Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 752 PM EDT Tue Mar 28 2023 Valid 12Z Sat Apr 01 2023 - 12Z Wed Apr 05 2023 ...Overview with Guidance Evaluation/Predictability Assessment... The medium range forecast period for Alaska will begin on Saturday with a weakening cyclone sliding generally southeastward slowly away from the Gulf. Precipitation will likely be tapering off along the southern coast of Alaska on Saturday as the low moves away, while precipitation amounts for the Panhandle remain relatively light. Even though the cyclone will be slowly departing southern Alaska, models generally agree that a tight pressure gradient will be maintained near and to the east of the Alaska Peninsula into early next week. This will keep the threat of strong gap winds in place near the favored terrain of the Alaska Peninsula/Kodiak Island/Kenai Peninsula. The tight pressure gradient in this region is partially supported by a shortwave trough that is forecast to dip into the region by about Sunday. The GFS (12Z in particular) is the most aggressive in digging this trough through the Alaska Peninsula. Meanwhile, the ECMWF and CMC generally support a stronger ridge with its axis extending south into the North Pacific right behind the shortwave. The ridging scenario is better supported by the ensemble means from the EC, CMC, as well as the GEFS, although the amplitude of the GEFS ridge is dampened by the more aggressive shortwave in the GFS. Behind the upper ridge, models are showing quite a bit of spread on the low, or fragments of a cyclonic circulation, with its broad center possibly moving into the western portion of the Bering Sea by next Wednesday. We will await for the models to reach a better agreement in subsequent model runs. Precipitation in advance of this system is forecast to reach the western portion of the Aleutians during the weekend with the GFS favors a more eastern and northeastern advancement of its main axis. This is in response to a faster-moving shortwave that is forecast to move up the Aleutian Island chain and eventually push through the ridge axis near the Peninsula. This aggressive solution is not supported by the GEFS mean nor the EC and CMC deterministic and ensemble means. The WPC Alaskan forecast package begins with 40% from the 00Z/12Z EC and EC mean, 40% from the 12Z GFS and GEFS, and 20% CMC and CMC mean, transitioning to mostly a blend of the 00Z EC mean, 12Z EC, 12Z CMC mean, and 12Z GEFS by Days 7 & 8 (with no GFS included). ...Weather/Hazard Highlights... Aside from the threat of strong gap winds across the coastal sections and nearby islands off the eastern portion of the Alaska Peninsula, no significant weather concerns are forecast for the rest of Alaska. Mainly light precipitation is forecast along the Panhandle during the weekend, while a period of light snow is forecast for western Alaska with the passage of the upper shortwave. Precipitation is expected to be heavier across the western Aleutians this weekend with a gradual expansion of the precipitation coverage up the Aleutians early next week followed by less certain details by midweek. Meanwhile, northern Alaska will be milder than normal but well below hazards levels. Kong Hazards: - High winds across portions of mainland Alaska, Fri-Sun, Mar 31-Apr 2. 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