Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 517 PM EST Fri Dec 02 2022 Valid 12Z Tue Dec 06 2022 - 12Z Sat Dec 10 2022 ...Guidance/Predictability Assessment and Preferences... The guidance shows general agreement concerning the general flow pattern in and around AK -- a persistent upper low/trough over Asia, broad ridging across the north-central Pacific and at times AK, and downstream troughing across the far northeast Pacific and western North America. The area of better model agreement was in and near the AK Panhandle. The same is not true in the Aleutians, where the guidance continues to struggle with the depth aloft of a shortwave/possible upper low and its related cyclone moving through/near the area, possibly into the Bering Sea. Currently, the 12z ECMWF is the most depressed/weakest aloft while the 12z UKMET is strongest/most closed aloft. In general, a more open system moving over the top of the broad central Pacific ridge makes the most sense, which would leave the UKMET as too strong/wrapped up. To deal with the uncertainty, for the 500 hPa heights, pressures, fronts, and winds, generally used a deterministic heavy blend of the 12z GFS, 12z ECMWF, 12z UKMET, and 12z Canadian early on before including up to 50% of the 12z NAEFS mean/00z ECMWF ensemble means thereafter with tweaks made (lower pressures and increase winds) so that systems weren't so washed out. This idea maintained reasonable continuity with Thursday's forecast. The QPF used the 19z NBM and, 12z GFS, 12z Canadian, and 12z ECMWF solutions. The remainder of the grids were 19z NBM weighted, as usual. ...Weather/Hazards Highlights... In Alaska, a strong pressure gradient over the mainland and Aleutians associated with back-to-back low pressure systems moving across the Arctic and eastern Russia will begin to relax Monday as the systems weaken and move further away from the region. Strong, gusty winds along the northern and western coasts should be subsiding by Monday morning. However, the threat for gusts over 60 mph will likely linger a bit longer across the western Aleutians through the day. Anomalously mild temperatures 20 to 30 degrees above normal over the mainland will keep temperatures near freezing along the western coast Monday while warmer air remains aloft. Freezing rain will continue through the day before transitioning to snow on Tuesday as temperatures finally cool a bit closer to normal. Heavy snow will still be possible for the higher elevations of the Brooks Range. Frontal systems moving along the southern coast will lead to snowfall in south-central AK but forecast amounts look to remain typical for early winter in the region. A stronger push of moist, onshore flow ahead of a developing low over the Gulf of Alaska on Wednesday will likely bring much heavier precipitation in the form of coastal rain and mountain snow to the southeast coast and Panhandle through Thursday. An interior cooling trend begins next Thursday night initially due to an upper level trough, but continues afterward due to convergence aloft between the departing upper trough and a developing upper ridge across western mainland AK leading to an increasingly cold and dry surface high pressure system enveloping the AK interior -- minimal cooling is expected within the North Slope. Lows in the Single digits and teens Wednesday night descend below zero/-10s out east Thursday night with pockets of -20s possible next Friday night. Roth/Russell/Putnam Hazards: - Heavy precipitation across portions of the Alaska Panhandle and mainland Alaska, Wed-Thu, Dec 7-Dec 8. - Heavy snow across portions of mainland Alaska, Mon, Dec 5. - Freezing rain across portions of mainland Alaska, Mon, Dec 5. - High winds across portions of the Aleutians, Mon, Dec 5. 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