Alaska Extended Forecast Discussion National Weather Service College Park MD 728 PM EDT Fri Sep 19 2025 Valid 12Z Tue 23 Sep 2025 - 12Z Sat 27 Sep 2025 ***Rain and wind for Southeast Alaska early in the week, followed by another Gulf low a few days later*** ...General Overview... The low pressure system that will initially be over the northern Gulf Tuesday morning is forecast to steadily weaken going into Wednesday with a temporary abatement of rain and wind. A well- developed occluded surface low over the Bering Sea rapidly tracks east through Thursday, with a secondary low forming after crossing the Alaska Peninsula and becoming the dominant low over the Gulf for the end of the week. Meanwhile, an amplifying trough over eastern Siberia should support a cold front that could approach western Alaska by next Saturday. ...Guidance Evaluation/Preferences... The 12Z model guidance suite featured good overall synoptic scale agreement for Tuesday, and therefore a multi-deterministic model blend works well as a starting point. By Wednesday, the ECMWF and CMC have a stronger trailing secondary shortwave behind the Bering Sea low that merges into the primary low center. Overall, there has been a slightly faster trend with today's guidance with the low track compared to yesterday. Looking ahead to the end of next week, the GFS becomes faster with the eastern Siberia low, and the CMC is stronger with surface high pressure south of the Aleutians compared to the model consensus. The CMC/ECMWF maintain a stronger low solution near northwest mainland Alaska by next Saturday, which could result in even colder conditions and wintry precipitation going into next weekend, so this will be something to monitor going forward. The ensemble means were gradually increased to about half by the end of the forecast period. ...Weather/Hazards Highlights... The low pressure system stalling in the Gulf early next week is expected to direct a plume of moisture at Southeast Alaska, and heavy rainfall is expected there, where several inches of rainfall are expected through Tuesday. In addition to heavy rain, high winds are expected along the Southeast Coast as southerly winds ahead of the system are enhanced by the barrier jet along the shoreline. Strong, gusty winds over the near shore waters will create hazardous boating conditions Monday into early Tuesday. The next low pressure system will also bring potential for hazardous weather for southern coastal areas of Alaska towards the middle to end of next week. High winds are expected along the Aleutians Tuesday through Wednesday as the system strengthens over the Bering Sea. The low could bring another threat of localized heavy rain to South-Central and Southeast Alaska on Thursday into Friday. In terms of temperatures, colder conditions will be commonplace across most of the mainland, with subfreezing overnight lows becoming more widespread across the Interior by the middle of next week. Temperatures will likely level off by mid-late week across most of the state as the cold air advection decreases by that time. There may be a renewed surge of colder conditions by next Saturday over northwestern Alaska depending on how the low near eastern Siberia evolves. Hamrick 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