Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 658 PM EDT Thu Mar 26 2020 Valid 12Z Mon Mar 30 2020 - 12Z Fri Apr 03 2020 ...Below to much below normal temperatures to continue over parts of Alaska into next week... An anomalous upper-level high centered across northwest mainland Alaska early next week will displace arctic air southward to its east, keeping much of mainland Alaska cold through much of the week. High temperatures Mon-Wed are forecast to be 10-25 deg F below average across the southern half of mainland Alaska, as well as much of Southeast Alaska, with the arctic air mass expected to reinforce a persistent stationary frontal boundary just offshore. The North Slope will be the significant exception, where above normal temperatures are forecast through the medium range. Ensemble show a general consensus that the upper ridge should gradually weaken as it shifts eastward through the middle of next week, eventually breaking down the strong arctic connection and allowing temperatures across Alaska to slowly warm. Surface high pressure across mainland Alaska should keep conditions dry for many areas, while a relatively active storm track across the North Pacific remains well south of mainland Alaska, with some potential precipitation for the Aleutians, the Alaska Peninsula, and perhaps southwestern mainland Alaska. Models/ensembles show some modest consensus on the idea of a deeper low pressure system moving into the Bering Sea next Thu-Fri, with a potential pattern change in the works for Alaska, as the removal of the blocking ridge present earlier in the week potentially opens Alaska up to somewhat more progressive westerly mid/upper-level flow (and warming temperatures) The WPC forecast was initially based heavily on the 12Z ECMWF, along with some use of the GEFS/NAEFS ensemble means, during days 4-5 (Mon-Tue). The ECMWF made a significant adjustment from its previous run, with the 00Z run representing an outlier in terms of the overall model/ensemble consensus, and the 12Z run falling into line. During days 6-8 (Wed-Fri), majority forecast weighting was shifted to the GEFS/NAEFS ensemble means, with some continued use of the deterministic ECMWF through the end of the forecast period. Ryan Hazards: -High winds across portions of the Alaska Panhandle, mainland Alaska, and the Aleutians, Sun-Mon, Mar 29-Mar 30. -Much below normal temperatures across portions of mainland Alaska, Sun-Wed, Mar 29-Apr 1. Additional 3-7 Day Hazard information can be found on the WPC medium range hazards 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