Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 608 PM EST Tue Jan 07 2020 Valid 12Z Sat Jan 11 2020 - 12Z Wed Jan 15 2020 ...Guidance/Predictability Assessment... The latest runs of the 12z GFS/ECMWF show fairly good agreement on a deep low pressure system moving into the Bering Sea this weekend, weakening as it moves into northwest Alaska by Monday. Behind this, another shortwave will slide south of the Aleutians, showing potential strengthening as it moves into the Gulf of Alaska next Tuesday and Wednesday. The 12z GFS remains on the faster and deeper side of the solution envelope with this system, especially after day 6. The 00z ECMWF seemed totally out of line with much of guidance as it brought this system northward into the Bering Sea. The 12z ECMWF however came into better agreement with the GFS and ensemble means and is very much usable. The next possibly deep surface low moves into the far western Aleutians day 7/8 time frame with again, growing uncertainty amongst the latest deterministic runs. The WPC blend for today leaned heavily on the deterministic GFS and ECMWF for days 4 and 5 given the agreement, with increasing contributions from the ensemble means day 6 and beyond. The means tended to wash out the shortwave moving into the Gulf early next week so the blend used about a third of the 12z ECMWF through day 8 to bring back some definition of both the upper system and the resulting surface low. The blend for today fits well with yesterday's forecast as well as the forecast downstream over the CONUS. ...Weather/Hazards Highlights... A building upper ridge over the North Slope and much of the Interior will partially ease the current cold snap, with lingering much below normal air held over the eastern Interior/Southeast and Panhandle region as post-frontal high pressure spreads in from Canada. The main weather threat upstream will be from the Aleutians to the Bering Sea associated with a major low pressure system. This brings along with it the threat for some locally heavy precipitation, along with high winds and waves to mainly the western Aleutians. Precipitation should also work its way into the western and southwestern mainland this weekend. The shortwave moving into an already unsettled Gulf of Alaska early next week should bring more modest effects for maritime interests and onshore to the southern Alaskan tier. The next deep low for the Aleutians may bring a period of gusty winds and heavy precipitation by the middle of next week. Santorelli 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: - Much below normal temperatures across portions of mainland Alaska, Fri-Sun, Jan 10-Jan 12. - Much below normal temperatures across portions of the Alaska Panhandle, Fri-Mon, Jan 10-Jan 13. 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