Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 524 PM EST Sat Nov 20 2021 Valid 12Z Wed Nov 24 2021 - 12Z Sun Nov 28 2021 ***Very cold over much of the Interior and heavy precipitation likely for southeast portions of the state*** ...Overview and Guidance Evaluation/Preferences... The 12Z deterministic guidance and ensemble means are in good agreement with a strong and cold upper low over the southern mainland through the end of next week, with multiple shortwave perturbations crossing south of the Aleutians and the Gulf region. By Friday and into next weekend, models differences are more apparent with the next storm system crossing south of the Aleutians, with the CMC farther south compared to the ensemble means. By the end of the forecast period, model differences are pronounced over the northern Pacific with respect to a potentially powerful low pressure system entering the Gulf, with the GFS considerably stronger and faster and the ECMWF a bit slower and a little weaker. The CMC is not favored given its depiction of a ridge axis over the same general vicinity. The WPC forecast was primarily based from a ECMWF/GFS/UKMET blend through Thursday, and then GFS/ECMWF and increasing use of the ensemble means through next weekend. ...Weather/Hazard Highlights... One of the main things that will make weather headlines will be the bitterly cold temperatures for this early in the season across much of the mainland as Old Man Winter makes an early arrival, with the greatest temperature anomalies of 10-20+ degrees below normal for western and southern portions of the Interior with subzero high temperatures likely for many areas, with mainly dry conditions expected. The other thing will be heavy snow and high winds for the coastal mountain ranges from the Kenai Peninsula to the southeast Panhandle, and heavy rain for areas near sea level, mainly for the second half of the work week. Periods of strong winds are also likely for much of the Aleutians with a tight pressure gradient in place owing to intense storm systems passing to the south. Hamrick 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