If you’re heading to any Yellow line destinations this weekend, including National Airport, you should make alternate plans. Metro is shutting down the Yellow line rail bridge over the Potomac River this weekend to do track maintenance and conduct an annual bridge inspection. The closure begins tonight at 10 p.m. and lasts through Sunday at midnight. Directions from WMATA: When a Yellow Line train arrives at the King Street Metrorail station, passengers must transfer to…