Introduction
During the afternoon of 17 May 1999, a long-track convective wind storm moved across the lower Ohio Valley. This storm satisfied derecho criteria (Johns & Hirt, 1987) which states that a derecho must:
1. The concentrated area of reports must have a major axis of at least 400 km (250 nm).
2. The reports must show a pattern of chronological progression.
3. There must be at least three (3) reports separated by 64 km (40 nm) or more, of either F1 damage and/or convective gusts of 33 m s-1 (65 kts) or greater.
4. No more than 3 hours can elapse between successive wind damage (gust) events.
