Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 639 PM EST Mon Jan 23 2023 Valid 12Z Fri Jan 27 2023 - 12Z Tue Jan 31 2023 ...Significant pattern change will lead to increased chances of precipitation, milder than normal temperatures, and potential for gusty winds from the Aleutians to the western mainland late this week to early next week... ...Overview... As the medium range period begins Friday, a pattern change will be underway as mean upper ridging builds in atop the state lasting into next week, in response to a couple of large upper troughs/lows in the western Bering Sea. Above average temperatures will abound over the mainland given the ridge. The Aleutians and Alaska Peninsula and into the western mainland are likely to see more active weather with precipitation and gusty winds. Meanwhile the Panhandle should see a drying trend as well as cooling temperatures and some outflow winds with northerly flow to the east of the ridge axis. ...Model Guidance/Predictability Assessment... While model guidance has stayed reasonably well clustered with the overall Bering Sea trough/mainland ridge pattern, notable differences in the details remain. Late this week, there is already model spread for the interface of the trough/ridge and thus the western side of the ridge's orientation, particularly affecting western Alaska with how much QPF, wind, etc. impacts there will be. Namely, recent GFS runs show shortwave energy making its way farther east into southwestern Alaska by late Friday/Saturday than other guidance that maintains the ridging across that region. Ensemble means are generally in between, with north-south oriented heights there on the western side of the ridge, possibly partly because a middle ground solution is most likely but also because ensemble members show spread in their orientation. Comparing to the 12Z suite of ensemble members for the EC, GEFS, and CMC ensembles does show that the 12Z GFS with its shortwave over southwest Alaska seems like an outlier, and also the GFS seems to have a less likely solution for the orientation of the ridge bending northwestward a bit. Favoring the ensemble means and more of a lean toward the ECMWF/CMC solutions seems prudent for now. By Sunday there is some signal in that cluster for a shortwave to pass through northwestern AK and rounding through the northern tier. Then models/ensembles tend to indicate ridging rebuilding Monday/Tuesday downstream from more Bering Sea troughing/large surface lows, though the GFS runs are more wonky. The WPC forecast favored leaning toward the ensemble means for the latter part of the period that were in the best agreement. ...Sensible Weather and Potential Hazards... Ridging becoming established into the mainland should help moderate temperatures to well above normal across much of the state, with possible +30F anomalies for parts of the northwestern mainland by early next week. Temperatures could warm above the freezing mark in the southwestern mainland/Bristol Bay area, quite a change from current conditions. There could be impacts from snowmelt with these above freezing temperatures, and especially if precipitation falls as rain or freezing rain there due to the relative warmth. This is a possibility late week as precipitation crosses the Aleutians/Alaska Peninsula as well as some possibly gusty winds along a front stemming from the western Bering low, which potentially makes its way into the western mainland, though the impacts farther east are less certain. The pattern seems to repeat itself for early next week for another round of possible western Alaska precipitation/winds. Some available moisture could lead to snow showers over much of the mainland through next weekend, but currently only light QPF is expected. The Panhandle on the other hand is likely to see drier conditions than they have lately, as well as temperatures becoming slightly below average, and winds perhaps becoming gusty with offshore flow. Tate 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 Hazards: - Heavy precipitation across portions of mainland Alaska and the Aleutians, Thu-Fri, Jan 26-Jan 27. - Much above normal temperatures across portions of mainland Alaska, Fri-Sun, Jan 27-Jan 29. 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