Conditional Probability of a Significant Tornado (Eqn 1)

Contour analysis of conditional significant (EF2+) tornado probabilities that are estimated via two forms of a linear regression equation. The probability is conditional on the occurrence of a supercell thunderstorm. The components of the significant tornado parameter (STP) make up the basis of the two regression equations, both of which use a product of the 0-6 km bulk wind difference and the square root of MLCAPE,and MLCIN. The primary variation between the two conditional probability equations involves the use of 0-1 km SRH (equation 1) and the 0-1 km bulk wind difference (equation 2). The conditional probabilities tend to overestimate the rate of occurrence of signficant tornadoes,especially where the initial convective mode is nondiscrete, or where the mode evolves from discrete to linear. The regression equations complement the STP in a probabilistic sense, and overall performance is similar to the STP.

For additional information, please refer to:

Togstad, W. E., J. M. Davies, S. J. Corfidi, D.R. Bright, and A. R. Dean, 2011: Conditional probability estimation for significant tornadoes based on Rapid Update Cycle (RUC) profiles. Wea. Forecasting, 26, 729-743.