Alaska Extended Forecast Discussion National Weather Service College Park MD 719 PM EDT Thu Jul 17 2025 Valid 12Z Mon 21 Jul 2025 - 12Z Fri 25 Jul 2025 ...Guidance Evaluation and Preferences... After a couple of days of atypical model ensemble distribution, with the mean solutions skewed toward the faster end of the distribution, a more typical model spread returns today. The consensus of the ensemble mean on the faster end of the solutions has worked out fine for placing the Bering Sea cyclone for the past couple of days. Today's guidance does show further acceleration of the Bering Sea cyclone as it reaches the eastern end of Siberia and dissipates on Days 4 and 5. The 12Z ECMWF is the fastest solution, which is faster than the 00Z EC mean and the ensemble mean consensus. Today's WPC forecast guidance for Days 4 and 5 is based on the consensus of both the deterministic and the ensemble means from the latest ECMWF/EC mean (40%), GFS/GEFS (40%), and CMC/CMC mean (20%), which yields a slightly faster solution for the Bering Sea low but with minimal changes elsewhere when comparing with yesterday's forecasts. Meanwhile, a weakly-defined omega blocking pattern initially across the Arctic Ocean north of mainland Alaska is forecast to evolve into a well-defined omega block to north of Siberia by midweek next week. Across the Alaskan domain, an upper-level ridge is forecast to amplify somewhat and nudge eastward into the eastern portion of Alaska early next week when southwesterly flow ahead of the Bering Sea low transports increasing moisture into southwestern Alaska. The WPC forecast guidance from Days 5 to 8 incorporates increasing percentages from the ensemble means. This blend yields a solution very compatible with yesterday's WPC forecast package for Alaska. ...Pattern Overview and Weather/Hazards Highlights... The medium-range period should begin with the arrival of a wet pattern as the expansive rain shield associated with the Bering Sea pushes into southwestern Alaska early next week, and then up the west coast heading into midweek next week. A cold front associated with the cyclone is forecast to traverse the entire Alaska mainland through early next week. Widespread precipitation is expected across much of mainland Alaska next week with the exception of Yukon Flats, the entire length of the southern coastal section, and the Panhandle. Rainfall amounts are not expected to reach heavy criteria for much of these areas except perhaps along the Alaska Range by next Tuesday although the model QPF amounts have decreased since yesterday. Wet snow can be expected for the higher elevations. Farther to the north, as the Bering Sea cyclone occludes and the associated cold front moves through mainland Alaska, rain and high-elevation snow are forecast to linger along the Brooks Range through much of next week. Temperatures should average above normal for the northwestern and southeastern Alaska including the Panhandle through the medium- range period. Portions of the Panhandle should feel very mild high temperatures into the 70s early next week. The Southwest should average slightly below normal especially with the arrival of precipitation from the Bering Sea cyclone followed by the passage of the cold front. The North Slope should start out below normal this weekend as a surface high pressure system in the Arctic Ocean feeds cool winds into the region. A moderating trend is forecast through early next week for the North Slope as the high pressure system weakens ahead of the Bering Sea cyclone, but a cool down can be expected once again midweek due to an increasing chance of precipitation. Kong Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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