Alaska Extended Forecast Discussion National Weather Service College Park MD 520 PM EDT Sun Jun 29 2025 Valid 12Z Thu 03 Jul 2025 - 12Z Mon 07 Jul 2025 ...General Overview... The upper pattern will be characterized by a mild/stable upper level high over the North Slope/Brooks Range later this week and into/through the weekend. Between 50-55N, a few systems will traverse this latitude band which will keep the highest rain chances across the Aleutians and into the Panhandle. This pattern will be conducive to enhanced thunderstorms over the interior which may spark some fire concerns. ...Guidance Evaluation/Preferences... The 12Z model guidance suite was in relatively good agreement overall with the handling of the main upper features, with expected detail differences through the period. As with any blocky pattern, the biggest question is when and how the block breaks down. The dynamical models largely agree that the upper high will weaken but mostly remain in place by next week (day 8/Mon) and this was seconded by the ECMWF AI/ML guidance as well. To the south, there was much more spread in the timing/location of the upper low(s) out of the Bering and into the Gulf. By next Sun/Mon, the spread was extended west-to-east across ~30deg longitude with the placement of the lead and/or trailing upper low. The ECMWF AIFS was notably much farther west into the Bering by next Sun/Mon vs the most farthest east ECMWF control (ex-HRES), roughly forming the west/east bounds. While a consensus blend worked well to start (days 4-6), trended toward the ensemble means which were in between the two and more like continuity. ...Weather/Hazards Highlights... The upper high will promote mild/warm temperatures with isolated showers/storms for the North Slope/Brooks Range and much of the interior, with temperatures rising into the 80s in the warmest spots. Over the Tanana Valley, thunderstorm chances may increase by later in the week as anomalous easterly flow around the upper high increase instability when combined with warm/very warm surface temperatures. Thunderstorms without much rainfall could lead to fires started by lightning. Stratiform rain will be favored across the Aleutians and into the Panhandle (as well as skirting coastal Southcentral) as the Bering-Gulf systems move through from west to east. Rainfall amounts will be light to modest and temperatures will be near to a bit below normal due to the cloud cover. Fracasso 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