Weekend to begin with severe weather for Midwest and mid-Atlantic

AccuWeather

The Midwest and mid-Atlantic regions of the U.S. are at a significant risk of severe weather to start the early weekend with the threat of hail, flash flooding and tornadoes on Friday night, May 16.

Transcript

00:00Whenever we talk about severe weather, the one thing that we know about severe weather,

00:05the atmosphere never hides its intentions.

00:08It's like a bullhorn telling you where the general area is going to be, and the ingredients

00:13are always, always the same.

00:16Let's begin with ingredient number one, heat.

00:19And we've got unusual heat, and that's the biggest concern that we've got with this.

00:23Look at this, temperatures in the 80s and 90s across the south here.

00:28This type of heat is more reminiscent of mid-June or early July than it is mid-May.

00:35So we've got unusual heat and humidity just to the south.

00:39That warm, moist air is what's going to feed, it'll be the fuel for these severe thunderstorms.

00:44It's one of the reasons where unusual heat and humidity is why we're concerned about unusually

00:48high risk of damaging winds.

00:50And there's the humidity.

00:51Take a look at our future dew points.

00:52Listen, anything in green is above 60 degrees.

00:55That's the threshold.

00:56You can see some dark green showing up there, 65, 66 from Nashville all the way up into Kentucky.

01:02So we have the warmth.

01:04We have the humidity.

01:05It's unusually warm.

01:07And then think of this as the gasoline.

01:10Let's talk about the match, John.

01:12Yeah, here comes the match.

01:14And this is going to ignite the whole setup.

01:16We have a very potent jet stream disturbance that's going to be racing eastbound at about

01:2120,000 feet in the atmosphere.

01:22And that's going to create lift.

01:23So we've got the fuel in place.

01:26We talked about the warmth and the moisture.

01:28But then this is what ignites it all because it generates lift in the atmosphere to build those tall thunderstorm clouds.

01:35And, you know, you and I both studied at Penn State.

01:37One of our mentors, Dr. Michael Fridge, just an icon in the meteorology ranks.

01:43He always talked about the low-level jet.

01:44The winds are around 5,000 feet.

01:46Not only to diagnose where they're strongest, but are they increasing or decreasing?

01:51And when there's an increasing low-level jet, look out.

01:54Let's take a look at that product, John.

01:55What do you see?

01:56Well, when you and I were studying this this morning, Bernie, the thing that hit us about

02:00it is watch the increase in darker colors across this corridor as you loop this out through

02:05Friday afternoon.

02:06We have wind speeds above 100 and 105 miles per hour at 5,000 feet.

02:11And when you have such high winds at that level in the atmosphere, that's an indication of

02:16the damaging wind potential.

02:18And also, this can impart shear or wind shear or changing wind speed and direction with height

02:24in the atmosphere.

02:25That's the reason why we're concerned about a widely separated tornado risk as well.

02:30Now, we start off in the morning, some morning convection.

02:33Maybe they're wind, maybe they're hailers.

02:35But it's the late afternoon, John.

02:37And watch the cluster of thunderstorms start to develop here as early as 3 o'clock.

02:42What catches our eye about this is how quickly these erupt.

02:46And then they consolidate, Bernie, into clusters of thunderstorms.

02:50And when you get this type of signature here on a simulated, what the radar will look like

02:55this at 9 p.m. central, that's an indication that these storms can have a lot of damaging

02:59wind potential that can down trees, power lines, and lead to widespread power outages.

03:04And then watch how it consolidates through the evening.

03:07There's no rest on this one through the evening and into the overnight.

03:10It keeps hauling eastbound.

03:12A lot of times these clusters of storms can really race eastward and produce a damaging

03:17wind threat over a multi-state area.

03:20We're concerned this could even become a derecho, which is a particularly intense thunderstorm

03:26windstorm with widespread wind damages.

03:28It's the kind of power outages that in some cases could last for days in the hardest hit

03:32areas.

03:33John, really quickly here.

03:34Have we decided to make any changes with our severe weather threat?

03:38We just ended MEP discussion.

03:39Right.

03:40We have AccuWeather experts have a high risk here across parts of the Ohio Valley.

03:44We're the only known source to be talking about it in that way.

03:47The government and other sources do not have that level of high risk that AccuWeather meteorologists

03:51are concerned about.

03:52We think it could be a widespread damaging wind event, as mentioned.

03:55And we're going to be pulling this moderate risk a bit closer to Pittsburgh and also further

03:59south and east here across parts of Tennessee to account for that risk for damaging winds

04:04and widely separated tornadoes.

04:06We're worried about power outages.

04:08We're going to end on this map.

04:09Know what to do.

04:10If you have a downed power line, stay away from them and do get ready.

04:14We are very concerned about widespread power outages in Kentucky, Tennessee, and southern

04:20parts of Illinois and Indiana.

04:22Chief Meteorologist John Porter, thanks for joining us here on AccuWeather Early.

04:26Chief Meteorologist John Porter, thanks for joining us here on AccuWeather.

04:29Chief Meteorologist John Porter, thanks for joining us here on AccuWeather.

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