Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 434 PM EST Tue Dec 01 2020 Valid 12Z Sat Dec 05 2020 - 12Z Wed Dec 09 2020 ...Significant Gulf of Alaska storms offer a weekend to early next week heavy precipitation and high wind threat for southern to southeast Alaska.... ...Guidance and Uncertainty Assessment... Forecast spread remains less then stellar, so system timing and placement details remain more suspect than usual through medium range time scales. Accordingly, the WPC Alaskan medium range product suite was primarily derived from the mainly compatible 12 UTC GEFS/ECMWF ensemble means and the 19 UTC National Blend of Models. The overall larger scale pattern evolution in guidance offers better predictability, so manually adjusted offshore surface low systems deeper as consistent with favorable support aloft and deepening model system trends. This solution was collaborated with local Alaskan offices and maintains good WPC continuity. ...Weather/Hazards Highlights... Expect an overall more benign weather pattern to settle into much of the North Slope and the Interior heading this weekend. Underneath, a lead Pacific system lifting up through the eastern Gulf of Alaska Saturday offers less than ideal model forecast spread, but does show potential to focus heavy precipitation and high winds from a stormy Gulf into southern/southeast Alaska. A subsequent and much deeper/larger low with amplified upper trough/low support has a growing guidance threat signal for major maritime disruption and heavy precipitation/high winds across the Gulf and onshore back into southern and southeast Alaska later weekend into early next week. Additional low energies upstream with more uncertain development potential are then slated to work from the Pacific toward the Aleutians and the Gulf early-mid next week in continued unsettled flow. Schichtel Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sat-Mon, Dec 5-Dec 7. - Heavy precipitation across portions of the Alaska Panhandle, Fri-Mon, Dec 4-Dec 7. - High winds across portions of the Alaska Panhandle and mainland Alaska, Sat-Sun, Dec 5-Dec 6. 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