Searing heat across most of the nation was punctuated by thunderstorms along the Gulf Coast, from Lake Michigan to the central Appalachians and over part of the Rockies, where temperatures hit record highs along the eastern edge. High winds downed trees and power lines west of Philadelphia, Miss., and damaged several farm buildings. South Bend, Ind., got 3.65 inches of rain, enough to cause street flooding. Houston got a half-inch of rain in 20 minutes. Readings were above 100 degrees over southeastern South Dakota, southwestern Nebraska and the desert Southwest. Denver posted a record high of 98 and Cheyenne, Wyo., had a record high of 96.