AccuWeather's Bernie Rayno warns of late-week storms that are expected to develop and hit the south-central U.S. with flooding, hail and tornadoes. The threat will continue to move eastward.
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00:00They look like bowling balls, don't they? The three storms. Here's one coming into California.
00:05We talked about that. Here's the second one. Here's the third one. They're all lined up.
00:09I'm going to track them. Now, this first storm is going to be coming into a very dry atmosphere
00:14across Texas in the Mid-South on Wednesday. So we're not looking at a whole lot of severe
00:18weather with. And you also notice that it weakens a little bit as it comes through.
00:22But you know what? There's enough energy that we're going to get some strong thunderstorms.
00:26They're just going to be spotty. This kind of sets the table for the next storm, because
00:30while there's dry air across Texas now, this will help moisten things up. Here comes the next storm.
00:36Now, what this storm is going to lack in moisture, it's going to make up with a lot of what I call
00:43dynamics, a lot of wind energy in the atmosphere here. I can see how the severe weather does not
00:51get as high as I'm afraid it could on Friday because of a limited amounts of Gulf moisture.
00:56I'm concerned that there's enough, given the dynamics of the situation. And what do I mean
01:01by that? First of all, the dip in the jet stream, this upper low is strengthening, number one. So
01:06you get more upward motion on its eastern side. It's also tilted from northwest to southeast,
01:12what I call a negative tilt. When you see that, that means all the energy is on the eastern side
01:16of the trough, where you do have the moisture and the warmth, so it intersects it. The other thing,
01:23note the wind direction on the eastern side. It's what I call a diffluent flow. What do I mean by
01:30that? What do I mean by that is that the air is spreading away, a lot, it's spreading out. And
01:36when you spread it out a lot, you bring it in at the surface. So that increases the amount
01:42of flow coming into the storm, which increases the upward motion, which can increase the intensity
01:48of the precipitation. The other thing that you see in a diffluent flow is what I call directional
01:54wind shear. That is a change with wind direction and height. Here's an example. More of the east
02:00than southeast from the surface to 3,000 feet, then more out of the south and then southwest.
02:06So if you're a parcel there and you're following the wind direction, you know what you're going to
02:09do? You're going to start to rotate. This supports rotation, which then supports thunderstorms that
02:16can produce tornadoes. That's the concern I have for Friday. It's a large area of a moderate risk,
02:22from Sioux Falls all the way down into northern parts of Louisiana. Now, there's going to be
02:26damaging winds with these thunderstorms. These are going to be very fast moving. We have an
02:30AccuWeather local storm at 100 miles per hour. But because of that changing wind direction with height,
02:36I'm afraid there's going to be tornadoes on the ground. I can easily see two dozen or more
02:41on the ground in this area. Now, everything shifts east. And by the way, these will be
02:46fast moving thunderstorms that will linger well past sunset, probably well past midnight.
02:52So severe weather at night is always dangerous. Now, the severe weather shifts to the east on
02:57Saturday, especially in the afternoon and night. We have a large moderate risk here from Louisville
03:01toward New Orleans. I think there's damaging winds and tornadoes on the ground. I don't have quite
03:06a feel yet on how many. Once I do, we'll certainly pass that along. These thunderstorms are going to
03:12be slower movers. So we have to introduce some other severe weather into the equation. That's
03:17flash flooding. I'm worried about that, especially Saturday, Saturday night. Look at that area from
03:23Nashville up toward Lexington, where we could be looking at multiple inches of rain that could
03:27produce flash flooding. Also, snow on the northern side of this storm. The central and southern
03:33Rockies Thursday night into Friday, then Friday night into Saturday across the upper Midwest.
03:37If we get a blizzard, I think it'll be in the eastern Dakotas and western Minnesota.