Alaska Extended Forecast Discussion National Weather Service College Park MD 755 PM EDT Mon Sep 22 2025 Valid 12Z Fri 26 Sep 2025 - 12Z Tue 30 Sep 2025 ***Unsettled weather pattern continues for southern and southeast Alaska with multiple rounds of rain and mountain snow*** ...General Overview... The organized low pressure system that will be crossing the Bering Sea and Aleutians is expected to reach the northern Gulf by Thursday, with strong onshore flow and enhanced rain and mountain snow from the Kenai Peninsula to southeast Alaska to close out the work week. An amplified shortwave dropping southeastward from eastern Siberia is likely to cross the southwestern mainland and re-energize the existing Gulf low for the weekend. A third system will likely approach the Aleutians going into Sunday and Monday, and an arctic trough is likely to persist for the northern third of the state as well. ...Guidance Evaluation/Preferences... The 12Z models have come into better overall agreement compared to yesterday's major differences during the Day 4 through 6 time period. All of the deterministic models now have a closed low near 522dm in the vicinity of the Alaska Peninsula, and the AIFS has trended stronger since yesterday. Elsewhere, the CMC and ECMWF are stronger than the GFS with the initial low near southeast Alaska on Friday before dissipating. By early next week, major differences are apparent in the guidance regarding the overall pattern and the arrival of the next storm system. The GFS is out of phase over the eastern Aleutians by having a surface high over the region, whereas the non-NCEP guidance is more supportive of a low pressure system, and the AIFS has a potentially strong low by Monday morning approaching the Alaska Peninsula, so a non-GFS approach works best for Monday and Tuesday. Given the increased uncertainty in the deterministic guidance, more reliance was placed on the ensemble means for this forecast package by early next week, accounting for about 70% of the blend by next Tuesday. ...Weather/Hazards Highlights... The next low pressure system will bring the likelihood for more unsettled weather for southern coastal areas of Alaska towards the end of this week. There may be a brief abatement in precipitation before the next organized system arrives for the weekend, bringing periods of rain and mountain snow from the Kenai Peninsula to the southeast Panhandle. Stronger winds are also expected to develop over the inland passages as the southeasterly flow intensifies. Although the rainfall is not expected to be particularly heavy on any given day, the duration of moderate to heavy rainfall across the southeast was enough to warrant an area on the WPC medium range hazards graphic. There is also a third system to watch that may track close to the Aleutians late in the period, and this could be the eventual remnants of what is currently Typhoon Neoguri. In terms of temperatures, colder conditions will be commonplace across most of the mainland, with subfreezing overnight lows widespread across the Interior, and 10s to low 20s near the Brooks Range. The greater Anchorage area may have overnight lows that approach the freezing mark at times, and locations near the Pacific coast in the low-mid 40s. 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