Southwest Airlines will add five daily nonstop routes to its schedule this fall. Two of the new routes will depart from the carrier’s base at Houston Hobby, where daily nonstop service to Columbus, Ohio, and Louisville will begin Oct. 3. Additionally, Southwest will add daily nonstop service between Denver and Memphis, also beginning Oct. 3. The carrier will offer one roundtrip flight each weekday on all three routes. Two other routes – Oklahoma City-Nashville and Denver-El Paso – will get Sunday-only nonstop service beginning Oct. 7. Also, Southwest is beefing up its service from Phoenix, adding two additional weekday flights to San Jose and one each to Denver, New Orleans, San Antonio and Austin – all beginning Oct. 3.