Meteorology Commons^™

Incorporating Uh Occurrence Time To Ensemble-Derived Tornado Probabilities, Burkely T. Gallo, Adam J. Clark, Bryan T. Smith, Richard L. Thompson, Israel Jirak, Scott R. Dembek

United States Department of Commerce: Staff Publications

Probabilistic ensemble-derived tornado forecasts generated from convection-allowing models often use hourly maximum updraft helicity (UH) alone or in combination with environmental parameters as a proxy for right-moving (RM) supercells. However, when UH occurrence is a condition for tornado probability generation, false alarm areas can occur from UH swaths associated with nocturnal mesoscale convective systems, which climatologically produce fewer tornadoes than RM supercells. This study incorporates UH timing information with the forecast near-storm significant tornado parameter (STP) to calibrate the forecast tornado probability. To generate the probabilistic forecasts, three sets of observed climatological tornado frequencies given an RM supercell and STP …

Thunderstorms And Tornadoes Of February 1, 1955, Jean T. Lee

NOAA Technical Reports and Related Materials

The purpose of this paper is to describe and illustrate some of the features that are of particular interest in the forecasting of one of the most death-dealing series of convective storms of the 1950s that occurred during the afternoon and evening of February 1, 1955. This series of severe storms included tornadoes, destructive winds, hail, and heavy rain that first struck near Marianata, Arkansas, then roared through Commerce Landing, Mississippi and northern Mississippi. then moved on to near Huntsville, Alabama.

Includes features at the surface, at 850 mb, 700 mb, and 500 mb, and upper air conditions, along with …