Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 726 PM EDT Sat Apr 29 2023 Valid 12Z Wed May 3 2023 - 12Z Sun May 7 2023 ...Overview... A synoptic scale upper trough is expected to be in place across western Alaska and the northern Bering for the middle of the week, and quasi-zonal flow south of the Aleutians. This trough then builds southward across the Gulf of Alaska going into the end of the week along with an occluded surface low. Meanwhile, upper level ridging across western Canada likely extends to far eastern Alaska Friday and going into the weekend. A second area of low pressure is likely to develop across the western Aleutians late in the forecast period. ...Guidance Evaluation/Predictability Assessment... The 12Z model guidance has a reasonable synoptic scale depiction of the weather pattern going into the middle of the week, with the greatest differences noted across the western Aleutians and Bering Sea. Notable differences are apparent as early as Thursday across the North Pacific, and the GFS becomes stronger with the trough building south of mainland Alaska and stronger with a low over the Aleutians. By the weekend, the guidance is still struggling with shortwave energy moving east from Siberia and also across the Gulf region, although there is a general signal for a building upper ridge over the eastern Bering and a trough over the southern Gulf. Given the uncertainty, more of the ensemble means were included by Friday and beyond, and then all ensemble means by next Sunday. ...Weather/Hazard Highlights... The heavy precipitation that is expected on Tuesday across the coastal mountain ranges of the southern mainland is forecast to abate some going into Wednesday as the onshore flow associated with the southwestern Alaska surface low weakens. Some resurgence of moisture from the Gulf is probable going into Thursday across the favored terrain of the Alaska Peninsula, Kodiak Island, and the Kenai Peninsula as the next Gulf low organizes. With that low dropping farther south and away from the state by Friday and beyond, the intensity of the rain and mountain snow diminishes once again with mainly light precipitation expected by that time. In terms of temperatures, daytime highs in the 40s to low 50s can be expected most days for locations south of the Brooks Range, and still quite chilly for the North Slope and Arctic Coast, likely remaining below freezing with highs mainly in the 20s to low 30s. Most inland locations will likely have overnight lows in the 20s, and 10s north of the Brooks Range. 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