Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 443 PM EST Sat Dec 24 2022 Valid 12Z Wed Dec 28 2022 - 12Z Sun Jan 01 2023 ...Guidance/Predictability Assessment and Preferences... Forecast spread has increased yet again in guidance, mainly with upper trough/offshore system interactions. Uncertainty builds steadily through medium range time scales with embedded systems despite a reasonably similar larger scale pattern evolution. 12 UTC GFS/ECMWF solutions still seem reasonably well clustered with ensembles Wednesday into Thursday, but with less than stellar run-run continuity over time. Inclusion of some ensemble mean guidance with these models tends to smooth the less predictable detail in this time frame. Prefer to then quickly switch to a composite blend of the still reasonably compatible 12 UTC GEFS/ECMWF ensemble means for the rest of next week into the upcoming New Year. ...Overview and Weather/Hazards Highlights... It remains the case that the ongoing cold wave with much below normal temperatures/deep surface high pressure centered across east-central portions of Alaska will moderate next week along with values over the rest of the Interior/North Slope as a mean upper trough aloft slowly erodes with ridge/heights building. Meanwhile, an evolving/amplified upper level mean trough is expected to very slowly work from the vicinity of the Aleutians to off the coast of Southwest Alaska/the western Gulf of Alaska next week. Several significant 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 of Alaska. Accordingly, there will be renewed threats for enhanced precipitation out from the Aleutians to especially the AKpen/Kodiak Island and into Southcentral and also eventually downstream into Southeast Alaska with deepened lows offshore with deepened low/frontal system development. However, there is much uncertainty with the details of system interactions and developments, albeit in an overall favorable pattern to monitor. Schichtel 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