Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 707 PM EDT Fri Mar 21 2025 Valid 12Z Tue 25 Mar 2025 - 12Z Sat 29 Mar 2025 ...Overview... A broad upper low/trough is expected to encompass most of the Gulf region for the middle of the week, with a weakening surface low south of the Kenai Peninsula and a forming low over the eastern Gulf that will become dominant. This low should lift north and then northwestward into Friday and Saturday over the northern Gulf as a blocky upper level pattern becomes established. Meanwhile, an upper ridge becomes amplified over the Aleutians and over the southern Bering Sea going into the end of the week, with some potential shortwave energy crossing the Bering Sea north of the ridge axis. ...Guidance/Predictability Assessment... The ensemble means are overall in agreement on the large scale synoptic pattern across the domain in how the upper low evolves across the Gulf and the downstream upper ridge across the Aleutians and Bering Sea. However, the deterministic guidance disagrees on how shortwaves from eastern Siberia cross the northern periphery of the Aleutians ridge. The CMC and UKMET favor a stronger shortwave reaching Bristol Bay and the southwestern mainland around Thursday. In addition, the GFS becomes much stronger with a closed upper low crossing the Bering and reaching the western mainland around Friday, but its ensemble mean is not on board with this scenario, so it was tapered down in the forecast blend beyond Thursday. This also holds true for the UKMET and CMC solutions by Wednesday. Given the deterministic spread by next Saturday, the ensemble means accounted for about 2/3rds of the model blend by that time. ...Weather/Hazards Highlights... The southern coast and Panhandle will likely see periods of mainly light to moderate coastal rain and mountain snow on Tuesday in association with gradually weakening low pressure settling over the southern Gulf. A weakening front could provide precipitation to the Aleutians on Tuesday. Much of Alaska should be dry for midweek, but by late week, surface low re-development over the northern Gulf will likely result in additional rain and mountain snow for Southeast Alaska, though the details are yet to be determined. Expect temperatures to gradually moderate closer to normal by Tuesday and into Wednesday as the upper trough weakens. The North Slope and Brooks Range should be near average through much of next week, while the Interior and the Panhandle could see a mix of above and below normal temperatures. 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