Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 532 PM EST Wed Dec 09 2020 Valid 12Z Sun Dec 13 2020 - 12Z Thu Dec 17 2020 ...Guidance and Uncertainty Assessment... Blocky high latitude features will eventually shake loose later next week in a pattern with relatively lower predictability than normal. Stable upper high near Wrangel Island will slowly move northward toward the Pole as the upper lows pinwheeling around the eastern Aleutians move east (eastern low) or weaken (northern low initially over the Interior). This should allow the pattern to unwind into a more progressive flow later next week. The models/ensembles generally agree on the evolution/breakdown but show much less agreement on system progression/track/depth. The 12Z ECMWF was preferred most overall along with much of the 12Z Canadian/UKMET as the GFS, though acceptable to start the forecast period, once again failed to deepen a system across the central Pacific that will likely lift into the southern Gulf around next Tue (per the ECMWF/Canadian/UKMET and most ensembles). Utilized no less than 40% weighting of the ensemble means to minimize daily changes in the forecast, increasing to about 90% by next Thu amid timing uncertainty in the increasingly zonal pattern. ...Weather/Hazards Highlights... Strong high pressure to the north and storminess in the Gulf will lead to windy conditions over the Interior from the east early next week, though rather dry. Systems in the Gulf or nearby areas will focus precipitation over coastal areas of the AKPen and Kenai peninsula on southeasterly flow. Parts of the Panhandle may see at least modest precipitation (especially the southern portions), though the proximity of the systems to the land areas remains in question. As a result, models solutions vary on intensity there with the GFS most wet. Temperatures will be near to above normal over northern areas of the mainland, but trending colder with time as upper heights lower. Near to below normal temperatures are expected over southwestern areas (under the cold upper low) and much of the Panhandle/eastern Interior with offshore flow at the surface. Fracasso Hazards: - High winds across the central portions of mainland Alaska, Sat-Wed, Dec 12-Dec 16. 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