Tornado Safety for Tornado Alley and the Southeast

Tornadoes can happen in any month and in all 50 states. Still, the season moves north over the year, and the peak where you live depends on your region. The figures below come from the NSSL and the Storm Prediction Center (SPC).

NSSL says most tornadoes happen between 4 and 9 p.m. Some regions break that pattern. An NSSL-led research summary says Southeast tornadoes happen "much more frequently at night and in the cool season" than Plains tornadoes do. A 2021 study by researchers at the University of Oklahoma and the SPC found that people are least confident they would get a tornado warning between midnight and 4 a.m. It also found that the Southeast has the most tornadoes in that window, and the largest share of its tornadoes fall there. The same paper notes that nighttime tornadoes are more than twice as likely to kill as daytime ones, citing earlier research, and that the Southeast has a larger mobile home population.

Southeast storms are also harder to see coming. Hills and dense trees block the view, rain often hides the tornado, and many arrive in the dark. The SPC says warning signs at night include bright blue-green or white flashes near the ground (power lines snapping) and a loud, continuous roar.

⚠ In the Southeast, plan for a tornado that comes while you are asleep. Before you go to bed on any night with a severe weather risk, make sure something loud will wake you, such as a NOAA Weather Radio with a battery backup or a phone with emergency alerts turned on.

You usually get days of notice that a dangerous pattern is coming. The SPC issues convective outlooks for Days 1 through 8, and the Day 1 to 3 outlooks put each area into a risk category.

The US has rated tornadoes on the EF scale since 2007 (the SPC lists 1 February 2007 as the start date). Nobody measures the wind inside a tornado. Survey teams look at the damage afterward, match it against 28 types of structures and trees, and estimate the wind that would cause it. That is why a rating often comes out a day or more after the storm.

The SPC says most tornadoes are far weaker than the worst ones, EF5s are very rare, and even in violent tornadoes the survival rate is at least 99 percent. Most of the roughly 60 tornado deaths in an average year come from flying or falling debris, so protecting your head matters in any tornado.

⚠ Mobile and manufactured homes are not safe in a tornado, even when they are tied down. The SPC says most tornado deaths happen in mobile homes. Before storm season, pick a sturdy building you can reach in a few minutes, such as a community shelter, a church or a relative's house, and leave for it when a watch is issued or when the forecast calls for overnight storms. Do not wait for the warning.

Outdoors: get inside a sturdy building right away. Sheds and storage buildings will not protect you (NWS).

FEMA defines a safe room as a storm shelter built to its design criteria in FEMA P-361, giving what FEMA calls "near-absolute protection" in extreme winds. FEMA P-320 is the guide for homeowners, with building plans for a safe room on your property. Both draw on ICC 500, the national storm shelter standard. An NWS Louisville brochure on FEMA guidelines says safe rooms are tested against a 250 mph 3-second gust, and their walls and ceiling must stop a 15-pound two-by-four fired at 100 mph. FEMA describes a garage safe room in Joplin, Missouri, whose occupants were unharmed even though the 2011 EF5 tornado destroyed the house around it.

FEMA grant money for safe rooms goes through states and then local governments. If your state is not listed above, ask your state or county emergency management agency what is available. FEMA's Safe Room Helpline is 866-927-2104 (Saferoom@fema.dhs.gov).

⚠ Outdoor sirens are for people outside. The SPC says "outdoor sirens are for outdoor use," and Sedgwick County, Kansas says its sirens are "not meant to be heard indoors." Wind, rain, a running TV and a closed house can drown them out. Have at least two other ways to get a warning, and at least one that will wake you.