Unbeknownst to you, an F5 tornado -- the kind that can obliterate a house in a heartbeat -- is barreling directly toward yours: Would you prefer 60 seconds warning or 20 minutes?

Silly question, you say? Yet research by a pair of Texas economists suggests that your choice may not matter in survival terms (that you’d have 19 minutes more to worry with option two is indisputable). In fact, the study raises the question of whether that extra time might actually do more harm than good.

But they’re economists.

More surprisingly, the chief technology officer for the country’s most extensive severe-weather-warning network says he would "bet there is some truth to their study" -- up to a point, and with funnel cloud-sized caveats that we’ll get to in a moment.

The discussion began recently with this headline -- "Early Tornado Warnings Not Always Helpful" -- that appeared on the Web site LiveScience: "The researchers analyzed data from more than 18,000 tornadoes in the United States between 1986 and 2002. Overall, they found that early warning is very helpful: On average it reduced expected injuries by about 32%.

"But when the researchers examined data from the most severe cases — the 300 out of 18,000 tornadoes in which people died — the effects of advanced warning were less clear. Overall, when people were notified of a tornado up to about 15 minutes ahead of time, deaths decreased. However, lead times greater than 15 minutes seemed to increase fatalities compared with no warning."

What could possibly account for such a counterintuitive outcome? The researchers acknowledge that their data is insufficient for firm conclusions, but here’s what they suspect: Given more time, people do dumb things like get in their car to try to outrun a tornado.

Being from Massachusetts, where tornadoes are rare, I can claim little firsthand knowledge of such situations. But I know a guy who knows: Chris Sloop, CTO at Weatherbug, which operates a network of more than 8,000 tracking stations and 1,000 cameras in schools, public-safety buildings and TV stations. Here’s some of what Sloop had to say about the economists’ research in our e-mail exchange:

"I bet there is some truth to their study," Sloop says. "When people don’t know what to do in a dangerous situation, many times they do the wrong thing. . . . I am surprised the authors didn’t take that approach. It is almost like they are saying that advance warning is a bad thing, when in reality it is a great thing; it’s just that people are not well educated enough to know how to respond. Of course, in cases like the most severe tornados, there may not be much you can even do that will save your life."