Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 522 PM EST Fri Dec 23 2022 Valid 12Z Tue Dec 27 2022 - 12Z Sat Dec 31 2022 ...South-central Alaska heavy precipitation threat continues next week as Interior cold snap moderates... ...Guidance/Predictability Assessment and Preferences... Forecast spread has decreased significantly compared to yesterday with the 12 UTC GFS now more in line with the 12 UTC ECMWF/Canadian next week. A favored composite blend will hopefully maintain continuity in the coming days as guidance starts to converge on a more similar forecast evolution, reasonably bolstering forecast confidence. However, predictability drops off quickly into New Year's Eve weekend with the 12 UTC GEFS mean seemingly the best forecast continuation at this time to ring into 2023. WPC product continuity seems reasonable considering latest issues, but this solution with more prolonged and deeper northern Gulf of Alaska lead and subsequent low possibilities does suggest a Southcentral Alaska heavy precipitation threat pattern may remain for much of the rest of the this year. ...Overview and Weather/Hazards Highlights... The ongoing holiday cold wave with much below normal temperatures/deep surface high pressure centered across east-central portions of Alaska will moderate some next week along with values over the rest of the Interior/North Slope as a mean upper trough aloft slowly erodes. Meanwhile, an evolving/amplified upper level trough is expected to work from the southern Bering/Aleutians to the coast of Southwest Alaska next week. Several shortwaves will rotate around the low, being invigorated by a strong North Pacific jet. These shortwaves will intensify a series of North Pacific lows as they move south of the low and the Aleutians and into the Gulf. Pacific onshore flow and plentiful cloud cover with Pacific low/frontal system advents should meanwhile work to bring temperatures above normal by midweek across the Panhandle, and much closer to normal across Southcentral. There remains a threat for some precipitation into the Aleutians and through the AKpen, but heaviest amounts should focus downstream for the coast/interior Southcentral into early next week with an organized/deepened low lingering offshore, with protracted wrapping moisture working inland. There is also a growing guidance signal that the heavy precipitation threat across the Southcentral and vicinity may linger/renew later next week with additional low/frontal system development and approach. Schichtel Hazards: - Heavy precipitation across the northern Alaska Panhandle and Southcentral Alaska, Mon-Tue, Dec 26-Dec 27. - Much below normal temperatures across portions of eastern interior Alaska, Mon, Dec 26. 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