Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 658 PM EST Thu Nov 17 2022 Valid 12Z Mon Nov 21 2022 - 12Z Fri Nov 25 2022 ...Overview... There will be strong ridging in place across much of the Mainland this weekend/early next week that will help deflect the main storm track to the south. During this period a series of low pressure systems are expected to track from near/south of the Aleutians/North Pacific into the Gulf of Alaska. These systems will usher in periods of gusty winds and modest to heavy precipitation to places along the Southern Coast and Southeast Alaska. The ridge is anticipated to weaken and shift eastward as an upper low over eastern Russia sends troughing into the Bering Sea and Western Alaska during to early to middle part of next week. ...Guidance/Predictability Assessment and Preferences... Overall the latest deterministic guidance and their ensemble means have an above average grasp on the evolution of multiple systems even tough there are typical timing and strength differences. The spread in the solution become more evident by Tuesday and increase thereafter as one upper low/surface low moves from just south of the Aleutians into the Gulf of Alaska. This initial low should eventually weaken in favor of a second low which deepens as it lifts from the North Pacific and again into the Gulf next Wednesday-Thursday. The feature will have increased uncertainty beyond Thursday will likely will hang out along the coast with additional minor timing of amplified troughing across the Bering and into western Alaska. Yesterday it was noted that the CMC solutions gets out of phase with the next system. However today it appears that the CMC is closer to the GFS, EC and GEFS means and the ECWMF is the model to begin to diverge, albeit with the same idea but much further north/northeast than the cluster. The WPC forecast used a blend of the CMC, GFS, and ECMWF with the ensemble means through the entire extended, however the weighing of the CMC/GFS were more than the ECWMF after day 5. Additionally the weighting of the means increased beyond day 5 as well. ...Sensible Weather and Potential Hazards... The initial surface low into the Gulf will continue to produce at least moderate, with some locally heavy, precipitation (coastal rain/mountain snows) this weekend from parts of the Southern Coast and the northern Panhandle. Activity should also linger into the early week but with more uncertainty on specific amounts. The second low into the Gulf should also bring additional unsettled weather to the region around the middle of next week. A cold front through western and central Alaska may also bring some precipitation in spots, but overall should be light and scattered in nature. In addition, strong gap winds could develop by Tuesday or Wednesday across some southern locations. The upper ridge lingering this weekend will continue to support above normal temperatures for much the state, with the greatest anomalies across the North Slope. While the North Slope (and parts of far eastern Alaska) should stay above normal even into next week, the rest of the state will experience a significant cooling trend as a strong cold front moves through. Anomalies across western and southwest Alaska could be 10 to 20 degrees below normal by next Thursday. Campbell/Santorelli Hazards: - Heavy precipitation across portions of the southern coastal Alaska, Sun, Nov 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