Which Way Do Tornadoes Travel…Any Ideas?

ImageHave you ever wondered which way a tornado travels once it touches the ground? Which compass direction it tends to follow—are tornadoes random in their paths or do they follow directional patterns? Due to the literally brilliant work of data visualization expert John Nelson, we now have an answer. Using publicly available data from several sources, including the National Oceanic and Atmospheric Administration (NOAA) and the National Weather Service (NWS), he has produced visual “Tornado Travel Maps” that plot the historic proportion of tornadoes by the compass direction they have traveled, weighted by distance and intensity, during the past 63 years.

These  beautifully colorful maps are just the latest example of Nelson’s innovative work, which includes data-driven depictions of several major U.S. wildfires, more than 150 years of tropical storms and hurricanes and worldwide earthquakes covering more than a century. Similar to the tornado maps, Nelson pulls data from sources like NASA, NOAA and the U.S. Geological Survey. He then adds a creative, multi-colored visualization to the data summary to produce striking illustrations of natural disasters covering decades of activity.

“Not surprisingly,” says Nelson of the data, “the lion’s share of storms travel in a northeastern direction along with the prevailing winds (and carry F5 storms at double the rate as the other quadrants). I was interested in seeing just how great a proportion actually do. Beyond that, I was interested in seeing regional trends where historic storms have bucked that NE trend and traveled some other direction.”

Nelson’s data analysis uncovered other interesting tornado movement trends:

  • Tornadoes moving toward the northwest tend to cluster in the western Great Plains and along the Atlantic Coast, most likely associated with storms created by landfall hurricanes.
  • Tornadoes traveling toward the southeast most often occur in the northern plains states rather than in the South, which is an exception to the overall trend of all tornadoes.

According to the blog i09, these maps are part of a larger plan to improve upon current emergency response systems by dividing the country into tornado warning zones. New York-based meteorologist Robert Staskowski, who Nelson credits with coming up with the idea, says the tornado warning grid would be based on existing maps used by the NWS, but enhanced to include the primary angle of travel of the most powerful tornadoes, based on historical and current data, to strengthen safety and evacuation procedures.

The strategy is that by using these maps and other data, government and individuals are able to respond to devastating tornadoes and other natural disasters more effectively. Crawford helps manage the effects of tornadoes through its Catastrophe Services unit, the insurance industry’s leading independent adjusting resource for claims management in response to natural and man-made disasters, and also through its Global Technical Services business, which focuses on large and complex losses. Find out more about our range of catastrophe response services by clicking here.

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