Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 735 PM EDT Mon Apr 24 2023 Valid 12Z Fri Apr 28 2023 - 12Z Tue May 2 2023 ...Synoptic Overview... A strong upper low is forecast to slowly drop southward across the Bering Sea through the end of the week and then settle near the central Aleutians by Sunday. Meanwhile, a separate low pressure system from the central Pacific is expected to track towards the Gulf of Alaska and reach the general vicinity of the southeast Panhandle region by Sunday and weakening going into Monday. Upper level ridging will build in across western Canada and into far eastern Alaska ahead of the approaching Gulf low, and a separate ridge axis begins developing across the central Gulf early next week between the Aleutians low and the Panhandle low. ...Guidance Evaluation/Predictability Assessment... The models and ensembles have come into better synoptic scale agreement across the Alaska domain compared to yesterday for the Friday and weekend time period. For the storm system approaching the eastern Gulf, the CMC is slightly slower in bringing the low towards the southeast Panhandle, whereas the GFS and ECMWF are now close and a compromise of those two models works well as a starting point. For the upper low dropping south towards the Aleutians, there are some latitudinal differences with the core of the low, and some timing differences with shortwave energy pivoting around the southern periphery of that low. Use of the ensemble means increased to about 40-50% for early next week owing to the differences noted over the North Pacific. ...Weather/Hazard Highlights... For the end of the week as the mid to upper cyclone drops slowly across the Bering Sea, the overall flow will become more southerly into south-central mainland Alaska and result in sustained onshore flow, which will support periods of moderate to locally heavy rainfall particularly across the terrain of south-central Alaska Friday into next weekend. This onshore moisture flux will also modify the cold air mass inland with highs reaching 45-55 degrees for many inland areas. Local liquid equivalent precipitation amounts in the 3-6 inch range in orographically favored locations remain in the forecast. The remainder of southern Alaska should remain unsettled overall as assorted cyclones impact the southeast Panhandle and the Alaska Peninsula. The various low pressure systems should lead to periods of gale force winds, with the possibility of some storm force gusts, across portions of the Gulf of Alaska and Bering Sea. The northern coast of Alaska also has the threat of gales late week into the weekend as the pressure gradient tightens over the region. Hamrick 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