Alaska Extended Forecast Discussion National Weather Service College Park MD 656 PM EDT Wed Sep 3 2025 Valid 12Z Sun 07 Sep 2025 - 12Z Thu 11 Sep 2025 ...Rain and wind threat across the Aleutians into the weekend followed by widespread moderate rainfall across the Southwest and western Mainland next week... ...Guidance Evaluation/Preferences... Models continue to show good agreement both with timing and placement of a cyclone which looks to move into the western Mainland by early Sunday. This system should quickly weaken early next week with shortwave energy progressing across the state. By Monday into Tuesday, a second deep cyclone will approach the western/central Aleutians and the models over the past day have generally shown better agreement. There is a strong consensus now for a deeper closed low (possibly with connection to Tropical Cyclone Peipah currently near Japan) crossing the Aleutians into the Bering Sea early in the week and reaching Southwest Alaska by next Wednesday/day 7. The GFS, however, is still noticeably weaker advertising a weaker shortwave and surface cyclone that tracks south of the Aleutians and into the Gulf. The WPC blend used a non-GFS consensus for this system. Uncertainty increases by late in the period as this system moves inland, with the ECMWF wanting to pull the system more northward, and the CMC slower and more eastward. Also a lot of uncertainty with another wave towards the Aleutians late period, which the ECMWF at this point is the most aggressive with. The WPC blend used a general model consensus for the first system/Day 4, and a non-GFS consensus with the second Days 5-6. By Days 7 and 8, increased the weighting of the ensemble means into the blend to account for increased uncertainty. ...Weather/Hazards Highlights... A prevailing storm track from the Aleutians toward western Alaska will continue to bring active weather with frequent rounds of wind and rain across these areas through the forecast period. The first cyclone crossing the Aleutians into the Bering Sea and eventually reaching the western Mainland by Sunday will continue to bring a period of possibly gale force winds and moderate to locally heavy rain to the western and central Aleutians into Saturday. The system will weaken as it moves inland, but will still bring windy and rainy conditions across parts of the Mainland from Sunday into Monday with some enhancement near favorable mountain ranges. The second cyclone behind this one will approach the Aleutians with another heavy rain and high wind threat for Sunday into Monday. Precipitation will advance eastward with time through the Peninsula and into the Mainland. Moderate to locally heavy rainfall is possible across parts of the eastern Peninsula and Southern Coast regions, with some mixed precipitation or snow in the highest elevations. Models remain very uncertain on how much rain will fall but at this point it looks to remain below criteria for including on the WPC hazards map. Rain will also be widespread next week across western and northern portions of the Mainland associated with this system. Temperatures will be above normal on Sunday across much of the state, with the highest anomalies over the North Slope region and Eastern Alaska. Temperatures across the North Slope will moderate and trend much colder by mid next week, with below normal temperatures more common across the state next week underneath of upper level troughing. Southeast Alaska and the Panhandle region will be dry and warm through much of the period. Santorelli 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