Improving tornado intensity estimates using operational Doppler weather radar

In the United States, the record of tornado occurrence and intensity is derived from a collection of eyewitness reports and post-event damage evaluations. Estimates of tornadic wind speeds based on this information can be misleading due to inconsistencies in building code compliance or regulations, varying reporting procedures, eyewitness biases, as well as the general lack of damageable structures. An alternative method of estimating ground-level tornado winds is demonstrated here using data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network. The method is based on a linear regression model that relates WSR-88D velocity measurements to the “true” tornado wind speeds at low levels, as given by measurements made by Doppler on Wheels (DOW) radars; the regression model is applicable once a tornado has been confirmed. The theoretical effectiveness of this method in sampling the wind field of an idealized vortex is evaluated using a simplified model that takes into consideration many of the inherent radar sampling limitations. The suggestion from this work (and from recent/ongoing studies by others) is that the WSR-88D can be used in isolation to estimate low-level tornado intensity.