AUDIE CORNISH, HOST:
A series of ominous factors are coming together to make Hurricane Florence a particularly worrisome storm. Meteorologist Bob Henson with Weather Underground has been following Florence. He joins us now to talk more. He's in Boulder, Colo. Welcome to the program.
BOB HENSON: Oh, thanks, Audie. Good to be here.
CORNISH: So to begin, I understand that the landfall factors for a storm are, like, wind, storm surge and rainfall. How does Florence look like it's shaping up in these categories that make it unusual?
HENSON: In this case, on all three of those - the storm surge, the heavy rains and high winds - Florence is pretty close to the top end on all three. So it really is a multipronged threat and a very serious one.
CORNISH: At what point did you and other meteorologists look at the indicators for Florence and think, this is actually strong in a way that is really not good for landfall?
HENSON: Well, Florence started to come together in terms of model projections a couple of days ago. And it was apparent it could be quite a strong hurricane on approach. Waters off the coast of the southeast are quite warm for this time of year. And what's become especially concerning is that it'll be approaching the coast pretty quickly through Thursday and Friday and then will really be slowing down once it gets inland. And that's the recipe that we saw, caused a lot of trouble during Hurricane Harvey in Texas. So it's very concerning to see this type of pattern appearing to set up with Florence.
CORNISH: Let's talk about another factor, the Carolinas themselves. Do these states have unique vulnerabilities that would make this storm, if it makes landfall, difficult going?
HENSON: There's certainly a lot of low-lying area in eastern North Carolina. And the coastal plain is pretty expansive - and a lot of low-lying territory there. There's been experience with major hurricane flooding. Hurricane Floyd in 1999 was pretty catastrophic in that part of the world. Now, South Carolina up through North Carolina - there was major flooding during Matthew in 2015. So we know that area is prone to flooding. And the amounts of rain projected from Florence, if it stalls out, is - it could approach some all-time records for any hurricane in that region.
CORNISH: You mentioned the problems that can arise because of the land being low-lying. I imagine that's also a problem when it comes to storm surge.
HENSON: Yes. The waters are fairly shallow offshore, which helps a hurricane to pile up the water and push it inland. So it's one of the more surge-prone parts of the Atlantic coast. And certainly, there's potential for some pretty damaging storm surge.
CORNISH: What are the optimistic scenarios here? Could Florence weaken before coming ashore?
HENSON: It's looking very unlikely that Florence will weaken any time before late Thursday. As it nears the coast, there will be a little bit more wind shear, and the shallower waters will affect it. So we could expect that it might drop to a Category 3 by the time it comes to shore. But by that point, the main impacts will pretty much be baked in because it will have been pushing water toward the coast for a couple of days. And there's just a lot of inertia in that water. And so the storm surge, which could be easily 6 to 12 feet in places - maybe a little bit more - that's going to strike even if Florence were to weaken suddenly.
If we're lucky Florence will move quickly once it hits shore. However, models are suggesting more that it will stall out and potentially even linger near the coast for a day or longer. And that will greatly exacerbate the rainfall threat. There's also going to be a lot of coastal erosion, especially toward the Outer Banks, it looks like. Multiple days of wind and heavy rain and surf will really take a beating on that area.
CORNISH: That's meteorologist Bob Henson with Weather Underground.
Thank you for speaking with us.
HENSON: My pleasure. Thanks. Transcript provided by NPR, Copyright NPR.