| Abstract: | Widespread thunderstorms associated with two major squall lines, moved across Pennsylvania between the afternoon of July 19 and morning of July 20, 1977. The western part of outflow boundary produced by the second line became almost stationary in western Pennsylvania and resulted in 6 to 9 hours of nearly continuous thunderstorms. More than 6 inches of rain fell over a 400-square-mile area during this period. In the hills just north and east of Johnstown, rainfall totals were as much as 12 inches. Flash flooding was severe as the storms moved slowly southeastward across the Allegheny, Susquehanna, and Potomac River basins. Peak natural runoff rates greater than 1,000 cubic feet per second per square mile were common for streams draining up to 10 square miles. At eight gaging stations, recurrence intervals for the peak discharges were estimated to be 100 years or more. In addition to high surface runoff, some disasterous flooding also resulted from the failure of seven earthfill-gravity-type dams. At least 78 deaths were attributed to the flooding and eight persons were still listed as missing 1 year later. Total damages in the eight-county flood area were extremely high, possibly exceeding $500 million. |
| Genre: | USGS Numbered Series |
| ProdID: | 38601 |
| Citation Author: | Hoxit, L. Ray; Maddox, Robert A.; Chappell, Charles F.; Brua, Stan A. |
| Citation Contributing Office: | U.S. Geological Survey |
| Citation Datum: | |
| Citation Day: | |
| Citation Edition: | - |
| Citation Editor: | |
| Citation End Page: | |
| Citation Issue: | |
| Citation Keywords: | |
| Citation Language: | ENGLISH |
| Citation Larger Work Title: | |
| Citation LatN: | 0413000 |
| Citation LatS: | 0393000 |
| Citation LonE: | -0774500 |
| Citation LonW: | -0800000 |
| Citation Month: | |
| Citation No Pagination: | N |
| Citation Number Of Pages: | |
| Citation Online Only Flag: | |
| Citation Phsyical Description: | vi, 68 p. |
| Citation Projection: | |
| Citation Public Comments: | Prepared jointly by the U.S. Geological Survey and the National Oceanic and Atmospheric Administration |
| Citation Publisher: | U.S. Geological Survey |
| Citation Series: | Professional Paper |
| Citation Series Code: | PP |
| Citation Series Number: | 1211 |
| Citation Search Results Text: | Johnstown-Western Pennsylvania Storms and Floods of July 19-20, 1977; 1982; PP; 1211; Hoxit, L. Ray; Maddox, Robert A.; Chappell, Charles F.; Brua, Stan A. |
| Citation Start Page: | |
| Citation Volume: | |
| Citation Year: | 1982 |
| Type: | citation/reference |
| Text: | Johnstown-Western Pennsylvania Storms and Floods of July 19-20, 1977; 1982; PP; 1211; Hoxit, L. Ray; Maddox, Robert A.; Chappell, Charles F.; Brua, Stan A. |
| URL (THUMBNAIL): | http://pubs.usgs.gov/pp/1211/report-thumb.jpg |
| URL (DOCUMENT): | http://pubs.usgs.gov/pp/1211/report.pdf |
| Date Other: | Sat, 1 Jan 1994 00:00 -0600 |
| Publisher: | U.S. Geological Survey |
