Alaska Extended Forecast Discussion National Weather Service College Park MD 645 PM EDT Mon Aug 4 2025 Valid 12Z Fri 08 Aug 2025 - 12Z Tue 12 Aug 2025 ...Synoptic Overview... A messy and unsettled forecast coming up across Alaska this weekend into the upcoming workweek. A large longwave trough will establish itself across much of the state through the period. However, embedded lows are being poorly handled by the guidance, rapidly introducing uncertainty to the forecast. An upper level low over Kodiak Island starts out the forecast, with a secondary trough over the Arctic Ocean. The Arctic trough will dig southward as an upper level low moves out of the Arctic and down the Bering Strait. As it does so, the low will likely open up into a trough, though that too is uncertain. By Saturday, the low over Kodiak itself opens up into a trough, but one that digs as the energy from the trough digging south down the west coast merges with North Pacific energy, resulting in a digging trough across the North Pacific, south of the Aleutians. The result will be a highly amplified trough, with potential upper lows embedded at 2 different points therein. As the North Pacific energy rounds the base of the trough, a low will develop along it, able to tap into some subtropical moisture due to starting at a low latitude. The low will quickly ride northeast up the front of the trough into the Gulf, and into the Panhandle by this weekend. Due to the complexity in the upper level pattern, how this low behaves...whether it beelines into the coast or stalls out and weakens over the northern Gulf remains to be seen, but regardless, the result will be a very wet weekend for much of the Gulf Coast. Consensus is for the low to stall out over the Gulf, resulting in a prolonged period of onshore flow, and hence wet weather, for the Panhandle, although except in favored upslope areas, the rain should not be all that heavy since the low is weak. Across Northern Alaska, uncertainty with the upper level features, but good agreement on the establishment of a deep trough, should result in a much cooler and cloudy period across the entire state. Periodic light rain should help to end the fire season. Cooler air over the Arctic Ocean is likely to remain there as a large upper low establishes itself well north of Utqiagvik. This should allay earlier fears of termination dust on most of the Brooks Range in favor of a cold rain for most areas. For the Aleutians, high pressure builds over the western Aleutians Friday, to be replaced by the next NPac low on Saturday, which elongates across the western and central Aleutians through Monday. No atypical conditions are expected as a result of this low. ...Guidance Evaluation and Preferences... The guidance is in poor agreement overall on much of the forecast. Agreement is mostly in that a large and deep longwave trough will establish itself across the entire state, resulting in a wet, cooler, and gloomy forecast statewide. However, individual lows embedded within the trough are highly uncertain in their track, which could allow for conditions in some areas to allow for brief periods of relatively sunny/clear and quiet weather. The model blend included a heavier blend towards the foreign models than usual in the shorter range, transitioning to a heavier than normal ensemble blend for days 7 and 8 (Mon and Tues). ...Weather/Hazards Highlights... The primary hazard to watch out for through the period is a worsening of potential glacial outburst flooding from the Mendenhall Glacier this weekend as a period of wet weather is expected throughout the Friday through Tuesday period. Rain will be light most of the time, but depending on the timing, track, and strength of any North Pacific lows that make their way to the Panhandle, it's possible that narrow, training bands of heavier rain could impact much of the Panhandle at various times this weekend. Elsewhere, the weather looks very typical for this wet season time of year for much of the state, with any remaining fires in the interior ending as a cooler, wet pattern is established. && Wegman 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