Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 623 PM EDT Mon Aug 2 2021 Valid 12Z Fri Aug 6 2021 - 12Z Tue Aug 10 2021 ...Overview and Guidance/Predictability Evaluation... An amplified and blocky ridge in place over mainland Alaska is forecast to slowly break down around the end of this week as a pattern change evolves during the medium range forecast period. The weakening ridge will then allow for troughing associated with a deep upper level low across the Bering Sea to drive a cold front across western Alaska. The Bering Sea low will meander across the region through most of the forecast period, while a couple of shortwaves/surface lows rotate around the base of the trough into the Aleutians. In terms of the model guidance, there remains above average agreement among the deterministic runs through about day 6, and then the CMC diverges somewhat and becomes faster with upper level height falls associated with the Bering Sea trough compared to the model consensus. The WPC forecast was based on a general deterministic model blend through Sunday, and then less of the CMC and more of the EC and GEFS means for early next week. ...Weather/Threats Highlights... Widespread showers are expected across western Alaska late this week as moisture surges northward ahead of the Bering Sea upper low. Going into the weekend, the moisture should begin overspreading the southern half of the state as a cold front moves inland. Periods of showers will continue to affect the Aleutians through next weekend associated with a couple of weaker embedded surface lows pivoting around the main upper level gyre over the Bering Sea. Temperatures across the state should be above average for most of the region underneath the upper level ridge. As the ridge begins to decay and troughing moves into the state by Friday, temperatures should quickly trend cooler into the weekend and early next week. Most of the North Slope region should be below normal as a shortwave drops southward from the Arctic Ocean. Hamrick 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