00:00All right, who's ready for a taste of August heat and humidity?
00:04You better be ready because it's coming to the Midwest and into the Northeast as well.
00:12And anytime this time of year, you get the warmth and the humidity coming up,
00:17you know we're going to be dealing with thunderstorms and severe weather.
00:21I want to focus on the severe weather threat as we get into Sunday and Monday.
00:25There's going to be spotty severe weather Thursday afternoon, Friday.
00:30But I think those are the two days you have to keep an eye on.
00:33Now, I was talking about the heat and humidity.
00:35Let me take you to that.
00:37Let me do a little two shot here.
00:39Okay, this is Saturday morning, by the way.
00:41These are the two meter temperatures here.
00:44First of all, right off the bat, I mean in the morning, look how warm it is.
00:47Temperatures in the 60s and 70s.
00:49But watch what happens as we get into Saturday and Sunday here.
00:53There we go.
00:54That is roughly the temperatures, the high temperatures on Saturday.
00:59You've got this heat heading northward where you have 80-degree heat all the way up toward Des Moines,
01:04toward Kansas City, and of course back into the mid-south.
01:08But even Chicago, upper 70s to around 80 degrees, warmer than it certainly should be this time of the year.
01:14And not only that, take a look at the dew point temperatures here.
01:17Look how they're rising.
01:18Let me go back to Friday evening.
01:20Watch that surge of higher dew point air.
01:22I mean, this is Saturday afternoon, Saturday evening.
01:26This is 65 degrees or greater in here.
01:29This is a warm, steamy air mass that gets in the place beginning on Saturday.
01:36And then watch Sunday.
01:37Let me go back to the two-meter temperatures.
01:39So these are the low Saturday night.
01:41I mean, you have temperatures as lows in the middle 60s, right?
01:46Watch as we get into Sunday, that 80-degree mark all the way up in towards Chicago, near Indianapolis.
01:53This whole area is 80 degrees or better in here.
01:56And it's not only that.
01:58Look at the humidity, the dew point temperatures.
02:00This is a steamy, steamy air mass.
02:04Dew point temperature is in the middle to upper 60s in here.
02:07So it's warm and it's humid.
02:09So you have a heightened threat of thunderstorms.
02:12Now, what dictates the severe weather is the energy, right?
02:15We always talk about that, energy.
02:18And let me show you one other thing here.
02:20I want to show the instability here, what we call the CAPE, convective available potential energy.
02:27This is Saturday.
02:29You have a lot of instability in here.
02:31Look at these.
02:32You start talking about 2,000.
02:34This is joules per kilogram.
02:36We don't have to get into that.
02:37But this is telling you that you have a lot of instability, warm air at the surface, cooler air aloft,
02:46thunderstorms will pop.
02:47That's Saturday.
02:48Watch the area on Sunday right in here as well.
02:51So a lot of instability here.
02:53Now, just because you have the warmth and humidity and the instability doesn't mean you're going to get thunderstorms.
02:59You need energy.
02:59And we're going to measure that for you here.
03:01Let me show you the 500 millibar here as we get into Saturday.
03:05Now, what are we looking at here Saturday evening?
03:10On its surface, it doesn't look like a lot.
03:13You've got a trough here, and you've got these little weak impulses moving in the west-southwest flow.
03:19Now, keep in mind, though, we have a lot of instability and a lot of warmth and humidity.
03:23You don't need much.
03:24But it doesn't look like much on the 500 millibar, does it?
03:27The energy is back in the Rockies.
03:28But when you look at something else, the low-level jet, I talk about this all the time, watch the
03:32low-level jet go here.
03:34This is Saturday afternoon.
03:35Boom.
03:36Watch this.
03:37Boom.
03:38Right in here.
03:39Look how it increases in here.
03:41And we know we have the warmth and humidity.
03:43That tells me there's going to be some nasty thunderstorms here Saturday afternoon and Saturday evening.
03:49And when you look at the surface map, a couple of things you see here, you see what appears to
03:56be a lifting warm front in here, in here, right?
03:59You've got all this heat lifting warm fronts, and this would be in this area across Iowa and Missouri.
04:05I always get nervous just south of warm fronts because you know what you end up having just south of
04:10warm fronts?
04:11You have what I call directional wind shear that's changing the wind direction with height.
04:17This is what it looks like, right?
04:18If you're a parcel of air, let me go full screen on this so you can see a little better.
04:22If you're a parcel of air here in the low levels, you're first coming in from the east.
04:27Then you go to 3,000 feet, you're being pushed to the southeast.
04:31Then 6,000 feet out of the south.
04:33And then west-southwest winds in the middle and upper part of the atmosphere.
04:37What does this do?
04:38This creates the turning of wind with height.
04:42That causes the thunderstorms to rotate, and then that's how you can get tornadoes.
04:46So that's what I'm worried about here, not only Saturday, but Sunday as well.
04:51Let me show you the Saturday severe weather threat here.
04:56This is Saturday.
04:57Let me show it to you, and you'll notice that we have a little moderate risk within this area in
05:02Iowa.
05:03I bet you we're going to extend this a little more in Iowa.
05:06Isolated tornadoes hail.
05:08I still think damaging winds are the main threat, but I think there could be several tornadoes here on Saturday.
05:13Now, I think things ramp up on Sunday.
05:16I was talking about that we certainly have the instability, but I think you've got more energy on Sunday.
05:25Let me show you why.
05:26Let's go back to the 500 millibar.
05:29Let's go to the two-shot here.
05:31So, look at the energy here.
05:33This is Sunday.
05:35You've got a little more energy coming out in.
05:38See that?
05:39All in here.
05:40You start seeing more energy.
05:41I'm not saying it's a huge amount.
05:43I don't think we're looking at a tornado outbreak, but there's going to be enough energy in here.
05:46And look at the low-level jet.
05:48Let's watch that again.
05:50Watch this.
05:50Boom.
05:51Right there.
05:52Right in here.
05:54That's a lot of wind energy coming into a very unstable atmosphere here.
06:00And when you look at the surface map, what do you see on the modeling?
06:04Let's go to this here.
06:06You see, here we go, Sunday into Monday.
06:09Boom.
06:10Thunderstorms in there.
06:11So, I think you have a heightened threat of severe weather on Sunday.
06:16Let me show you the map here really quick.
06:20There we go.
06:21Right here.
06:22There's our severe weather threat on Sunday.
06:26If you get over a dozen tornadoes this weekend, I think Monday would be the day.
06:33Monday's the day.
06:34Not Sunday.
06:34I think there's some on Sunday.
06:35But Monday, let's keep an eye on that.
06:38Of the next seven days, I think Monday's the day that you really could be looking at quite a bit
06:45of severe weather.
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