Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 747 PM EDT Mon May 1 2023 Valid 12Z Fri May 5 2023 - 12Z Tue May 9 2023 ...Synoptic Overview... A synoptic scale upper trough is expected to be in place across western Alaska and the northern Bering for the end of this week, and a broad trough over the Gulf of Alaska with an embedded closed low aloft that gradually drops towards the southeast. Meanwhile, upper level ridging across western Canada likely extends to far eastern Alaska with a likely closed high over the Northwest Territories, and a closed low west of the Pacific Northwest, forming a potential Rex block pattern by Sunday. A second area of low pressure is likely to develop across the western Aleutians late in the forecast period with a ridge axis situated over the eastern Bering and far eastern Siberia, but details on that are indeed quite uncertain. ...Guidance Evaluation/Predictability Assessment... The 12Z/18Z model guidance continues to struggle with the evolution and timing of multiple shortwave perturbations tracking across the North Pacific. Differences are noteworthy as early as Friday south of the Aleutians, but reasonable over mainland Alaska. Models diverge even further going into the weekend with very poor agreement on the eventual evolution of the next storm system tracking near the Aleutians, and also unclear on the low over the southeastern Gulf. Given the well below average confidence, the forecast relied heavily on the ensemble means for Saturday through Tuesday along with small contributions from the 12Z GFS and ECMWF. It is important to note that major changes in the current forecast are likely going forward in the coming days as the model signal becomes more refined in future forecast cycles. ...Weather/Hazard Highlights... The occluded surface low passing well south of the southern mainland coast is expected to produce locally moderate precipitation across the favored terrain of the Alaska Peninsula, Kodiak Island, and the Kenai Peninsula on Friday. With that low dropping farther south and away from the state by the weekend, the intensity of the rain and mountain snow diminishes in intensity and coverage with mainly light precipitation expected going into the weekend for the coastal mountain ranges. Depending on the eventual track of the next low pressure system, parts of the eastern Aleutians and the Alaska Peninsula may see a return to more rainfall by Monday. In terms of temperatures, daytime highs in the 45 to 55 degree range 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 lower 30s, 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