Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 606 PM EDT Sun Apr 11 2021 Valid 12Z Thu Apr 15 2021 - 12Z Mon Apr 19 2021 ...Overview... A highly amplified/blocky flow pattern is expected later this week into early next week, especially over the mid-latitudes northward to the lower high latitudes. This will feature an upper low meandering south of Kodiak, generally between 40-50N, with ridging to its north over much of Alaska south of the Brooks Range. To the north, a shortwave will ride eastward through the Beaufort Sea and drag a cold front across the North Slope. ...Guidance/Uncertainty Assessment... The GFS paired well with the other 12Z guidance with the initial upper low drifting southward later this week. However, it continued to be likely too quick with the flow out of northeastern Russia and through the Bering into the North Slope compared to the ECMWF-led consensus. This again resulted in the GFS/GEFS becoming out of phase with the ECMWF/Canadian ensembles. Upstream pattern shows another deeper trough over Japan that will continue the amplified flow, suggesting a slower pattern overall. The GFS/GEFS have had several days of being too quick in the 5-7 day range only to trend slower within about 4 days. Preferred the 12Z ECMWF overall with support mostly from the UKMET and somewhat the Canadian (but mostly the Canadian ensembles). This maintained good continuity. ...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 shortwave and cold front 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. Temperatures will be milder than average for especially northern areas of Alaska with southwesterly flow ahead of the cold front. Parts of the Panhandle and southeastern Alaska may see near to below normal temperatures with high pressure nearby over the Yukon. 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