AccuWeather's Jon Porter warns that 83 million Americans are under a severe weather threat as storms are expected to produce life-threatening and potentially historic flooding in the central U.S.
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00:00We're concerned AccuWeather experts, the flooding experts, are concerned about a historic and
00:04life-threatening flash flooding event that's going to be setting up here because we're going
00:08to have multiple rounds of heavy rainfall over the same areas. Ari, some places may get as much
00:15rainfall in five days as they might typically get in four months. That puts us into perspective of
00:21why we're so concerned. Absolutely. All right, what I guess is causing this and then if you
00:26can describe exactly what we're looking at here. Well this is the moisture that's in the atmosphere
00:31and moisture available in the atmosphere and when you're looking at these yellows and these
00:37red areas these are high levels of atmospheric moisture. Notice that as we put this loop into
00:42motion that is going to get continually focused here across the corridor from Arkansas over toward
00:47Tennessee and Kentucky for several days on end and look at where look at where the feed of moisture
00:53comes from. It's coming all the way down from the Caribbean. This is an atmospheric river.
00:58We often talk about those on the west coast, sometimes on the east coast, but this atmospheric
01:03river, a potent area of tropical moisture that's focused in the atmosphere, that's why it's called
01:08an atmospheric river, is going right up into the central part of the United States and it's coming
01:13from the Caribbean, a deep feed of tropical moisture. The other problem is that this big
01:19area of high pressure off the southeast coast is creating a traffic jam.
01:26So storm systems are not able to move fast through the central part of the United States. They'll
01:31continue to slow down and that's why we're going to be dealing with that persistent rain.
01:35You mentioned a day's worth of rain here in a short period of time and what we're looking at
01:40is the exclusive active rainfall forecast. It's a huge area that's at least going to get a couple
01:45inches of rain but really narrowing in on where we could see a foot or more. It's so unusual for
01:50us to have this type of rainfall forecast and not be talking about a tropical storm or hurricane.
01:56Of course there's a totally different situation but some areas here in that corridor from Arkansas
02:01to Kentucky and Tennessee who are used to dealing with the rain impacts from tropical rainstorms,
02:07this would be like getting two or three of those intense tropical rainstorms in the same week.
02:12Look at the amounts we're talking about here. 12 to 18 inches of rain in that heaviest corridor
02:18there with an AccuWeather local storm max of 21 inches which means that's the maximum conceivable
02:24rainfall amount that any location could receive and again that's why the amount of rain is such
02:29a concern but it's also going to be coming too fast too furious with rainfall rates sometimes
02:34two inches per hour or more and Ari when that falls over saturated ground that's when the risk
02:40of life-threatening flooding will ensue and we could be talking about a situation that goes from
02:44something that's dangerous to high water rising very rapidly and a true life-threatening emergency
02:50in the matter of a couple of minutes in these areas. That's why it's so important for people to
02:54move to higher ground if warnings are issued for your community. And you mentioned that kind of
02:59rainfall is what we typically see in tropical systems but so is a map like this often that we
03:05That's right we're talking about the risk for extreme impacts in that corridor from portions of
03:12Kentucky, Tennessee toward the Ozarks and again this is a great time to download the AccuWeather
03:17app and turn on push notifications. I also want to remind you if you know people that live in this
03:23area please give them a call and remind them you can help save people's lives by elevating their
03:28awareness of such an extreme weather event. This is the kind of thing where you might live in a
03:33community here for 30, 40 or 50 years and you would not have seen water in places that you will
03:40see it in some of these areas so a very unusual and dangerous setup. All right we appreciate your
03:45expertise AccuWeather chief meteorologist John Porter. Thank you for keeping us safe here and
03:49breaking it down.