Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 705 PM EDT Fri May 14 2021 Valid 12Z Tue May 18 2021 - 12Z Sat May 22 2021 ...Overview... Storm track will largely stay west-to-east along ~50N during the period, with weak flow over the Interior. This will maintain a fairly quiet pattern over much of the state with showers over the Alaska Range to the Brooks Range with daytime heating (50s and 60s in the valleys) and still cool air aloft. More organized rainfall will be along parts of the Aleutians and eventually to the Panhandle late next week. ...Guidance/Predictability Assessment... Models and ensembles have been trying to capture the Pacific flow from the northern and southern sources, and waver on how to interact each of them near the Aleutians before progressing eastward. The 12Z GFS stood out apart from the ECMWF/Canadian in showing a quicker and stronger upper feature east of Kamchatka next Tue that overtakes and downstream system, but also shifting it northward into the Bering Sea. The ensembles still generally show this secondary shortwave/upper low to merge into the lead upper system and track it eastward just south of the Aleutians. This has been the preference the past few days and saw no reason to deviate with the GFS solution. Therefore, used a blend of the 12Z ECMWF/Canadian and 12Z GEFS mean/00Z ECMWF ensemble mean as a starting point. Trended toward just the ECMWF for some details by late in the period but with low confidence. This at least maintained a reasonable system progression albeit slightly different than the forecast 24 hrs ago. ...Weather/Threats Highlights... Weak troughing over the mainland will promote scattered showers (snow over higher elevations) across the Interior/North Slope through much of the week. Areas of the Panhandle may see some showers early in the week and perhaps by next weekend. A more defined system may organize around the Aleutians on the heels of a leading weakening system ~Wednesday with generally light to perhaps modest rain for the island chain. Temperatures will be within several degrees of normal over much of the state, warming into next weekend, but near to below normal over the Panhandle. Fracasso Hazards: No significant hazards are expected over Alaska during this forecast period. 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