The National Weather Service released a sobering preliminary analysis of one of the deadly tornadoes that tore across southern Mississippi on Easter Sunday. Meteorologists who surveyed the damage left behind by the EF-4 tornado found that its path was “at least” two miles wide at one point. This tornado was the largest ever recorded in Mississippi, and this survey places it among the largest on record anywhere in the country.
The tornado outbreak on April 12 and April 13 produced more than 100 tornadoes from central Texas to central Maryland, which made this one of the most prolific outbreaks we’ve seen in the United States in several years. More than 30 people lost their lives in the storms.
Out of all the tornadoes that touched down during the outbreak, one storm in southern Mississippi on Sunday evening stood out for its size and intensity. Meteorologists issued a “tornado emergency” for communities in the path of the storm, warning that a large and destructive tornado was in progress and heading their way.
The intensity of the winds and debris on radar imagery quickly made it clear that this would be a devastating storm for anyone in its path. The radar showed an enormous amount of debris flying through the atmosphere many dozens of miles downwind from the storm itself, a hallmark of violent tornadoes.
The Storm Prediction Center (SPC) even issued a mesoscale discussion—a small-scale, short term forecast—alerting the region that radar and environmental data indicated that the tornado was likely an EF-4 or an EF-5. Meteorologists usually don’t put out that kind of a statement while a storm is in progress, but the SPC closed the discussion with a harrowing, all-caps warning: “THIS IS AN EXCEPTIONALLY RARE EVENT.”
Sunday’s two-mile-wide tornado was rare indeed. Only a handful of tornadoes on record have reached or exceeded a maximum width of two miles. Extra-wide tornadoes are often comprised of multiple smaller vortices rotating within a larger tornadic circulation.
The widest tornado on record touched down in El Reno, Oklahoma, on May 31, 2013. The tornado reached a maximum width of 2.6 miles as it passed just south of El Reno, which is about 30 minutes west of Oklahoma City. The storm grew so quickly that it killed several storm chasers and injured a Weather Channel crew after their SUV was blown off the road.
A preliminary damage survey conducted after Sunday’s storm found EF-4 damage on the Enhanced Fujita Scale, with an estimated peak wind speed somewhere between 170 and 200 MPH. Meteorologists arrive at a tornado’s maximum strength by surveying the damage they leave behind. Some meteorologists and storm chasers speculated on social media that Sunday’s tornado could receive a scale-topping EF-5 rating, but preliminary surveys have only found EF-4 damage. Some of the evidence cited for this EF-4 rating was the total destruction of a cinder block building, a church, and several well-built homes.
It’s very hard for meteorologists to find EF-5 damage, especially in sparsely populated areas where tornadoes don’t hit many structures. The devastation left by a high-end EF-4 is often total as there are few structures that withstand winds that climb over 200 MPH. Surveyors often have to resort to subtle clues—such as broken foundation bolts or concrete parking blocks tossed a great distance—in order to assign the highest rating to a tornado.
While large tornadoes tend to be strong, size doesn’t always determine strength. The only F5 tornado ever recorded in Canada struck Elie, Manitoba, on June 22, 2007, and it was only a few hundred yards wide at its largest point.