thunder run
n.— «The Kern is designated a national “Wild and Scenic River.”…That is followed by the Upper Kern, a series of several defined runs. The last takeout is at Riverside Park in town. The sections vary from Class III to IV, with one Class V portion—Thunder Run.» —“The Other Side of the Kern ‘March Miracle’ Means Plenty of Water, but Plenty of Water Means Danger” by Rich Roberts Los Angeles Times June 19, 1991. (source: Double-Tongued Dictionary)