Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 655 PM EDT Thu Jul 22 2021 Valid 12Z Mon Jul 26 2021 - 12Z Fri Jul 30 2021 ...Guidance/Predictability Evaluation... A stagnant cutoff low in the Gulf of Alaska to begin the period next Monday, should gradually shift east and weaken as a weaker low drifts south across the Aleutians into the North Pacific (or possibly eastward into the Gulf) and upper level ridging builds across mainland Alaska. By the middle of next week, models suggest more pronounced upper troughing should develop over the Aleutians and extending into the Aleutians. The latest guidance shows good agreement on this pattern for days 4-5, but thereafter the pattern becomes increasing uncertain. The 12z GFS is an outlier is dragging the initial weak upper low over the Aleutians into the Gulf, as well as later period rapid development of energy out of the base of the Bering Sea trough into a deeper low again over the Aleutians. The 00z/12z ECMWF runs are more consistent with the means which is noticeably weaker with late period energy over the Aleutians and the main core of the vortex remaining farther north over eastern Siberia. As such, WPC relied on a rapidly increasing blend towards the ECENS/GEFS by days 7-8 with smaller contributions from the ECMWF for added system definition. ...Weather/Threats Highlights... The main areas of precipitation and unsettled weather will be focused across the western the northwestern mainland throughout the period in the vicinity of a nearly stationary surface boundary draped across the region. Waves and precipitation may increase slightly mid week as stronger energy reaches the area, but still rainfall amounts don't appear to be too significant or hazardous at this time. Troughing extending into the Bering Sea and Aleutians later in the week could lead to some higher waves and more precipitation as well. Otherwise, generally below normal temperatures are expected across the mainland for much of the week, particularly in the far North, but values across the central part of the state should gradually trend warmer underneath of upper level ridging. Santorelli 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 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