Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 641 PM EDT Sun Jun 14 2020 Valid 12Z Thu Jun 18 2020 - 12Z Mon Jun 22 2020 ...Overview and Weather Highlights/Threats... For the forecast period /Thur-Mon/, a closed upper low settles over portions of the Aleutians and will be the driver for much of the synoptic pattern for the region through the period. A few waves of low pressure are forecast to develop along the southern periphery of this feature, generally tracking well south of the mainland over the North Pacific. Some periods of unsettled weather are possible given the upper low in place, but widespread hazardous precipitation is not expected. Across the mainland, the mostly ridging in place should result in slightly above average temperatures and mesoscale driven sensible weather characterized by showers and thunderstorms in the afternoon. ...Guidance/Predictability Assessment... A relatively persistent upper level pattern is expected through the medium range period characterized by an upper level low situated over portions of the Aleutians from day 4 (Thursday) to day 8 (Monday). Several waves of low pressure will ride the southern periphrey of this main feature in a relative fast progression, which is where forecast confidence drops below average. Timing and strength of individual features is difficult and run to run consistency is average at best. The 12Z CMC, while offering a decent and agreeable solution for d4, quickly drops out of favor with significant timing and strength issues compared to the more stable and reliable ECMWF/ECENS solutions. The 12Z GFS does show some agreement with the ECMWF through the period at times, particularly in the latter periods with another area of low pressure forecast to develop south of the Aleutians. Given the swings run to run seen in the last couple of days, a more conservative approach leaned on the ECMWF/ECENS was utilized with some inclusion of the GFS/GEFS for day 6-8. Taylor 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 Hazards: No significant hazards are expected over Alaska during this forecast period. 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