Southwest Airlines will launch new nonstop service between Austin and San Francisco in August. The airline will operate daily nonstop flights beginning Aug. 5. As of now, customers can book flights up to Oct. 1. It’s unclear at this time if the route will be extended to year-round service or if the seasonal route will end after the summer. The route announcement comes less than three months after rival Delta Air Lines said it would start flying nonstop between Austin and San Francisco in June.…