Abstract
The occurrence of extreme low-level wind shear at 10 stations in the conterminous United States is investigated by applying a bivariate frequency-distribution analysis to rawinsonde and pibal data. Data for Denver, Colo., received additional analysis and showed that extreme wind shears were associated with particular synoptic conditions. Many stations indicated variation of extreme shear with season. Large values of extreme wind shear were found to correlate well with mean storm tracks in the conterminous United States.