Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 519 PM EST Fri Dec 9 2022 Valid 12Z Tue Dec 13 2022 - 12Z Sat Dec 17 2022 ...Synoptic Overview... The overall weather pattern across the Alaska domain is expected to remain rather active for the beginning of next week with a Gulf low bringing heavy precipitation for southern coastal areas. This low weakens by midweek but is followed by a potentially stronger low pressure system developing over the Aleutians by the Wednesday-Thursday time period. A third system may enter the Bering Sea region by next weekend, but future forecasts will refine this potential further. Meanwhile, an upper level ridge will likely build in across eastern Alaska and northwestern Canada for Wednesday and beyond, with some potential for an omega block pattern trying to develop by next Saturday. ...Guidance/Predictability Assessment and Preferences... The 12Z model guidance suite is indicating a slightly higher level of uncertainty compared to what is typically seen in a Day 4 forecast. In this case, the past few runs of the CMC have appeared to differ the most from the consensus, particularly across the North Pacific, through the middle of next week. There is a decent model signal for a significant storm system emerging from eastern Siberia late next week, although big timing and latitudinal differences are apparent. The fronts/pressures forecast was primarily derived from a nearly equal blend of the GFS/ECMWF and their ensemble means, along with some of previous WPC continuity, and slightly increasing the proportion of the EC/GEFS means with each successive day. ...Weather/Hazards Highlights... This pattern should lead to increasingly milder conditions across much of the Interior as Pacific moisture advects northward across the state. The southwestern portion of the mainland should have the greatest expanse of above normal temperatures as onshore flow persists for much of the forecast period. Low pressure systems traversing the Bering Sea and North Pacific should bring gale to storm force winds to the Aleutians at times, with an initial system over the northern Gulf of Alaska likely bringing gales to the south-central and southeast coasts early next week. Therefore, the southern coastal areas are likely to have heavy snowfall for the coastal mountain ranges and periods of heavy rain near the coast. Hamrick Hazards: - Heavy precipitation across portions of the Alaska Panhandle and southern mainland Alaska, Mon, Dec 12. - Heavy precipitation across portions of southern mainland Alaska and the Aleutians, Tue-Wed, Dec 13-Dec 14. - High winds across portions of the Aleutians, Wed-Thu, Dec 14-Dec 15. Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook 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