Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 739 PM EDT Mon May 16 2022 Valid 12Z Fri May 20 2022 - 12Z Tue May 24 2022 ...Overview and Guidance/Predictability Assessment... An upper level rex block pattern will likely be in place across western Alaska and the Aleutians for the end of the week, and this will gradually break down going into next weekend and beyond. By Saturday, the upper high slowly retrogrades west across the Bering and an upper trough and cold front from the Arctic tries to build in across eastern Alaska by Sunday and into Monday. Meanwhile, and organized low pressure system develops over the North Pacific, but it is currently not expected to make much progress towards the southern Alaska coast through the weekend. The 12Z model guidance suite is in good synoptic scale agreement across much Alaska and vicinity through the end of the work week and into Saturday. There has also been improving model agreement on an amplifying upper trough over the North Slope and Arctic Coast region by the weekend. However, model spread becomes noticeable by early next week as the block pattern breaks down. The WPC forecast was primarily derived from a multi-deterministic model blend through Saturday night, with slightly greater weighting towards the ECMWF/CMC solutions, and then a gradual increase in the GEFS/ECENS for Sunday through Tuesday whilst still maintaining some of the deterministic guidance. ...Weather and Hazard Highlights... Central and northern portions of the mainland are expected to remain dry through early next week as high pressure governs the weather pattern. Rain associated with the low pressure system over the North Pacific will likely affect the central and eastern Aleutians for Friday and into Saturday, but not expected to be heavy. Some showers are also likely for the southeast Panhandle for Sunday and into Monday with onshore flow ahead of the next storm system, with mainly light to moderate amounts anticipated. However, the main threat should continue to be river flooding associated with snow melt and ice jams. Temperatures across much of the mainland are forecast to moderate going into the end of the week and the weekend, with parts of western and central Alaska likely having above normal highs with some readings in the lower 70s possible. However, a cold front sinking southward across the northeastern part of the state by next weekend will likely bring a return to colder weather for that region. Hamrick Hazards: River flooding across portions of south-central Alaska, Thu-Mon, May 19-23. 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