Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 411 PM EST Thu Dec 15 2022 Valid 12Z Mon Dec 19 2022 - 12Z Fri Dec 23 2022 ...Interior to Panhandle cold wave to threaten record temperatures... ...Guidance/Predictability Assessment and Preferences... Forecast spread has increased over medium range time scales, but especially from Tuesday onward with uncertain mainland upper trough energies cutting underneath a Chukchi Sea centered closed high/upper ridge. It seems that a composite blend of best clustered guidance from the 12 UTC GFS/ECMWF and GEFS/ECMWF ensemble means provides a good forecast basis for Monday. Beyond then, prefer to then quickly switch to thankfully still compatible and generally consistent GEFS/ECMWF ensemble means to maintain max WPC product continuty deeper into the holiday season, albeit with decreasing predictability and detail. ...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 frigid eastern mainland and eastern Gulf of Alaska/Southeast Panhandle. Strong surface high pressure spilling from over the Interior and Yukon (center upwards of 1060mb) will maintain much below normal to local record temperatures across the region and into the Southeast Panhandle well into next week. Minimum temperatures are expected to fall into the -40 to -50 F range in the colder spots of the eastern/southeastern Interior and colder than -10 F in favored spots of the Southeast Panhandle. This pattern also seems favorable for periods of enhanced gap winds to be monitored as they may approach high wind threat criteria in favored spots across the region. The main upper ridge may lose some integrity next week with recent guidance solutions less varied now with extent that the northern portion develops a closed high over the Chukchi Sea, but still less certain with upper shortwave energies that divert/undercut over the potentially unsettled Interior. Latest solutions have been trending toward some upwards to ample upper trough undercutting energy focus into the Interior and south-central Alaska. This could also allow modest northern Gulf of Alaska surface frontal low with overall broad cyclconic flow to support eventual light-moderate coastal precipitation across the Alaskan southern and southeast tier. In this pattern, the main Pacific low storm track and most precipitation remains held to the south of the state in guidance through this forecast period, but wrapping flow around these lows will affect the Aleutians/AKpen eastward as a building upper trough nudging into the region/southwestern upper ridge periphery likely supports windy/deepened maritime surface lows with additional onshore precipitation potential into later next week. Schichtel Hazards: - Much below normal temperatures across portions of the Alaska Panhandle and mainland Alaska, Sat-Tue, Dec 18-Dec 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