Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 626 PM EDT Fri Jun 02 2023 Valid 12Z Tue Jun 06 2023 - 12Z Sat Jun 10 2023 ...A stalled deep layer low will bring heavy rain and high winds to the Alaska Peninsula/Southcentral next week... ...Overview/Guidance Evaluation/Preferences... A consolidating upper low and its associated surface low reflection slowly positioning itself over the eastern Aleutians will be the main weather feature going into next across the Alaska region. With such a blocky pattern, there is relatively good agreement and higher confidence in the bigger picture details. Energy coming in from the west across the Bering Sea will combine with an existing piece of mid-level energy to consolidate into a large sprawling closed low. Overall, in the day 4-6 time frame, the deterministic guidance is in reasonably good agreement such that a near equal blend of the 12Z GFS, ECMWF, UKMET, and CMC was used in the preferred blend. By Day 7-8, some timing differences develop with the GFS being a bit faster to push the energy eastward and given the blocky pattern, it may end up being slower to erode or open up. The 12Z ECMWF does linger the closed low further west longer, so something to consider going forward. So for the Day 7-8 blend, higher weights of the EC and GEFS ensemble means were used while retaining some 12Z deterministic GFS and ECMWF. This led to a reasonable adjustment from continuity. Further downstream, model guidance is increasing its signal for a bout of ridging to develop over Southeast Alaska and then extend northward/northwestward through the northern Mainland next week. ...Sensible Weather and Potential Hazards... The heaviest precipitation amounts next week will be from the Alaska Peninsula into Southcentral Alaska and the Kenai Peninsula, as the strengthening deep layer cyclone over the Aleutians brings increasing moisture in the form of an atmospheric river channeling moisture from what is currently Tropical Storm Mawar in the western Pacific. Precipitation is expected to begin early next week and last for several days, accumulating to several inches in Southcentral Alaska. Mainly rain is likely though some precipitation could be snow in the highest elevations. Strong winds could also be a threat ahead of the lows especially over marine and adjacent areas, with favored gap wind areas increasing wind speed. Some rain may spread into Southeast Alaska with time. A warming trend is in store for areas north of the Alaska Range next week after a cool period in the short range, as the upper troughing over the northern Mainland lifts out and warm front moves north. Temperatures should generally warm to above average next week in the lower elevations, though the higher elevations of the Brooks Range may take longer to moderate. Afternoon highs will likely rise into the 70s for lower elevations of the Interior for with lows perhaps staying in the low 50s by midweek. However, the upper low and the coincident rain and cloudiness chances could keep high temperatures down below normal along the southern coastal regions. Southeast Alaska may warm somewhat around Tuesday-Wednesday, but could cool again by late next week depending on whether the upper low's influence extends that far east. Tate/Taylor Hazards: - Heavy rain across portions of mainland Alaska, Mon-Wed, Jun 5-Jun 7. - High winds across portions of mainland Alaska, Mon-Tue, Jun 5-Jun 6. 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