The addition of larger aircraft and more flights this summer is expected to help the Portland International Jetport rebound from its below-average performance in the first half of the year. Because the airport is usually twice as busy in the summer as the winter, increased passenger counts this season will allow the jetport to make up the ground it lost because of severe weather over the winter months, said Paul Bradbury, director of the city-owned airport. “If I have a killer August, it more than makes up for January and February,” he said. The upcoming holiday period is expected to be a typical summer weekend for the jetport.