Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 612 PM EST Mon Mar 08 2021 Valid 12Z Fri Mar 12 2021 - 12Z Tue Mar 16 2021 ...Overview and Guidance/Uncertainty Assessment... Progressive quasi-zonal flow in the mid- and higher latitudes will trend toward increased troughing in the Bering Sea, downstream of elongated upper ridging from eastern Asia (China/Mongolia) into the western Pacific Ocean between 35-45N. Coupled with increasing ridging over the Canadian Archipelago, this may act to at least temporarily slow the pattern as a couple closed systems try to develop south of Alaska. Lead system out of the northeastern Pacific will still be subject to adjustments into the short range, owing to continued differences in timing/strength of northern and southern stream influences. Non-Canadian consensus was preferred as the Canadian remained most aggressive with a closed low likely too far north (~45N) compared to the ECMWF/GFS (~30N). Trailing shortwave may help linger at least part of the front near the southern Panhandle early Saturday. To the west, deepening troughing will favor increased meridional flow across the Aleutians and then into western areas of the Mainland as a robust southern stream low lifts into the Bering Sea late Fri into early Sat. Guidance has trended stronger with this low compared to the in-situ surface low over the NW Bering, but otherwise maintained the same idea as the past several days. Trended toward an even deterministic/ensemble blend between the GFS/ECMWF given enough agreement overall. System should break apart, stretched in the flow, with its southern portion moving into the Gulf and perhaps slowing as the pattern may amplify over the Northeastern Pacific into Northwestern Canada. ...Weather/Hazards Highlights... High pressure over the Interior Friday will drift eastward then southeastward this weekend, supporting colder temperatures 10-20 degrees below normal from Southcentral Fri to southeastern areas and the Panhandle by the weekend. Ahead of the Bering system, temperatures will rise to well above normal values along western coastal areas, perhaps 10-25 degrees (actual temperatures 10s/20s north, 30s over southwestern areas). After the system weakens and translates into the Gulf, cooler air will move back into western areas. Lingering rain/snow will exit the Panhandle Friday (timing differences to be resolved in the short range), focusing the precipitation mostly south of Juneau. Next system in the Bering will bring windy conditions and some rain/snow to the islands, enhanced around the incoming southern surface low. Milder temperatures suggest a transition from snow to rain for some areas. Another wave along the front is forecast to redevelop into the Gulf, perhaps enhancing the rain/snow over the AKPen/southwest/coastal Southcentral areas and Kodiak. Fracasso Hazards: - High winds possible for the western portions of the Aleutians, Sat, Mar 13. 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