Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 530 PM EST Fri Jan 21 2022 Valid 12Z Tue Jan 25 2022 - 12Z Sat Jan 29 2022 ...Overview... The upper ridge axis that will be in place across much of mainland Alaska for this weekend and early next week will be shunted eastward as a cold upper trough moves in from the Bering, and results in much colder weather spreading from west to east through the middle to end of the week. Meanwhile, a storm system over the Gulf will lift northeastward towards the southeast Panhandle region and result in unsettled weather near the coast for the end of the week, and another surface low near the Aleutians will also tend to keep rain/snow across the islands through the middle to end of the week. ...Guidance/Uncertainty Assessment... The 12Z model guidance suite has decent overall agreement on the large scale pattern Tuesday, with the exception for the northern Gulf region where the GFS is much stronger with a lead surface low/trough. However, the GFS is more in line with the next and larger storm system entering the Gulf region late Wednesday into Thursday, and then diverges again from the consensus by Friday by lingering the upper low over the Gulf much longer and loses ensemble support. For the potentially major Aleutian low, the GFS and UKMET are quite intense with the surface low, and the GFS appears too progressive in lifting this low north across the western Bering, whereas the CMC is more suppressed and a little weaker. Therefore a UKMET/ECMWF/CMC is the primarily blend through Thursday owing to the differences noted with the 12Z GFS. By the end of the forecast period next Saturday, model spread is significant and the ensemble means offer the best starting point in the forecast process by this time. ...Weather/Hazard Highlights... The pattern change that is forecast to take place across much of the state will tend to result in less snow showers across the mainland as arctic high pressure builds into the region. The exceptions will be across the southern coastal region and the southeast panhandle where moist onshore flow ahead of the Gulf low will likely produce widespread precipitation starting on Wednesday, with very heavy snow for the coastal mountain ranges and strong winds near the coast. Periods of rain/snow are also likely through middle to end of the week for the central and western Aleutians. Widespread much above normal temperatures will likely continue until Tuesday underneath the departing upper-level ridge, with temperatures running about 15-30F above average for the eastern half of the mainland. The passage of the strong cold front will cause temperatures to fall to below normal levels from west to east through mid-week across most of the state as the ridge moves away from the state and the arctic trough builds back in. Hamrick Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 24. - High winds across portions of the Alaska Panhandle and mainland Alaska, Mon, Jan 24. 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