Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 643 PM EDT Mon Apr 12 2021 Valid 12Z Fri Apr 16 2021 - 12Z Tue Apr 20 2021 ...Overview... A highly amplified/blocky flow pattern is expected later this week into early next week, forced by positive height anomalies nosing into the western Bering Sea (+2.5 sigma) and even stronger anomalies (+3 sigma) over northwestern Canada as a closed high anchors over British Columbia/Yukon. This favors an upper low in between but south of the mainland, generally south of 50N until perhaps next week. To the north, two shortwaves will ride eastward through the Beaufort Sea and each drag a cold front across the North Slope. Precipitation will generally be light over the area with abundant high pressure. ...Guidance/Uncertainty Assessment... The GFS and GEFS remained displaced and generally faster with the flow over the higher latitudes (north of ~60N) which has been ongoing for several days. Again today, favored the ECMWF/ECMWF ensembles which were generally slower and more amplified along with the UKMET and Canadian/Canadian ensembles at times. Multi-day trend has shown the GFS gradually slowing down toward the ongoing ECMWF idea but with expected shufflings of the players. Trend with the upper low south of the Gulf and wound-up occluded front has been a bit farther north but it will still be fighting strong ridging to its north/northeast. A future player could be a tropical cyclone in the western Pacific that may recurve off Japan per the ensemble guidance next week. ...Weather/Hazards Highlights... With the main system south of the mainland, precipitation will be generally light over the state. Relatively modest precipitation is expected over northern areas as the initial and second shortwave and cold fronts push across the North Slope. Some enhancement is possible on the western side of the Brooks Range, northeast of Kotzebue. As the Pacific upper low and occluded front drift back northward early next week, some rain may try to push toward the Panhandle and Southcentral (especially Kodiak and the southern Kenai peninsula) but would likely be light. Temperatures will be milder than average for especially northern areas of Alaska with southwesterly to westerly flow ahead of the cold front and well above normal 850mb temperatures. Parts of the Panhandle and southeastern Alaska may see near to below normal temperatures with high pressure nearby over the Yukon despite a surge of warmth aloft. Fracasso 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