Unrelenting heat wave bakes half the U.S.; 30 dead

Avery Gass, 4, slips her way through streams of cooling water, Friday, July 6, 2012, at the Thorton Murphy Park splash pad in Spokane, Wash. The National Weather Service says the high pressure system responsible for heat in much of the country is building into the Northwest this weekend. (AP Photo/The Spokesman-Review, Dan Pelle)