Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 605 PM EST Sun Jan 31 2021 Valid 12Z Thu Feb 04 2021 - 12Z Mon Feb 08 2021 ...Overview and Guidance/Uncertainty Assessment... A rather changeable upper pattern will be loosely driven by troughing in the Bering Sea and ridging over the northeastern Pacific that will, at times, poke into the mainland. The models and even ensembles have shifted early in the period (Tue-Wed) with the flow off Asia as well as to the south of the Aleutians. This had a downstream affect to increase the southerly extent of troughing south of 50N around Fri as well as a more northerly extent of mid-latitude energy along 160W (previously forecast to stay south of 50N). Net result is a more developed/phased system lifting out of the mid-latitudes Fri into the eastern Aleutians and perhaps Bristol Bay (GEFS/CMCE consensus) or just east of the AKPen (ECMWF/ECMWF ensembles). This could then be enough to erode the upper ridge enough over the Gulf to allow lower heights to invade from the northeast (NW Canada) next weekend into Mon 8 Feb. GFS/GEFS were most aggressive with this scenario while the Canadian/ECMWF and their ensembles were farther northeast over Banks Island or the Beaufort Sea. Finally, flow over the western Pacific into the Bering and/or Aleutians remains quite uncertain with little predictability. Thus, weighed heavily on the ensemble means after a general deterministic blend Thu. This included majority ECMWF/Canadian ensembles and minority GEFS ensembles. ...Weather/Hazards Highlights... Precipitation will focus around the central to eastern Aleutians as the low pressure lifts northward Friday, spreading light to modest snow and some coastal rain to southwestern areas of the mainland eastward across coastal Southcentral and into the Panhandle late Fri into Sat. Warm front may bring enhanced rain/snow to southeastern areas per the guidance, but this varies in space and time. Ensembles focus around Yakutat but encompass anywhere from PWC to the southern Panhandle. Another system may spread more rain/snow to the Aleutians next weekend and into the Gulf next Monday. Temperatures will be near to above normal over the southwestern half of the state and near to below normal over the northern/northeastern portions as well as over the Panhandle. Fracasso 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