When severe weather strikes in the United States, there are several ways individuals can ready themselves for the impacts of hail, rain, strong winds, and more. Tornadoes, in particular, present a significant threat, capable of causing widespread power outages, devastating property damage, and loss of life. The U.S. experiences approximately 1,200 tornadoes annually.
It is crucial, according to experts, to pay attention to forecasts and understand the different stages of weather alerts to stay safe. Here’s what you need to know about the causes of these storms and the various alerts that signal watches, warnings, and emergencies.
What factors contribute to tornado formation?
Tornadoes can form in the large areas of low atmospheric pressure that accompany some storm systems. These systems often bring stormy weather, and the intensity can be exacerbated by pressure levels. Low-pressure areas attract air, leading to the development of rain and wind.
“In the spring and during transitional seasons – spring, fall, and even winter – we experience strong, extratropical low-pressure systems,” explained Victor Gensini, an atmospheric sciences professor at Northern Illinois University. “These are storm systems that occur in each hemisphere’s mid-latitudes.”
“If you envision a map of the United States with a large ‘U’ drawn across it, that would represent a significant trough,” he added. “This trough encourages the formation of a low-pressure area and a robust storm system.”
How do storm systems transform into tornadoes?
Such storm systems generate intense winds and hail. When combined with a “warm sector” – referring to the section of the low-pressure storm system with warm, humid air rising – thunderstorms can form. Under the right conditions, which include warm, moist air near the ground, cooler dry air above, and shifting winds, these thunderstorms have the potential to birth tornadoes, as noted by the National Weather Service.
What distinguishes a tornado watch, warning, and emergency?
The Storm Prediction Center of the National Weather Service issues a tornado watch for an area, which can be up to ten hours before a storm when conditions signal the possibility of tornadoes. Residents in these locations, typically spanning several counties or states, should prepare for the chance of a possible warning.
A warning is issued by local forecast offices when radar indicates an imminent or already spotted tornado. This usually applies to a smaller region, such as a city or county. During a warning, people should take action, like moving to a shelter on the lowest floor of a building and steering clear of windows.
Tornado emergencies represent the weather service’s highest alert level and are declared when a tornado has touched down in an area, with confirmed catastrophic damage. Though rare, these situations necessitate immediate sheltering in place.
How should you prepare for tornadoes?
Experts recommend having multiple means to receive tornado watches and warnings and understanding what each term means. Weather radios are especially useful when power is out, and televisions and standard radios fail.
It’s also vital to have access to safe, enclosed, and underground shelters—or above-ground rooms designed to withstand tornado-level winds—prepared in advance.
