Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 758 PM EDT Tue Jun 27 2023 Valid 12Z Sat Jul 1 2023 - 12Z Wed Jul 5 2023 ...Synoptic Overview and Sensible Weather... A strong upper low just south of the eastern Aleutians Saturday morning is forecast to lift northward across the Alaska Peninsula and then Bristol Bay by Monday. A second upper low is expected to develop over the western Bering around this time and then pivot around the decaying upper low near southwestern Alaska. East of the big upper trough will be a downstream ridge axis extending across eastern mainland Alaska into the Yukon Territory. Much of the eastern Gulf region should also be under an upper ridge axis. The storm system lifting north across the Alaska Peninsula Sunday into early Monday is expected to produce heavy rain across the windward terrain from Kodiak Island to the Kenai Peninsula and portions of the Chugach Mountains, and then improving conditions going into Tuesday. Temperatures are expected to be mild across much of the Interior, with highs reaching well into the 70s and even some lower 80s possible across the Yukon Flats. Readings in the 50s and 60s are expected for the North Slope, and upper 40s near the Arctic Coast. ...Guidance Evaluation/Preferences... The 12Z model guidance suite, along with the 18Z GFS, are in good overall agreement on most synoptic scale features for the upcoming weekend, so a general model blend suffices as a starting point in the forecast process. Going forward into early next week, the ECMWF was the deterministic model closest to the GEFS/ECENS and thus was weighted slightly more than the CMC and GFS for Monday. By the middle of next week, the CMC was too weak with the second low pressure system south of the Aleutians and does not have much ensemble support, so it was not used by the end of the forecast period, and the use of the ensemble means increased to 60% by next Wednesday. Hamrick Hazards: - Heavy rain across portions of west-central mainland Alaska, Fri, Jun 30. - Heavy rain across portions of the Alaska Peninsula and the Kenai Peninsula, Sun-Mon, Jul 2-Jul 3. 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