Alaska Extended Forecast Discussion National Weather Service College Park MD 632 PM EDT Tue Aug 19 2025 Valid 12Z Sat 23 Aug 2025 - 12Z Wed 27 Aug 2025 ...Guidance Evaluation/Preferences... WPC continued to prefer a heavier weighting of the CMC/ECMWF solutions for the blend since non GFS guidance have been persistent in the overall clustering and evolution of this synoptic pattern. The GFS has had multiple cycles where its more progressive than the EC and CMC with a deep and phasing trough over east Russia/the Bering Sea, along with more pieces of shortwave energy rotating around the base of the Arctic low. Days 4 and 5 began with a general model blend consisting of the 12z EC/GFS/CMC/UKMET with greater weighting on the EC and CMC. Ensemble means were integrated into the blend and increased in weighting through day 8. The Canadian and GFS signal another shortwave emerging over eastern Russia on days 7/8. This latter feature will need to continue to be monitored as it has potential to pack a punch to the western coastal areas in terms of surge/flooding and points inland with heavy rainfall. ...Weather/Hazards Highlights... Through the course of the coming week the Bering Sea will have ridging while a deep Arctic low will remain anchored with troughing/closed low in place over the Gulf of Alaska. Shortwave energy will likely rotate through the southern periphery of the Arctic low and kick-off an active period of precipitation across much of the mainland beginning Wednesday and continuing through the weekend. Diffluence ahead of potential phasing between a low emerging off of east Russia and the deep arctic system is expected to bring a substantial plume of moisture to the State late this week. This surge of moisture will likely include some of the remnant moisture associated with TD 18W. There is an increasing threat for heavy rain for the Brooks Range, Alaska Range and surrounding locations through the course of the week. High temperatures will likely remain average across the mainland, while widespread cloud cover will probably keep overnight temps above average. Temperatures across the panhandle will be above average late this week due to persistent troughing in the Gulf sending warm southerly air into the region. Campbell 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