Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 651 PM EST Tue Feb 23 2021 Valid 12Z Sat Feb 27 2021 - 12Z Wed Mar 03 2021 ...Active Pattern from the Bering Sea/Aleutians to the Mainland/Gulf of Alaska... ...Overview and Guidance/Uncertainty Assessment... Upper pattern will be driven by a strong positive height anomaly moving off Hokkaido this weekend (+3.5 sigma 500mb heights per the ECMWF ensemble mean) will eventually translate eastward to the western Bering Sea by the middle of next week. This will favor downstream robust yet progressive troughing through the Bering to the Gulf of Alaska in general west-to-east flow. With a rather defined wavelength, the models/ensembles were in good agreement overall except for the UKMET. There were timing differences between the GEFS/ECMWF ensembles but a middle ground solution was preferred absent any notable trends. This fit close to continuity as well. Increased ensemble weighting by later in the period due to uncertainty in smaller-scale features that may or may not deepen (or even exist) within the flow. ...Weather/Hazards Highlights... Mild temperatures late this week over southwestern areas will be replaced by cooler than normal temperatures after the lead front pushes through and heads swiftly through the Gulf/Panhandle Saturday into early Sunday. GFS was much wetter than the ECMWF (Canadian near the middle) but a blended solution should suffice as the progressive pattern should limit excessive precipitation totals, but amounts could top a couple inches (liquid) with this system. Next system will bring another round of wind to the Aleutians/Bering into southwestern areas late Sun through Mon then into the Gulf around next Tue. The ECMWF was much wetter than the GFS with that system but the Canadian was near the middle. Again, system should be progressive to limit excessive amounts but still 1-3" (liquid) may be possible from Southeastern areas into the Panhandle. Temperatures will trend toward normal and then below normal over much of the state by the middle of next week as the upper low moves through. Fracasso Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat-Sun, Feb 27-Feb 28. - High winds across portions of mainland Alaska and the Aleutians, Mon-Tue, Mar 1-Mar 2. - High winds across portions of the Aleutians, Sun-Tue, Feb 28-Mar 2. - Much above normal temperatures across portions of mainland Alaska, Fri-Sat, Feb 26-Feb 27. 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