Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 719 PM EDT Tue Jun 15 2021 Valid 12Z Sat Jun 19 2021 - 12Z Wed Jun 23 2021 ...Guidance/Predictability Evaluation... The WPC Alaskan medium range product suite was primarily derived from a composite blend of well clustered guidance of the 12 UTC GFS/ECMWF, and the 12 UTC GEFS/CMC/ECMWF/NAEFS ensemble means Day 4-8 (Saturday-next Wednesday). Guidance forecast spread continues to indicate above normal predictability. A general model compromise starting from Day 4 followed by increasing use of the ensemble means for Days 6-8 should provide a good starting point. This will allow a mid-latitude cyclone to track near the Aleutians at a similar speed and intensity as continuity for early to middle of next week. ...Weather/Threats Highlights... A lead system that tracks from south of the Alaskan Peninsula toward the Gulf of Alaska this weekend is expected to produce unsettled maritime conditions along with a periodic rain focus into the Alaskan Peninsula and southern to southeast Alaska. Meanwhile, a warming mean upper ridge is expected to linger over much of the Interior and North Slope into the weekend, but embedded small scale impulses may support spotty local activity. The upper ridge transitions from the weekend into early next week as the pattern modifies to allow potentially vigorous ocean storms lifting toward the Aleutians, the Alaska Peninsula, and Southwest/southern Alaska. This is slated to occur as ample upper trough/system energies approach from eastern Asia and the Pacific mid-latitudes to interact with lingering northern stream energies and entrain deeper moisture. This offers an emerging maritime and regional threat to monitor as an occluded cyclone will most likely impact areas from the Aleutians to the Alaskan Peninsula in much wetter pattern toward the middle of next week. Kong/Schichtel 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