With over 1,000 happening each year, the U.S. has the strongest, most violent and most frequent tornado occurrences in the world. While they’re more prevalent in certain regions of the country, there is no state which has not been touched by a tornado, so it’s important for everyone to learn not only how tornadoes form, but what to do to prepare and protect yourself throughout tornado season and beyond.
A tornado begins when warm, moist air collides with cold, dry air. Initially, the colder air is pushed above the warmer air, but as that warmer air rises, it creates a horizontal rotation — think of a log that’s spinning in place on the water. This motion feeds itself, pulling in more warm air and accelerating the speed of the rotation. In some instances, the rising warm air will tilt that rolling air column until it forms a vertical vortex. It’s the moisture in the warmer air that creates the visible rotating cloud that’s the familiar tornado shape.
Although tornadoes can occur anywhere that warm, moist air collides with cold, dry air, in the U.S., this happens far more frequently in the areas of the country that are designated as Tornado Alley and Dixie Alley. While the boundaries of Tornado Alley are loosely defined, it’s generally considered the region in the middle of the U.S. that extends from Texas up through South Dakota. Dixie Alley, on the other hand, comprises the states running along the northern coast of the Gulf of Mexico. While Tornado Alley has more tornadoes, the ones in Dixie Alley tend to be more destructive.
While a tornado can form at any time of year when the conditions are right, most occur from spring through summer. Tornadoes in Dixie Alley tend to occur early in the season, while tornadoes in the northern region of Tornado Alley occur later in the season. This is because tornado activity is often located around the jet streams, fast-moving currents of air that always travel from west to east and form the dividing line between cold air from the north and hot air from the south (in the northern hemisphere). From early spring to late summer, the location of the jet stream that crosses the U.S. changes, which is why the likelihood of tornadoes also increases or decreases in certain areas throughout tornado season.
On February 1, 2007, the Enhanced Fujita Scale or EF Scale became the official way to rate how weak or strong a tornado is. There are six levels ranging from EF0 to EF5, with EF0 being the weakest (65-85 mph) and EF5 being the strongest (over 200 mph). It’s important to understand that the EF Scale is an estimate of wind speed that’s based on the damage that occurs, it’s not an actual measurement.
When the National Weather Service issues a Tornado Watch, it means that atmospheric conditions are favorable and the agency is watching for an occurrence. A Tornado Warning, on the other hand, means a tornado is occurring or is expected to develop and action must be taken immediately.
When a tornado is imminent, there are a few telltale signs that can give you a heads-up. A dark, greenish-colored sky with black storm clouds as well as large hail and a decrease in wind activity can be warning signs of a tornado. Descending funnel-shaped clouds and a roar like an approaching freight train are also clear signs that you’re in a danger zone. A swirling cloud of debris with no visible funnel can also be evidence of an approaching tornado.
Tornado activity can range from remaining stationary to traveling at up to 60 mph and last from an instant to several hours. The average tornado touches down for five minutes and travels at 10-20 mph. The most dangerous aspect of a tornado is the powerful updraft, which is strong enough to lift vehicles and dwellings from the ground and pull them to great heights in the air. Flying debris, however, is responsible for the most injuries and deaths during a tornado. After a tornado has passed, hazards range from stepping on a nail and objects falling to risks of fire, electrocution and explosions.
Surviving a tornado depends on planning, preparation and action. The following tips can help with planning and preparation, but only you can act.
The meteorologists at the National Oceanic and Atmospheric Administration issue daily forecasts for organized severe thunderstorms and closely monitor the areas that appear to be at a higher risk for tornadoes. Listening to a NOAA weather radio can keep you updated on changing weather conditions in your area so you know when you need to act. Additionally, be aware of any of the weather conditions listed in the preceding "Warning signs that a tornado is approaching" section of this article.
The first step you need to take to prepare for tornado season is to have a detailed family plan in place. This plan needs to cover discussing with your family what makes a safe shelter, which part of the home will be designated the safe room, what to do if you aren't together when a tornado touches down and more. The plan should also outline specific tasks for family members, such as who is responsible for the pets and who is responsible for gathering supplies because more hands make less work. Lastly, because hazards can remain after a tornado has passed, your plan also needs to include what to do after the tornado has passed.
Your emergency tornado kit should contain essential items in the following categories.
Food and water: A minimum of three days of food and water should be the top priority in your emergency tornado kit. This means three gallons of water for each family member and three days of nonperishable food such as protein bars, nuts, canned vegetables, breakfast cereal, multivitamins and more.
First aid, health and hygiene: Besides a comprehensive first aid kit, you should have at least a week's supply of medicine along with hearing aids, glasses, contact lenses or anything else you might need. Having an N95 respirator for each family member is highly recommended as well. Lastly, make sure you have a supply of items needed for personal hygiene such as soap, dental floss and hand sanitizer.
Communication, lighting and backup power: While it’s essential to have a cell phone with you in emergency situations, you should also consider an emergency radio to help you stay aware of the current conditions. It’s also helpful to have emergency lighting and several backup power sources to keep your devices running.
Important documents and papers: Keep all of your important papers such as financial documents, immunization records, identification documents, insurance policies and more stored in a fire- and water-resistant document bag. This becomes vital during emergencies.
Most of the damage caused by tornadoes is a result of wind and hail, which are likely already covered under your homeowner's insurance policy. However, flooding and other types of damage may not be covered. If you live in an area that has a higher rate of tornadoes, it’s advisable to sit down with your insurance agent to determine exactly what your policy covers in the event of a tornado touchdown.
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Allen Foster writes for BestReviews. BestReviews has helped millions of consumers simplify their purchasing decisions, saving them time and money.
