the ensemble means going into Friday and next Saturday. ...Weather/Hazards Highlights... Light to moderate precipitation is expected from the eastern Aleutians and the Alaska Peninsula along with perhaps some light showers across the western side of the state on Tuesday in association with the upper trough and occluded front. Increased moisture inflow and the lingering low pressure system in the northern Pacific for the latter half of the week could enhance precipitation across the south-central portion of the state and possibly into the Panhandle region. Coverage of light to moderate precipitation will likely increase across Interior Alaska Thursday and Friday ahead of the next upper trough approaching from Siberia. The likely strong surface low could lead to the potential for high winds for the northwestern interior, particularly along the coast. Temperatures are generally expected to be above normal for most areas next week. Hamrick Hazards: - Heavy precipitation across portions of the Alaska Panhandle and southern mainland Alaska, Fri, Oct 7. - High winds across portions of mainland Alaska, Thu-Fri, Oct 6-7. 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