Skip to main content

Breaking Down the March Tornado Outbreak

A map of areas with high rotational velocity, an important ingredient for forming tornadoes.
A map of areas with high rotational velocity, an important ingredient for forming tornadoes. (Image credit: NOAA/NSSL)

New images from the nation's Storm Prediction Center show how much of the South and Midwest were affected by the severe weather and tornadoes on Friday (March 2).

An entire month's worth of tornadoes struck across parts of the country from March 2 into the morning of March 3. The Storm Prediction Center received 81 reports of tornadoes on March 2, according to data filtered to remove duplicate reports of tornadoes. For the entire month of March, the 10-year average number of tornadoes is 87, according to the Weather Channel's severe weather expert Greg Forbes. The National Weather Service's storm survey teams have not yet confirmed the tornado reports, so these numbers could change. But if the numbers hold, the outbreak could go down as the largest single-day outbreak in March history.

In 2006, the biggest March outbreak saw 105 tornadoes from March 9 to 13. March 12 of that outbreak saw 62 confirmed tornadoes. Yesterday's outbreak could top that total.

(Image credit: SPC.)

The unfiltered storm reports in one new image show that the Storm Prediction Center received 128 tornado reports on March 2.

To see how the March 2 outbreak compared with the April 27, 2011, outbreak — the largest tornado outbreak in recorded history — meteorologists at the Storm Prediction Center compared the tornado and severe weather warnings issued during those outbreaks (image below). On the March 2 outbreak, the area of warning covered nearly 500,000 square miles (1.3 million square kilometers).

(Image credit: SPC)

During the April 27 outbreak, the area of warning covered more than 1 million square miles (2.6 million square km).The National Oceanic and Atmospheric Administration created a map of areas with high rotational velocity — an important ingredient for forming tornadoes — using data from NOAA's network of NEXRAD radar installations, processed by the National Severe Storms Laboratory in Norman, Okla. By examining these images, forecasters can determine the approximate tracks of so-called supercells, which feature strong rotation and are known for producing tornadoes. Some of these supercells had rotational velocity up to 180 mph (290 kph), and so their signature stands out from the surrounding storm areas. Features such as these are watched carefully for possible tornado outbreaks.

NPP VIIRS image of the March 2, 2012 Midwest Tornados (Image credit: NOAA)

An from NOAA's Suomi NPP VIIRS instrument shows the overshooting cloud tops and intense storms associated with March 2 tornado outbreak. The imagery was acquired over Illinois, Indiana, Ohio and Kentucky. Polar-orbiting satellites track the subtle changes in the environment that can trigger potentially deadly weather conditions, from tornadoes to tropical storms. Current operational POES data was critical for issuing watches and advisories days in advance of this outbreak.

You can follow OurAmazingPlanet staff writer Brett Israel on Twitter: @btisrael. Follow OurAmazingPlanet for the latest in Earth science and exploration news on Twitter @OAPlanet and on Facebook.

Brett Israel was a staff writer for Live Science with a focus on environmental issues. He holds a bachelor’s degree in biochemistry and molecular biology from The University of Georgia, a master’s degree in journalism from New York University, and has studied doctorate-level biochemistry at Emory University.