Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 759 PM EDT Tue Mar 10 2020 Valid 12Z Sat Mar 14 2020 - 12Z Wed Mar 18 2020 ...Overview and Guidance/Predictability Assessment... The forecast period begins on Saturday with an impressive upper level ridge and surface high anchored over the northern Gulf of Alaska, and should persist through the weekend. A storm system south of the central Aleutians will begin to erode the ridge some by early next week with the greatest height anomalies shunted southward, and the models are still have difficulty resolving the eventual track and evolution of that surface low and thus its impacts on the Aleutians. The 12Z UKMET was a northern outlier by Day 4 and did not appear to be a plausible solution, so it was not incorporated into the forecast. This is noted to a lesser degree with the 18Z GFS, and the ensemble means support a solution closer to the CMC and ECMWF that are more suppressed and eventual evolve into an open wave. By Tuesday the models are indicating the potential for a strong low pressure system to approach the western Aleutians and potentially affect the Bering Sea region by Wednesday. Given that the GFS, ECMWF, and CMC all indicate sub-970 mb lows by 12Z Wednesday, along with good ensemble support, it is reasonable to expect that this will be the next major storm system to eventually affect the Alaska domain. The main uncertainties exist with latitudinal placement, with the CMC south of the GFS/ECMWF and the ensemble means, and the GFS and ECMWF somewhat slower than the ensemble means. There will also be a weaker storm tracking north of the Arctic Coast early next week, with the latest GFS suggesting a more northward trajectory and the CMC more progressive. ...Weather Highlights/Threats... Western Alaska appears to be most favored for above normal precipitation for this time period as moisture advects northward around the western side of the large high pressure ridge, with several inches of snow likely for northwest portions of the state this weekend. Much of the central and eastern Interior, and extending to the Panhandle region, should be mainly dry during this time. The other story will be the above normal temperatures across inland sections of the state owing to the strong upper level ridge in place. Hamrick 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 Hazards: - Heavy snow across portions of northwest mainland Alaska, Fri-Sat, Mar 13-Mar 14. - Much above normal temperatures across portions of northern mainland Alaska, Fri-Tue, Mar 13-Mar 17. - Much above normal temperatures across portions of central mainland Alaska, Sat-Tue, Mar 14-Mar 17. - Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, Fri-Sat, Mar 13-Mar 14. 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