MELISSA BLOCK, HOST:
Joining us now is NPR science correspondent Jon Hamilton who has done a lot of reporting on tornadoes before. And, Jon, talk a bit about the path of this tornado and the destruction that it's brought.
JON HAMILTON, BYLINE: Well, if you look at it on the weather maps, it looks like it cut a large swath that went a few miles south of Oklahoma City, so that would have taken it right through Moore. And that's a suburban - a number of suburban communities, lot of houses, lot of schools. This tornado was on the ground for 40 minutes, which gives it a lot of time to cause damage.
BLOCK: And the strength, the intensity of this tornado, what have you been hearing?
HAMILTON: It's a little hard to tell because most of the reports are preliminary, but people are saying it's at least to four or five. And judging from the pictures with the devastation that was clear, that would put it in that category. Now, a four or a five on the tornado scale would talk about winds of 166 to 200 miles an hour, maybe more. And when you get winds of 200 miles an hour, there's very little left after it passes by.
BLOCK: Yeah. And the images that we're seeing from television are just horrifying. I mean, they show entire neighborhoods in Moore than are flattened. This follows, Jon, a string of very destructive tornadoes yesterday as well in this area. And did people have warnings that these were coming?
HAMILTON: Yeah. Of course, usually, tornadoes occur in groups like this, and so yesterday, the conditions were favorable, so, too, today and, as I understand it, tomorrow as well. And yes, people had warning. For one thing, we're talking about the time of year and the place in the country where you most expect to see tornado. So if anybody is aware of the danger, it's people living in these areas.
And they had been told for many hours before the - these particular tornadoes spun up that the conditions were right for something happening. And as I understand it, when the tornadoes did form and touched down, there was at least 15 minutes of warning the people in the path, so people at least had time to get to some place low and a little safer.
BLOCK: What are the conditions that lead to tornadoes like this, Jon?
HAMILTON: Well, basically, you have a cold air coming down from the north and the west and storms, you know, thunderstorm systems moving along, and it needs warm air coming up from the Gulf. And it's the collision of those two that causes tornadoes to spin up and create this kind of devastation. And it happens in that place along Tornado Alley, most likely, that sort of a line where this tends to occur.
BLOCK: And there are warnings, Jon, still from the National Weather Service, of other tornadoes that could still hit this area?
HAMILTON: That's correct. As I understand it, there are warnings - they're expecting more tornadoes throughout this evening and a number more tomorrow when the conditions will still be very, very favorable for more tornadoes spinning up.
BLOCK: OK. Jon, thank you very much.
HAMILTON: You're welcome.
BLOCK: That's NPR's Jon Hamilton.
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ROBERT SIEGEL, HOST:
And again, here's what we know so far about the powerful tornado that hit Moore, Oklahoma. According to a spokesperson for the Oklahoma State Medical Examiner's Office, 51 people have died. That's a number that's been confirmed. And, of course, it may rise as more rescue efforts continue throughout the night. We will continue to cover this story on NPR, and we shall do that throughout tonight's newscast and, of course, tomorrow on NPR's MORNING EDITION. You're listening to ALL THINGS CONSIDERED from NPR News. Transcript provided by NPR, Copyright NPR.