Alaska Extended Forecast Discussion National Weather Service College Park MD 600 PM EDT Sat May 17 2025 Valid 12Z Wed 21 May 2025 - 12Z Sun 25 May 2025 ...Overview... An overall progressive pattern will rule the high latitudes next week into the weekend. Over the central Pacific, strong upper ridging will form and maintain itself south of the central Aleutians, favoring troughing into the Gulf of Alaska. For much of the state, it will be seasonable to perhaps cooler than normal with scattered showers as weaker systems move through the region, mostly over the Aleutians, coastal Southcentral, and into the Panhandle. Interior locations will see more widely scattered showers and maybe a thunderstorm. ...Guidance Evaluation and Preferences... The GFS has come around to a better handling of a lead-in shortwave over northern Kamchatka Sunday/Monday and joined the larger cluster of solutions including the 12Z ECMWF/Canadian. For the Wed-Fri period, again there was a jog quicker overall with the faster quasi-zonal flow before ridging attempts to surge northward over the western Bering Sea. However, with the strongest positive height anomalies south of the Aleutians, the trend seems to be for this northern portion of the upper ridge to be weaker/short-lived, allowing another northwestern Pacific system will push eastward through the Bering atop the upper ridge over the Pacific mid- latitudes. However, the models/ensembles kept good continuity from 24 hrs ago with the pace of this evolution. Interestingly, the ECMWF AI ensembles were even quicker to break down the brief ridging by next weekend. Altogether, a blend of the 12Z ECMWF/Canadian/GEFS mean and 00Z ECMWF ensemble mean offered a reasonable starting point. The 12Z GFS was not included as it was still offset in track of the systems through the period. ...Weather/Hazards Highlights... Weak troughing over the mainland will promote near to below normal temperatures amidst mostly cloudy skies and widespread showers with perhaps some thunder over the interior. More focused rainfall can be expected over the Aleutians with the passing systems and along the northern Gulf Coast into the Panhandle, depending on how close the parent low wobbles northward. Rainfall should be on the lighter side with any surge in mid-latitude moisture aimed into central/southern BC. Fracasso 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