Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 703 PM EDT Fri Jun 30 2023 Valid 12Z Tue Jul 04 2023 - 12Z Sat Jul 08 2023 ...Overview and Guidance Evaluation/Preferences... The period starts Tuesday with an upper low weakening over the eastern Bering Sea with a second developing system just south of the Aleutians. This second low should slide eastward near the Aleutians through about mid-week before it gets forced northward into Bristol Bay (in a weakened state) as upper ridging builds over the Mainland. Across the Interior and Northern Alaska, a weak trough should move through the region with additional lower heights later in the week due to a deep upper low over the Arctic. The guidance shows overall good agreement on the synoptic pattern through the period, but still some considerable uncertainty in the details and timing of the main low south of the Aleutians. The GFS is slightly faster and more east with the low, as compared to the 12z ECMWF and CMC, but this slightly eastern position has support in the ensemble means. The 00z ECMWF was in line with the 12z GFS but the 12z ECMWF came in slower (owing to stronger ridging over Mainland Alaska late period). There is also some disagreement in the strength of early period troughing over the Interior and Northern Alaska as well. Guidance showed good enough agreement the first half of the period for a blend of the latest 12z deterministic models. By days 7 and 8, blended in considerable amounts of the ensemble means given late period uncertainties and this provided a nice middle ground solution between the slower ECMWF/CMC and the faster GFS with the low pressure system crossing the eastern Aleutians/AK Peninsula. This approach maintains good continuity with yesterdays forecast as well. ...Weather/Hazards Highlights... Precipitation over Kodiak Island and the Kenai Peninsula should be waning by the start of the period/Tuesday though showers should continue through the Holiday. The next system should begin to usher in another round of moisture/rainfall with some potential for locally moderate to heavy rainfall (given slightly above normal moisture values), but still plenty of uncertainty in the details. Temperatures look to trend cooler across most of Alaska, with the exception of the North Slope, far eastern Interior, and southeast Alaska. Parts of the eastern interior of Alaska could be near 80F for most of next week. Santorelli Hazards: - Heavy rain across portions of mainland Alaska, Mon, 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