Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 633 PM EDT Tue Jul 14 2020 Valid 12Z Sat Jul 18 2020 - 12Z Wed Jul 22 2020 ...Overview and Weather/Hazard Highlights... The flow pattern across the North Pacific is forecast to become gradually more amplified over the weekend and into early next week, with an upper trough strengthening from the Bering Sea south across the Aleutians, and an eastern Pacific ridge attempting to make some headway northward into the Gulf of Alaska. The amplifying flow will allow for increasing potential for arctic upper-level energy to move southward, with an arctic upper low expected to affect the North Slope and portions of the Interior this weekend, and another upper low forecast to dig south into the western Bering Sea Sun through early next week. The primary impact of the system affecting the North Slope will be on temperatures, with colder temperatures spreading across the region, and highs forecast to be 10-20 deg below average. Through time, cooler temperatures are forecast to spread farther south across much of mainland Alaska by by early next week. In the meantime, a low pressure/frontal system is forecast to move east across the Gulf of Alaska Sat as it weakens, with another similar system following a similar track next Mon-Tue. These systems, and persistent broad and unsettled onshore flow on the northern periphery of the upper ridge will keep wet conditions in place through much of the extended forecast period from the Alaska Peninsula to mainland Alaska as well as Southeast Alaska. ...Guidance/Predictability Assessment... Model/ensemble consensus has continued to show some improvement over recent days. The 12Z ECMWF seemed to be the deterministic solution most well-centered within the overall consensus through much of the extended forecast period. Thus, the ECMWF heavily weighted in the WPC forecast during days 4-5 (Sat-Sun). After that, a gradual trend toward heavier weight on ensemble means (ECENS/NAEFS) was shown through time, with ensembles comprising a majority of the forecast by days 7-8 (Tue-Wed). Ensemble consensus in terms of the large scale flow pattern across Alaska and the North Pacific was relatively good through day 8, with little in the way of significant pattern changes indicated. Thus, forecast confidence was average to slightly above average. Ryan 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