LAURA SULLIVAN, host: Back now to our top story, Hurricane Irene, which is clobbering the mid-Atlantic Coast with bands of rain reaching all the way from North Carolina to Maine. It's not all that powerful, as hurricanes go, but it is big. And it's moving through vulnerable, heavily populated areas. NPR science correspondent Joe Palca has been tracking the storm for us. And he's here with me in the studio. Joe, where is Irene now?
JOE PALCA: Well, it's about - it's on the border between North Carolina and Virginia, probably about 30 miles south-southeast of Norfolk. And it's also about 300 miles south-southwest of New York City. Its maximum winds are - sustained winds, anyway - are now 80 miles per hour, which is a little bit less than they were earlier but still, rather powerful. And it's heading north at about 13 miles an hour.
SULLIVAN: What is it that makes this such a dangerous storm? Is it the wind, the rain, the size?
PALCA: Well, take your pick. It's moving over - as you said, it's moving over a heavily populated area and really, that makes the difference. You know, one of these storms comes ashore in a desolate area, we wouldn't be talking about it. But here, it's a big deal. Then, as you said, it's huge. I mean, the hurricane-force winds extend out 80 miles. So that makes a 160-mile swath of destruction going through.
But there are also these - what they call tropical-force winds, which are still substantial - in the 30s and 40s miles-per-hour. And they're extending out for almost 600 miles now.
SULLIVAN: Six hundred miles.
PALCA: Yeah. It's just - it's a very, very large storm. And what happens is, you get those winds blowing into an area like - here in Washington, D.C., for example. Lot of trees; trees get knocked over. Not only do they fall on houses, which is bad, but they fall on power lines and disconnect power. There's millions - almost a million customers now, that I've seen, in Virginia that seem to be without power. So it's bad.
And the rain, by the way - we don't want to forget the rain - they've been talking about having up to 20 inches of rain in some places. So flash-flood warnings all over the place. It's really going to be hazardous.
SULLIVAN: Well, what happens when a storm this big hits a city with a lot of tall buildings, like New York City?
PALCA: Well, that's kind of interesting. We've been talking about the wind speed - you know, 80 miles an hour. That's measured at the ground. And as you go up in height, the wind can go up dramatically. So a lot of times, what you see in cities that are hit by hurricanes, is the top floors are the ones where the windows are blown out. And then what happens is, you get the delightful effect of flying glass coming down onto the city below. So it's not good to be out when this thing is really blowing.
SULLIVAN: So where do we go from here?
PALCA: Well, up the coast, you know, it will pick up speed as it passes New York. And they've extended the warnings - or at least, some of the tropical storm warnings - up into Canada. So this is going to be going up into Canada and still could - causing quite a bit of damage and consternation, I should think, over the next 24 to 48 hours.
SULLIVAN: That's NPR science correspondent Joe Palca. Joe, thanks so much.
PALCA: You're welcome.
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