Alaska Extended Forecast Discussion National Weather Service College Park MD 746 PM EDT Wed Jun 25 2025 Valid 12Z Sun 29 Jun 2025 - 12Z Thu 3 Jul 2025 ...Guidance Evaluation/Preferences... The 12Z model guidance suite is in reasonably good agreement for the beginning of the period Sunday, but model differences become more apparent going into early next week, especially across western portions of the domain where the eventual remnants of T.D. Sepat will go. There is general agreement for a building upper ridge across the mainland and a trough over the Gulf and Aleutians, with models varying on specifics. The use of the ensemble means were increased to about half by next Thursday. ...Weather/Hazards Highlights... A broad upper level low with reinforcing surface lows will be present across the northern Gulf through most of the forecast period. The upper ridge axis appears likely to build back in north across the central and northern mainland going into the middle of next week and potentially forming a rex block type pattern as a closed upper high could form. Meanwhile, a trough approaches from eastern Siberia Tuesday into Wednesday, but does not appear to be all that impactful at this time. Much of the mainland will start off dry for Sunday, but there will likely be an increase in shower and thunderstorm coverage going into early next week across eastern portions of the Interior. Relatively moist northeasterly flow approaching the central and eastern portions of the Alaska Range will increase the potential for heavier rainfall, with the highest totals where there is an upslope flow component where 1 to 2 inches will be possible. Therefore, after consultation with the local forecast offices, a heavy rainfall area has been introduced on the WPC hazards chart for the 29th and 30th for east-central portions of the Interior. This rainfall would help to mitigate any ongoing fire weather concerns. Off and on showers are also expected for southeast Alaska as moist onshore flow continues courtesy of the loitering low over the northern Gulf. 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