Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 537 PM EST Tue Dec 13 2022 Valid 12Z Sat Dec 17 2022 - 12Z Wed Dec 21 2022 ...Interior to Panhandle cold wave with some record values possible... ...Guidance/Predictability Assessment and Preferences... The 12 UTC ECMWF/UKMET models seem best clustered for this weekend with GEFS/ECMWF ensemble set in between stronger main upper ridge solutions of the 12 UTC Canadian model and a more mainland shortwave undercutting solution now of the 12 UTC GFS. Prefer to transition to a blend of the GEFS/ECMWF ensemble means by next week amid growing model forecast spread and considering overall less than stellar run to run continuity of the models recently. This WPC/Alaska offices collaborated solution is only slightly on the more amplified side of a model composite. Established and amplified upper ridges historically tend to persist across medium range time scales well on the more amplified side of the full envelope of solutions, but this ridge only becomes established over the next few days and is more open to uncertainty for the time being. WPC product continuity is reasonable with the forecast plan. ...Pattern Overview and Weather/Hazards Highlights... A strong and shielding mid-upper level ridge axis is forecast to build northward across much of the western mainland and the eastern Bering Sea for the weekend as shortwave energies dig sharply to the lee of the ridge over a cold eastern mainland and Southeast Panhandle. Strong surface high pressure spilling from over the Interior and Yukon (in excess 1050mb, possibly higher in some models) will spread much below normal temperatures into the Southeast Panhandle. The ridge may lose some integrity into next week with guidance solutions varied with extent that the northern portion develops a closed high over the Chukchi Sea as uncertain upper shortwave energies divert/undercut over the Interior. The main Pacific low storm track and most precipitation is held to the south of much of the state in guidance through this forecast period regardless, but may still affect the Aleutians as a building upper trough nudging into the region/southwestern ridge periphery will likely support a few organized surface lows with moderate precipitation. The large scale flow around these lows could eventually also bring some modest lead precipitation downstream into the Alaskan Peninsula and southern coast. Schichtel Hazards: - Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, Sat-Tue, Dec 17-Dec 20. 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