Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 659 PM EDT Tue Apr 22 2025 Valid 12Z Sat 26 Apr 2025 - 12Z Wed 30 Apr 2025 ...Overview... This weekend into early next week, mean troughing is forecast atop much of the Bering Sea, with mean ridging just to the east over portions of Mainland Alasak. Spokes of the trough may poke into the state at times and support some precipitation especially along the western and southern coasts. At the surface expect a persistent gradient between a wavy Interior front and Arctic high pressure, allowing for cooler than normal temperatures in the north and warmer than normal temperatures in the south, aside from cooler coastal areas. Surface lows and frontal systems are likely to move through the northern Pacific, and one such system looks to particularly consolidate and track south of the Aleutians and Alaska Peninsula Monday-Wednesday, spreading some possibly heavier precipitation to the southern coast. ...Guidance/Predictability Assessment... Even early in the medium range period over the weekend, model guidance continues to show differences in terms of upper low positioning, the trough axis, and locations of shortwaves and surface lows. For example, by 12Z Sunday the best model consensus seems to be the 12Z ECMWF/CMC and 06Z GFS in showing a closed low north of the eastern Aleutians. However the 12Z GFS takes this energy farther south into the northern Pacific, while the UKMET shifts it quickly east. These model differences persist early in the workweek. Meanwhile some weak energy may be atop Southeast Alaska over the weekend before building ridging early next week. Then a secondary upper low looks to round the southern side of the broader trough, tracking over the northern Pacific south of the Aleutians Sunday-Tuesday and the Alaska Peninsula Tuesday- Wednesday along with a surface low. There is good model consensus for this system to exist, but continued spread in the placement. The 12Z ECMWF seemed particularly slow compared to dynamical and AI/ML model consensus with this feature and was not favored. Other deterministic models also showed some spread but in general the 12Z Tuesday position of deterministic models was a bit farther east than the ensemble means that were well clustered with the low position. The WPC forecast was based on a blend of mostly deterministic models with some EC ensemble mean component early in the forecast period. As spread increased, flipped to more than half ensemble means by Days 6-8 as the means were more agreeable. ...Weather/Hazards Highlights... Light to modest precipitation is forecast across the Alaska Peninsula to Kodiak Island and the Kenai Peninsula this weekend. Farther north, light rain and snow are possible in the western Mainland under a spoke of the upper trough. Moist inflow also should continue in southeast Alaska for light to moderate rain. Then into early next week, more focused/heavier precipitation could occur from the Alaska Peninsula into Monday and spreading into Southcentral and Southeast by Tuesday and Wednesday with the consolidating northern Pacific low pressure. Some lighter precipitation may spread into the Interior. Wind-wise, easterly winds could be breezy along the North Slope due to the Arctic surface ridge in place to the north. Winds elsewhere should be generally weak to moderate, until the possibly stronger low coming across the northern Pacific late week may enhance northwesterly gap winds behind it and southerly winds ahead of it. Cooler than normal temperatures are likely for northern Alaska into the Yukon Flats through the weekend and early next week due to persistent flow around the southeast periphery of the Arctic surface ridge. Meanwhile warmer than average temperatures are expected from the Seward Peninsula south and east through most of the rest of the Mainland, though cooler for the southern coast. Anomalies will generally be warmer for morning lows relative to those for daytime highs. Near average lows and below average highs are likely in Southeast Alaska much of the period during rounds of wet weather. Tate 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