Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 659 PM EST Thu Jan 19 2023 Valid 12Z Mon Jan 23 2023 - 12Z Fri Jan 27 2023 ...Prolonged threat of heavy precipitation expected along the southern coast to the Panhandle for much of next week... ...Synoptic Overview, Sensible Weather as well as Model Guidance Assessment... The medium-range forecast period will begin on Monday with an occluded cyclone forecast to push northward across the Aleutians, setting the stage for the arrival of another heavy precipitation event from the southern coast to the Panhandle. Model guidance today, especially the ECMWF and the EC mean, has decidedly shifted the cyclone track farther north, bringing the center of the cyclone earlier across the Aleutians and into the southern portion of the Bering Sea by Monday. This is in response to a significant northward shift of a blocking upper-level high across northeastern Siberia as well as a cold low north of Alaska. This northward shift in the guidance results in a westward shift in the threat of heavy precipitation into the eastern portion of the Alaska Peninsula on Monday. Thereafter, models agree that the main energy of the system will be sheared off to the east, allowing the cyclone to weaken in place near the Aleutians, while developing a deep and sustained stream of Pacific moisture toward the southern coast and the Panhandle. This will keep the southern coastline and the Panhandle under a prolonged threat of heavy precipitation for the remainder of next week, especially when low pressure waves form just off the coast. In addition to the influx of moisture, the onshore flow will likely keep temperatures relatively mild by January standards across southern Alaska, especially near the coast. The coldest weather is expected to be north of the Brooks Range where subzero high temperatures are likely most days. Some residual moisture from the southern coast should make it northward into interior Alaska and precipitate as light snow through much of next week. By next Friday, ensemble means show good agreement that an upper-level ridge of high pressure will be building into the Gulf and extending into Alaska. This could be the beginning of a drying trend following an extended period of heavy precipitation across the southern coast and the Panhandle. Meanwhile, the next occluded cyclone is forecast to advance into the western portion of the Aleutians, accompanied with slight potential of heavy precipitation and high winds. The WPC medium-range forecasts were composed based on a 40% blend of the 12Z ECMWF/00Z EC mean, 40% 12Z GFS/GEFS, and 20% 12Z CMC/CMC mean, transitioning to mainly a blend of the corresponding ensemble means by Day 8. Kong Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Sun-Thu, Jan 22-Jan 26. - Heavy precipitation across portions of mainland Alaska, Sun, Jan 22. 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