Alaska Extended Forecast Discussion National Weather Service College Park MD 755 PM EDT Tue Jul 15 2025 Valid 12Z Sat 19 Jul 2025 - 12Z Wed 23 Jul 2025 ...Guidance Evaluation and Preferences... Today's model guidance shows a surprisingly excellent agreement among the ensemble mean solutions even out to Day 8 across the Alaskan domain. The ensemble means generally depict a cyclone initially centered over the western Bering Sea will grow in size and lift northeast toward the west coast of mainland Alaska by early next week. On the contrary, the spread among the deterministic model outputs grow exponentially in the direction of the cyclone track starting on Day 5. The 12Z GFS was the fastest among the deterministic guidance (which agrees very well with the consensus of the ensemble means). The rest of the determinstic outputs lag behind the ensemble consensus mean position of the cyclone by varying distances. Meanwhile, a weakly-defined omega blocking pattern is depicted across the Arctic Ocean north of mainland Alaska. An upper-level ridge is forecast to amplify somewhat and nudge eastward into eastern portion of Alaska by early next week when southwesterly flow ahead of the Bering Sea low transports increasing moisture into southwestern Alaska. The WPC medium-range forecast package begins with a 40% blend of the 12Z ECMWF/00Z EC mean, 40% from the 12Z GFS/GEFS, and 20% from the 12Z CMC/CMC mean, which quickly transistions to only comprising of the ensemble means by Day 6. ...Pattern Overview and Weather/Hazards Highlights... A triple-point low pressure wave will initially deliver a round of soaking rain across southwestern Alaska including the Peninsula early this weekend. A lull in the rain is forecast from Sunday into Monday before an increasingly wet pattern gradually overspreads southwestern Alaska and then up the west coast heading into midweek next week. Rainfall amounts are not expected to reach heavy criteria for much of these areas except perhaps the western portion of the Alaska Range by next Tuesday. Wet snow can be expected for the higher elevations. Meanwhile, scattered showers and embedded thunderstorms are expected across the central section of mainland Alaska with a better chance of seeing these activities this weekend, and especially by next Wednesday when a cold front ahead of the Bering Sea cyclone could be passing through the region. Temperatures should average above normal for the northwestern and southeastern Alaska including the Panhandle through the medium- range period. The Southwest should average slightly below normal especially when precipitation from the Bering Sea low arrives next week. 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 the remainder period for the North Slope as the high pressure system weakens ahead of the Bering Sea cyclone. 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