Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 634 PM EST Fri Mar 05 2021 Valid 12Z Tue Mar 09 2021 - 12Z Sat Mar 13 2021 ...Overview and Guidance/Uncertainty Assessment... An upper low over the East Siberian Sea will drift northward toward the Pole with quasi-zonal flow underneath it across the North Pacific/Aleutians. The flow has potential to become unstable, leading to wave-breaking and a closed low (or two) across the mid-latitudes, but should otherwise remain mostly west-to-east along 50N. Consensus has mostly stayed the course on timing and system track, with perhaps only a slightly slower progression overall though this could be mired in differing northern vs southern stream (high latitude vs mid-latitude) speeds. The 12Z GFS and ECMWF were comparable enough with the ensemble means though the GFS/GEFS were generally a bit quicker than the ECMWF and its ensembles. The parallel GFS was slower than the GFS and showed a lagging upper low to the south, so favored a slightly slower position than a straight consensus. This would affect the system headed toward the Panhandle later next week and how it evolves. ...Weather/Hazards Highlights... Light to perhaps modest rain/snow is expected with the first system across the Gulf Tue-Wed after it splits into at least two pieces (the first well north into the Arctic). High pressure will settle into the Interior and Southcentral Thu-Sat with colder temperatures 10-15 degrees below normal. Pacific system will bring in more organized rain/snow to the Panhandle later next week, though timing is uncertain as it will depend on system evolution. Next system in the Bering will bring windy conditions and some rain/snow to the islands as the parent low stays well northwest. Fracasso Hazards: - Heavy precipitation across portions of mainland Alaska, Mon, Mar 8. - Heavy snow across portions of mainland Alaska, Mon, Mar 8. - High winds across portions of mainland Alaska, Mon-Tue, Mar 8-Mar 9. - High winds across portions of the Aleutians, Thu-Fri, Mar 11-Mar 12. 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