Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 659 PM EDT Thu Jul 29 2021 Valid 12Z Mon Aug 02 2021 - 12Z Fri Aug 06 2021 ...Overview and Guidance/Predictability Evaluation... The latest guidance continues to indicate a blocky upper level ridge building over the mainland Alaska next week which should keep amplified troughing across the Bering Sea as well as an upper trough/closed low meandering in the Gulf. The guidance shows good agreement early on regarding a deep cyclone developing in the Bering Sea, but plenty of uncertainty thereafter on the details regarding individual shortwaves rounding the base of the upper low to send low pressure areas into the Aleutians. Regardless of the details, the guidance does agree on the large scale that low pressure will be maintained in some form over the Bering Sea through next week. Models also show some disagreement on how quickly the ridge over the Mainland may begin to break down which could help nudge the Bering Sea (and also low pressure in the eastern Gulf of Alaska region) just slowly eastward. Given the uncertainty, the WPC blend trended towards the ECENS and GEFS ensemble means by the second half of the period. This also maintains pretty good continuity with the previous forecast. ...Weather/Threats Highlights... Plenty of moisture streaming northward ahead of the Bering Sea trough will allow for wet and unsettled weather to continue during the first half of next week across portions of western and northern Alaska. Heavy rainfall over the weekend may linger into Monday, but coverage and amounts should be decreasing by the beginning of the extended range period with lighter rainfall lingering into Tuesday and Wednesday. A cold front pushing into the western Mainland by Wednesday should help bring some moisture into southern Alaska as well. Moderate to locally heavy rainfall is also possible across portions of the Panhandle region as a closed low lingers in the eastern Gulf. A building upper level ridge should bring temperatures above to well above normal across much of Alaska early next week. The exception to this will be across the North Slope region which should remain on the cold side of a quasi-stationary boundary. Temperatures elsewhere should begin trending back towards or below normal by the latter half of the week, dependent on how quickly the ridge begins to break down and lower heights sneak into the region. Santorelli Hazards: - Heavy rain across portions of western mainland Alaska, Sun, Aug 1. 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