Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 613 PM EST Sat Jan 18 2020 Valid 12Z Wed Jan 22 2020 - 12Z Sun Jan 26 2020 A mean trough/upper low is forecast to develop/persist across the Arctic Ocean north of Alaska and Siberia through the the middle of next week, with an active storm track across the North Pacific, generally south of the Aleutians, and into the Gulf of Alaska. Models/ensemble today have solidified a trend toward developing a negatively tilted upper ridge axis from the Gulf of Alaska across the Alaska Peninsula and into the eastern Bering Sea by late next week. If this occurs, it would allow for the potential for shortwave energy originating in the arctic to amplify and dive southeastward around the eastern side of the ridge, potentially affecting eastern portions of Alaska with colder temperatures. The ridge also appears to be wreaking some degree of havoc with respect to the evolution of low pressure systems in the aforementioned North Pacific storm track, with spread quickly increasing by the latter part of the forecast period. A blend of the ECMWF/GFS served as a forecast starting point early in the period, with a low pressure system forecast to track into the southern Gulf of Alaska, spreading widespread precipitation into the Alaska Panhandle. Following low pressure systems in the series show greater spread, with some consensus that another system should track south of the Aleutians Thu-Fri and into the Gulf on Sat, and perhaps another passing south of the Aleutians Sat night into Sun (although confidence is quite low by that point in time). Given the increased spread, began quickly boosting components of ECENS/GEFS ensemble means in the forecast starting on day 5 (Thu) through the remainder of the forecast period. 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 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