The June 19, 2007 Delaware County flash flood : a meteorological and hydrological analysis

"A meteorological and hydrological analysis of an extreme flash flood event in central New York is presented. The meteorological analysis indicated that the environment associated with this event evolved to include many characteristics previously found with convective flash floods. Important elements included a moist atmosphere favorable for high precipitation efficiency, a strong low-level jet associated with significant moisture flux convergence over the flash flood zone, weak mid-level wind shear, and a thermal structure characterized by a tall, skinny convective available potential energy profile. The hydrological analysis indicated that extreme flash flooding occurred in small, steep, heavily forested stream basins with 3-hour rainfall that doubled the 24-hour 100 year rainfall extreme for the area. Minor flooding began when estimated rainfall totals exceeded 2.00 inches, while major flooding began when estimated rainfall totals exceeded 4.00 inches. Peak rainfall during this event eventually exceeded 10 inches. An estimation of the flow along one of the streams involved in the flood was in excess of a 500-year return flow, consistent with extreme rainfall rates. Brief, extremely rapid rates of rise on area streams were likely caused by debris pileups giving way behind high way bridges"--Abstract. Michael Schaffner, Michael Evans and Justin Arnott. "August 2008." Includes bibliographical references (pages 11-12). 2008 NWS (National Weather Service) ER (Eastern Region) Library Public Domain 1931