Alaska Extended Forecast Discussion National Weather Service College Park MD 706 PM EDT Tue Jul 22 2025 Valid 12Z Sat 26 Jul 2025 - 12Z Wed 30 Jul 2025 ...Overview... A closed upper low within an elongated trough will be tracking into the Gulf of Alaska is expected to deepen over the weekend. An associated surface frontal system will usher in a few rounds of precipitation for the Alaska Range southward along the southern coast to Southeast. The lows will be slow to move in the blocky pattern with an upper high north of the state, lasting into early next week while gradually weakening. Meanwhile upper ridging is forecast to reorient from the northern Pacific and build northward across the Aleutians and Bering Sea, causing temperatures to warm from west to east. ...Guidance Evaluation/Preferences... The latest suite of guidance continues to be in good agreement, especially for the weekend and the start of the coming week. The pattern is quite blocky with an upper high over the northeast Pacific and another in the Arctic Ocean, with Alaska's upper trough/low in between. The primary upper low emerging into the Gulf is fairly clustered through the early and mid periods with spread increasing as it meanders into next week. The GFS was noted to be on the north/east side of the cluster which would suggest higher QPF to the Pandandle and parts of the southern Coast for later in the period. Models also align well regarding ridging aloft and at the surface from the northern Pacific northward into the Aleutians and southern Bering Sea through much of the period. Broader model differences persisted early next week with the possibility of upper troughing emerging from eastern Siberia and the Arctic Circle to the west of the Beaufort Sea upper high. This would impact how much the ridge would displace/weaken and the length of time for this change. Models and ensemble members generally show some troughing reaching at least the Seward Peninsula if not to the Y-K Delta by Monday-Tuesday. This will likely continue to be a forecast challenge in future days. The WPC forecast used a multi-model blend with heavier weighting toward the ECMWF and GFS early to mid period. As the forecast progressed, used some GEFS and EC ensemble means in the blend and reduced the proportion of individual models, reaching just over half ensemble means by Day 8 given the increasing model spread. ...Weather/Hazards Highlights... Over the weekend precipitation is expected to focus in the Alaska Range and Southcentral into Southeast Alaska over the weekend and early next week with the upper and surface lows nearby. Appreciable rainfall totals over the course of multiple days however, Wet snow is possible in higher elevations of the Alaska Range. A front approaching, along with potential upper troughing coming into the Bering Sea and vicinity, could lead to rain chances across the Alaska Peninsula and western Mainland into next week, possibly spreading east across the Mainland. Temperatures will be on the rebound back towards normal over the weekend for much of the Mainland as upper ridging builds. Daily maximums will generally be in the 70s in most Interior areas. Temperatures may cool back down in the western Mainland early next week depending on the evolution of the upper trough. Southeast Alaska can expect temperatures to remain near to below average with the low in the vicinity and increased cloud cover. Campbell/Tate 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