Study Finds Doppler Radars Save Lives

Doppler radars have been one of the biggest advances in meteorology during my 38 years as a meteorologist. So I my interest was really piqued by a study published in the June issue of Weather and Forecasting from the American Meteorological Society. That study finds that the Doppler radars in use by the National Weather Service since the early 1990s are saving nearly 80 lives a year that might otherwise be lost to tornadoes.

The relatively new radars allowed forecasters to issue warnings for 60 percent of tornadoes, up from 35 percent before the instruments were installed. The average lead times also rose over 4 minutes; lead time is the time between warning issuance and initial touchdown of a tornado.

The authors of the study, Kevin M. Simmons of Austin College in Sherman, Texas, and Daniel Sutter of the University of Oklahoma, looked at 14,979 tornadoes that struck in the United States between 1986 and 1999. Of those 7,900 occurred before the new radars were installed and 7,079 took place afterward. They rated the tornadoes by size, distance traveled, population density where they struck and other factors and compared the damage done before and after the modern radars were installed.

They concluded that 79 fatalities and 1,050 injuries per year have been avoided because of the Doppler radars.

National Weather Service Director during the development and implementation of the Doppler radar network, Elbert W. "Joe" Friday, said the finding "really does validate the modernization."
Dr. Friday, who was not part of the research team for this study, said, “The lifesaving makes all the effort worthwhile.”

The study noted that for all tornadoes, the percentage of tornadoes for which warnings were issued jumped from 35 percent to 59.7 percent.

More interesting was the finding that for the most powerful storms, F5 on the Fujita-scale, the warning rate went from 80 percent to 100 percent. The improvement was just as obvious for Category 4 twisters with a warning rate climbing from 64.2 percent to 93.5 percent.

Warning lead times also improved. For all tornadoes, the amount of warning lead time went from 5.3 minutes to 9.5 minutes. But for Category 5 storms it jumped from 11.7 minutes to 16.2 minutes, an improvement of almost 50 percent. For F4 tornadoes the warning time nearly doubled from 8.6 minutes to 15.0 minutes.

Doppler radars differ from older, conventional radars with their ability to measure how the air is moving in thunderstorms. The thunderstorms that produce tornadoes are filled with rain, hail, and often debris that these radars can detect and measure.

This study sure makes me feel good to be a meteorologist. Let's hope that future improvements such as phased-array radar will see this same kind of enhancement in warnings.

-Brian-