Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 745 PM EDT Wed Apr 05 2023 Valid 12Z Sun Apr 09 2023 - 12Z Thu Apr 13 2023 ...Overview with Guidance Evaluation/Predictability Assessment and Weather/Hazard Highlights... A cold upper low from the Arctic Ocean will likely meander over the western portion of mainland Alaska through the medium-range period under a rather blocky upper-level pattern across the Arctic. Model solutions today remain in rather good agreement on this scenario but with a split decision between sliding the weakened upper low southwest into the Bering Sea by the GFS/GEFS versus keeping the low near northwestern Alaska into the middle a next week by the ECMWF/EC mean. Dry but much colder than normal conditions can be expected for western and southwestern Alaska through the medium-range period under this meandering upper low. Occasional light snow is expected from the eastern mainland to the North Slope. Temperatures are forecast to begin recovering next Tuesday and should further moderating by next Wednesday as the upper low erodes, despite the uncertainty in its eventually track in the longer range forecasts. Meanwhile, the southern coastal and mountainous sections of Alaska will see waves of moisture arriving from the Pacific, with the Panhandle likely experiencing the peak of the moisture surge Sunday into Monday when an occluded cyclone edges toward the Gulf of Alaska from the south. The 00Z/12Z CMC today brings the low faster northward into the Gulf of Alaska and the 12Z EC means trend this way as well during this time frame. This would increase the chance of precipitation into the southern coastal sections while increasing the chance of stronger gap winds off to the east of the Alaska Peninsula. Precipitation should be heaviest farther south across the Panhandle but excessive precipitation is not expected under this modestly strong moisture plume. The next cyclone of concern appears to be moving into the western Bering Sea by about next Tuesday to Wednesday as the lead frontal system is forecast to pass through the Aleutians at a relatively quick and steady pace. Model ensemble means today remain in good agreement on the forecast evolution of this system but with a tendency to push a triple-point low faster eastward across the eastern Aleutians into the Gulf of Alaska. The speed of the front and the triple-point low will appear to limit the threat of heavy precipitation across the Aleutians although some high winds cannot be ruled out. The WPC Alaskan forecast package was based on a blend of 40% from the 12Z EC and EC mean, 40% from the 12Z GFS and GEFS, and 20% CMC and CMC mean for Days 4-6, followed by a slightly increased weights given to the ensemble means from Day 6 through Day 8. Kong Hazards: - Much below normal temperatures across portions of mainland Alaska, Sat-Tue, Apr 8-Apr 11. 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