Alaska Extended Forecast Discussion National Weather Service College Park MD 701 PM EDT Sun Jul 20 2025 Valid 12Z Thu 24 Jul 2025 - 12Z Mon 28 Jul 2025 ...Overview... Elongated upper troughing is forecast to stretch across much of Alaska at the start of the period Thursday with embedded upper lows. This will lead to some precipitation and cooler temperatures across most of the state. By next weekend, consolidating energy should yield a deepening upper/surface low in the northeast Pacific that is slow to move in the blocky pattern, which could lead to rounds of precipitation along the southern coast to Southeast Alaska. 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... Individual model and ensemble guidance is pretty agreeable with the large scale pattern described above. 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. On Thursday models show an embedded upper low atop the Bering Strait with troughing stretching southeast and possibly another low near Southeast. The primary upper low is forecast to slowly track in the direction of the trough. There is some model spread with the details of the lobes of vorticity within the broad trough, but nothing out of the ordinary for the extended range. No particular outliers were seen, aside from the UKMET by Friday-Saturday that again showed combining energies near the Chukchi Sea that prevented the upper low from diving southeastward like the other guidance. Models are agreeable with the upper and surface lows deepening by next weekend when they reach the northeast Pacific/Gulf of Alaska. Still just minor spread with the position of these features, though did lean away from the recent GFS runs that were positioned a bit east closer to land compared to the better AI/operational model/ensemble mean consensus to the west. Meanwhile upper ridging is forecast to build over the Aleutians and Bering Sea, as the southeastward moving upper low reorients the northeast Pacific upper high to the west. The WPC forecast used a multi-model blend of the GFS, ECMWF, and CMC 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 (especially the GFS) to about half models/half means by Day 8. This solution generally showed good continuity from yesterday's forecast. ...Weather/Hazards Highlights... Moderate to heavy precipitation may be ongoing into Thursday across the Copper River Basin and Alaska Range, as a couple of low pressure/frontal systems focus moisture in those areas. Meanwhile another front or two will promote increasing precipitation chances across the Y-K Delta Thursday and moving into the Alaska Range and Southcentral late week. Rain amounts look to stay moderate rather than be heavy/hazardous. The Brooks Range may see light to moderate precipitation through late week. Wet snow is possible in the higher elevations of both the Brooks and Alaska Ranges. The rain chances combined with cooler temperatures should help ease fire weather conditions in the Interior late this week, until the warming and drying trend north of the Alaska Range by early next week. Over the weekend and early next week, most precipitation will occur from the Alaska Range southward as the surface and upper lows restrengthen in the northeast Pacific. Precipitation should linger in Southcentral Alaska while Southeast Alaska could start to see moderate to heavy precipitation. Meanwhile, the eastern Aleutians/Alaska Peninsula can expect rounds of light to moderate rain. Temperatures will be below normal for much of the Mainland into late week due to the lower heights aloft. Highs should generally be around 5-15 degrees below average, with lows less anomalous. Maximum temperatures will be in the 50s and 60s for most areas. Southeast Alaska (the Panhandle) can expect near to below average temperatures after a warm early week period. As the upper ridge builds atop the Aleutians to Bering Sea behind the main upper low, most of the Mainland should see a warming trend from west to east over the weekend into early next week, bringing Interior areas into the 70s. 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