Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 623 PM EST Fri Jan 17 2025 Valid 12Z Tue Jan 21 2025 - 12Z Sat Jan 25 2025 ...Midweek storm expected to bring heavy precipitation across Kenai Peninsula and eastern portion of the Alaska Peninsula along with mountain snow across interior southwestern Alaska... ...General Overview with Model Guidance Assessment... The upper-level pattern over the Alaskan domain will continue to favor back-to-back cyclones to track across the Alaskan southern tier during much of the medium-range period ahead of an upper-level ridge that tends to re-establish itself over mainland Alaska from time to time. Models show good agreement that impacts associated with three significant cyclones will be felt across the Alaskan domain during the medium-range period. Heavy precipitation associated with the first cyclone is expected to relent as the system tracks northward into the Arctic Ocean away from Alaska beginning on Monday. The second system is forecast to track right along the Aleutian island chain early next week. Deterministic solutions showed a similar kind of divergence since yesterday as the cyclone center approaches the Alaska Peninsula by next Wednesday, with the GFS/GEFS solutions showing a noticeably slower forward motion than the ECMWF/EC mean solutions while the CMC/CMC mean solutions are slightly faster. The middle ground solutions from the ECMWF/EC mean are preferred. This general model preference is maintained through the rest of the medium-range period as the ensemble means show decent agreement for the next cyclone to track into the vicinity of western Bering Sea by the latter part of next week. By late next week going into the weekend, ensemble means indicate a general consensus for a ridge to strengthen and extend northward through mainland Alaska, which would effectively block the eastward progress of the third cyclone moving into the vicinity of the western Bering Sea. The WPC medium-range package was based on 40% from the 12Z ECMWF and 00Z/12Z EC mean, 40% from the 12Z GFS and 12Z GEFS, and 20% from the 12Z CMC and 12Z CMC mean. This blend maintains reasonably good WPC product continuity. ...Weather/Hazards Highlights... As heavy precipitation impacts associated with a departing cyclone relent across western and southern sections of mainland Alaska early next week, the second in a series of cyclones will be tracking through the Aleutians. This system will likely bring strengthening winds and heavy precipitation across the Kenai Peninsula and eastern portion of the Alaska Peninsula on Tuesday. If the cyclone interacts with a stationary front draping across southwestern Alaska, a swath of moderate to heavy snow overrunning the front could impact the mountain ranges across interior southwestern Alaska Tuesday into early Wednesday. This scenario is indicated by most of the guidance except the GFS, though there is a fair amount of uncertainty regarding the placement of the heaviest snowfall axis. For the southern coastline to the Panhandle, only moderate amounts of precipitation are expected through midweek next week as the second cyclone is forecast to weaken over the Gulf of Alaska. The third cyclone should begin to make its presence known from west to east across the Aleutians later next week under strengthening southerly flow. There is decent ensemble mean agreement for the precipitation to reach western Alaska probably in the form of snow showers by Friday and going into next weekend but the details are unclear at this time. Meanwhile, above freezing high temperatures are forecast as far north as portions of northwestern Alaska on Monday as the first cyclone center tracks away further northward into the Arctic Ocean. Slightly colder air will move in thereafter but temperatures will remain well above normal for much of Alaska other than the southern portion of the Panhandle through the medium-range period. Kong 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