Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 624 PM EDT Tue Apr 06 2021 Valid 12Z Sat Apr 10 2021 - 12Z Wed Apr 14 2021 ...A cold pattern for Alaska with deep maritime storms... ...Guidance/Uncertainty Assessment... The latest models and ensembles indicate an amplified large scale pattern this weekend aloft, with a cold trough over eastern Alaska and the Yukon on Saturday. A shallow ridge is expected to gradually build across the mainland through Monday by ample but still uncertain upper trough shortwaves that feed back into the Bering Sea. Model solutions are relatively well clustered through the weekend before more becoming more significant for the Monday through Wednesday time period, especially across the North Pacific. Recent runs of the ECMWF/CMC/JMA remain better aligned with ensembles than the GFS. This is mainly evident with system and flow transition and progression from the Bering Sea/Aleutians to the mainland and Gulf of Alaska. Accordingly, the WPC Alaskan product suite was primarily derived from a blend of the 12Z GFS/ECMWF/CMC through Sunday, and the 12Z ECMWF/CMC and the GEFS/ECMWF ensemble means for early next week amid growing forecast spread. ...Weather/Hazards Highlights... Old Man Winter will main strong control over the weather pattern across the Alaska domain this weekend and into early next week. The arctic air mass, courtesy of a strong surface high and deep upper trough north of the Arctic Coast, will result in readings on the order of 15 to perhaps 30 degrees below early April averages, with the potential for a few daily records lows to be challenged early in the period. A moderation trend should commence by the middle of next week. In the precipitation department, very heavy rain and mountain snow is expected to make weather headlines from the Kenai Peninsula to the southeast panhandle region. Multiple shortwave disturbances pivoting around a broad upper level gyre over the Fox Islands/eastern Bering will result in enhanced onshore flow across this region. The potential exists for several inches of QPF here, and one or more atmospheric rivers could set up and result in some minor flooding of low lying areas near the coast. Hamrick Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon-Tue, Apr 12-Apr 13. - Much below normal temperatures across portions of mainland Alaska, Fri-Sun, Apr 9-Apr 11. 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