Chris KornelisThe sky opened up a bit during Cold War Kids’ early-afternoon set, and the floor of Memorial Stadium turned into a garden of umbrellas. The rain has since subsided. For now.Who: Cold War KidsWhen: 1 p.m., Sunday, Sept. 6 (I missed the first third of the set.)Where: MainstageNote: The band played a pair of songs lead singer Nathan Willett said will show up on a forthcoming EP. They are: “Coffee Spoon,” and “Santa Anna Winds”There’s more energy and power in the restraint that this quartet displays in the slow jam, “We Used to Vacation,” than in anything I see in their more boisterous contemporaries. At their best, the band is an unselfconscious pop act adept at pushing to the brink of chaos, and reigning it back before catastrophe. At their worst, they wander close to insincerity. This afternoon was mainly the former.For all our festival coverage, visit Bumbershoot.SeattleWeekly.com.