Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 648 PM EDT Sat Jun 13 2020 Valid 12Z Wed Jun 17 2020 - 12Z Sun Jun 21 2020 ...Overview and Weather Highlights/Threats... For the forecast period /Wed-Sun/, the main feature will be the developing area of low pressure and associated closed upper low that stalls/slows over portions of the North Pacific, south of the mainland. An area of low pressure is expected to track from south of the Aleutians to the North Pacific by mid-week then slow/stall with a large upper low setting up in the region. This will be competed by an area of upper ridging over the eastern mainland and northwest Canada that does begin to lift northward as the aforementioned system over the North Pacific. Some periods of wet weather could be possible early in the week with the aforementioned low 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... Forecast confidence remains average to slightly above average through the period, with the main focus being the developing mid/upper level low expected over portions of the Aleutians and North Pacific through the period. Areas of low pressure moving through the flow are more unpredictable with wider variance seen in the forecast guidance, but overall confidence is average even through day 8. The GFS/CMC/ECMWF all show agreement at 500 mb with the upper low mid to late week and generally upper ridging over the mainland beginning to lift northward as the aforementioned upper trough moves in. Typical model biases were seen with the GFS being too progressive while the CMC was a bit too amplified with the secondary area of low pressure developing. For the WPC blend, a near equal blend of the ECMWF/GFS/CMC was used for day 4 but quickly transitioned to a ECMWF heavy blend for day 5/6 followed by increasing weights of the ECENS/GEFS. 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