You're stuck in Minneapolis rush hour traffic on Interstate 94, near the Lowry Hill Tunnel. A thunderstorm spins out a tornado nearby. What can you do?
Not much. You're now among the most vulnerable people in a tornado. There are no good options.
Traffic's gridlocked, so you can't drive away. Hide under an overpass? It's a trap of swirling wind and debris. Hit the ditch immediately? That's what you were taught, but many experts believe that advice is more likely to get you hurt or killed.
In this situation, your best chance is to stop, stay in your car, duck below the dash -- and hope.
"When you have a big, vicious tornado moving across an area and traffic is just bumper to bumper -- that's probably one of the big scenarios that we really worry about," said Todd Krause, warning coordination meteorologist for the National Weather Service in Chanhassen.
"I don't know that there's really a safe way to be out there on the highway."
UNDER AN OVERPASS -- BAD IDEA
Unlike home, where you can run to the basement, or out shopping, where merchants probably have a plan to keep you safe, you're pretty much on your own in your car on the highway.
You might be lucky enough to be in front of an electronic highway sign that can send an immediate warning, or receive an alert on your smart phone that a tornado is near. But without a way to pinpoint the location, the information could lead to a fatal mistake.
"We have documented cases, especially in stronger tornadoes, of people trying to drive out of a tornado and being hit by tornadoes," said John Ferree, the National Weather Service official who oversees NWS weather warnings across the country. "Even if we put out a warning you would hear because you have the radio on ... sometimes the warning won't tell you enough to know if you're in it or not."
Some might go with their gut and hide beneath the nearest highway overpass -- a dangerously bad move since the wind can accelerate and concentrate the debris. In 1999 a huge tornado caught drivers exposed on I-35 in Moore, Okla. Drivers jammed the highway to park beneath an overpass, leaving their cars to take shelter underneath.
Of the dozen or so who tried to hide there, one was killed and others suffered horrific injuries -- "shattered bones, missing fingers, missing ears, missing noses, and being impaled by pieces of shingles," weather service researchers found.
The weather service had long warned of those dangers, but for decades also accepted that leaving the car immediately and heading to a ditch lower than the road was the safest move if a tornado was imminent.
Tom Schmidlin didn't buy that advice.
RETHINKING 'HIT THE DITCH'
A geography professor and meteorologist at Kent State University who studied killer tornadoes in the South in the 1990s, Schmidlin said he was struck by scenes he witnessed where mobile homes had been destroyed while cars and pickups sitting outside those homes sat upright.
"It became obvious to us pretty quickly that those people would have survived in their vehicle while they were killed in the mobile home," he said. "The mobile homes were flipped over and disintegrated, and the vehicles were still sitting upright."
In wind tunnel experiments, Schmidlin's researchers found vehicles more stable than had generally been presumed and "undoubtedly a safer place to be in a high wind than a mobile home."
That threw into question the long standing hit-the-ditch advice for mobile home owners -- and for people stuck on the highway.
A deep ditch might work, Schmidlin said. "But deep ditches are still out in the open. You're prone to lightning. The wind can still get you in a deep ditch. There's flying debris. You need to put as many layers between you and the wind as possible," he said. "Being in a car is at least one layer."
Schmidlin's work caught the attention of Richard Bissell, director of the Center for Emergency Education and Disaster Research at the University of Maryland Baltimore County, who was leading a review of Red Cross emergency response guidelines.
"The advice about abandoning your car and go lie in a low-lying area or ditch ... it didn't make any sense to us intrinsically," Bissell recalled. "Modern cars have a pretty good safety cage," and that's better than nothing if a tornado is on you.
NEW ADVICE: CONSIDER THE OPTIONS
Schmidlin's research led the weather service and Red Cross to overhaul the guidelines in 2009. Instead of hit-the-ditch, the advice is:
If you can't get to a shelter, you're in your car and flying debris hits, pull over, park and weigh these "last resort" options:
Stay in the car with the seat belt on. Put your head down below the windows, covering with your hands and a blanket if possible.
If you can safely get noticeably lower than the level of the roadway, exit your car and lie in that area, covering your head with your hands.
The advice also notes that your choice should be "driven by your specific circumstances," which begs the question: Are the signals on this still too mixed?
Despite the three-year-old guidelines, there is no "consistent message right now coming from either the meteorological community or the emergency preparedness community about exactly what you're supposed to do in every situation," said Kenneth Blumenfeld, a Twin Cities tornado researcher.
"We have not resolved the what-to-do-in-your-car argument yet. That is not a done deal," he said.
The old advice to get out of the car immediately can still be found on some weather service pages. Up until a month or two ago, the Federal Emergency Management Agency had the outdated advice posted on its site, Bissell said.
Though the weather service shifted its stance, Ferree cautions the updated advice isn't absolute.
"The problem is we have tornadoes every year that do kill people in vehicles," Ferree said.
He recalled a case last year where a tornado lifted a car off the ground and slammed it into a water tower a quarter mile away. It landed in a crushed ball.
"We don't want to tell everybody necessarily to get out of the car and get in a ditch, and we also don't want to tell everybody you should stay in your car and park your car and use the car," he said.
"Once you are in a car and in a situation where a tornado is bearing down, you don't have a lot of good choices," he said. "The choice between staying in the vehicle or getting out of the vehicle and into a ditch -- those are both bad choices. It's really tough to tell you what's the best way to go."
SHOULD HIGHWAYS BE CLOSED DURING TORNADOES?
Should emergency officials close highways and get people off the roads in tornado weather, the same way they shut down interstates during blizzards?
"It's perfectly feasible if time allows for the state patrol or local police to close the highways," said Schmidlin.
Officials could close the highways for 20 or 30 minutes as a dangerous storm approached and then passed.
"Logistically, that could be difficult," he said, but "if that saved two or three lives every year it might be worth the inconvenience if it was possible ... Nobody likes a traffic jam, but then nobody likes to drive into a tornado either."
Privately, public safety officials say that in a metro area with more highway lane miles per capita than Los Angeles, closing Twin Cities interstates during rush hour for fear of a tornado is impractical.
So, on a highway packed with cars beneath a thunderstorm that spawns a tornado, what's a driver to do?
"If you're in a car and there's no way to find a structure and it's imminent you're gonna be hit, I would stop the car," said Bissell.
"Leave the engine on -- because the air bags work while the engine's on -- and hunker down so that your head is below the level of the windowsill on the car because sometimes stuff blows through the windows. Leave your seat belts on. If the car does get picked up and blown around, you've received some protection by all that metal and the safety cage that's built around you."
It's not perfect, he added, but "better than being out in your sneakers and blue jeans ... which is about all you've got lying outside on your own."