Tornado intensity estimated from damage path dimensions

PLoS One. 2014 Sep 17;9(9):e107571. doi: 10.1371/journal.pone.0107571. eCollection 2014.

Abstract

The Newcastle/Moore and El Reno tornadoes of May 2013 are recent reminders of the destructive power of tornadoes. A direct estimate of a tornado's power is difficult and dangerous to get. An indirect estimate on a categorical scale is available from a post-storm survery of the damage. Wind speed bounds are attached to the scale, but the scale is not adequate for analyzing trends in tornado intensity separate from trends in tornado frequency. Here tornado intensity on a continuum is estimated from damage path length and width, which are measured on continuous scales and correlated to the EF rating. The wind speeds on the EF scale are treated as interval censored data and regressed onto the path dimensions and fatalities. The regression model indicates a 25% increase in expected intensity over a threshold intensity of 29 m s(-1) for a 100 km increase in path length and a 17% increase in expected intensity for a one km increase in path width. The model shows a 43% increase in the expected intensity when fatalities are observed controlling for path dimensions. The estimated wind speeds correlate at a level of .77 (.34, .93) [95% confidence interval] with a small sample of wind speeds estimated independently from a doppler radar calibration. The estimated wind speeds allow analyses to be done on the tornado database that are not possible with the categorical scale. The modeled intensities can be used in climatology and in environmental and engineering applications. Research is needed to understand the upward trends in path length and width.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Disasters*
  • Models, Theoretical*
  • Tornadoes*

Grants and funding

Partial support for this work came from the Department of Geography at Florida State University and from Climatek, Inc. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.