Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 600 PM EDT Mon Jul 08 2024 Valid 12Z Fri Jul 12 2024 - 12Z Tue Jul 16 2024 â€Heavy Rainfall Threat from Southwest to Southern Alaska Friday-Sunday†...Overview and Guidance Evaluation/Preferences... The latest guidance solutions seem reasonably well clustered Friday into Sunday to cover an active period of Alaskan weather in an overall amplified and dynamic flow pattern. Prefer a 12 UTC GFS/ECMWF/UKMET/Canadian composite blend. Opted to switch to best compatible and cycle to cycle run consistent 12 UTC GEFS/ECMWF ensemble means by early next week amid growing forecast spread and uncertainty. This forecast plan maintains good WPC product continuity and tends to offer system detail consistent with individual predictability. WPC manual edits were applied to better depict the strength of the main organized surface systems that seem to have the most favorable mean upper support as an offset to inherent smoothing from the blending process. ...Weather/Hazards Highlights... A wavy and slow moving surface front may linger across the Interior and provide a weakening focus for scattered local precipitation over the next week. Much of the rest of Alaska should be quite wet and unsettled, which should also help bring some relief to wildfire activity. Models and ensembles continue to show an amplified and slowly evolving larger scale pattern with a major closed upper low/trough centered over the Bering Sea and an emerging upper trough over the Gulf of Alaska as ample energy fuels cyclogenesis and frontogenesis. In this scenario, heights rise at least temporarily overtop into the eastern Interior to moderate short range cooling before retreating. Around the periphery of the ridge, this pattern favors a continued wet and storm system active period out from the Arctic Ocean into the Bering Sea, with inland impacts from West/Southwest Alaska through the Alaska Peninsula/Kodiak Island, SouthCentral and then Southeast Alaska late week through next weekend. Storm systems will remain prone to develop and evolve/linger over the eastern Bering and downstream into the Gulf of Alaska. This portends a protracted period with potential for cummulative heavy rain, with some 1-2"+ daily totals set to steadily add up over the course of this forecast period to monitor for any runoff issues, especially over favored terrain. Pattern evolution and embedded system specifics seem a bit more muted into early next week in guidance, but the flow does offer some room for renewal to monitor. Schichtel 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