00:00Well, in the forecast feed here as we ramp up through the weekend, Juneteenth weekend,
00:04we're concerned about severe weather again returning to the Plains.
00:07The brief break may have been nice, but it's not lasting long.
00:10Let's take a look at what we're up against Saturday.
00:12This is kind of a late bloomer Saturday afternoon, evening, and into Saturday night.
00:16We're looking at some aggressive storms that will fire off here in parts of Nebraska,
00:20and they'll be southeastbound tumbling into parts of Kansas.
00:24We've been looking at that area around Lawrence and Manhattan, Kansas here along Interstate 70
00:29at maybe close to midnight.
00:31We may be dealing with some nasty storms Saturday late evening and night
00:34with, again, some large hail and damaging winds.
00:37There's also going to be a risk for isolated tornadoes, also flash flooding.
00:41I don't want to neglect the flash flood risk here.
00:43We bump that up to a medium risk as well for this stretch here from eastern Colorado into western Missouri.
00:49Let's take a look at the details.
00:50I'm going to go back and forth between our graphics to the models for Saturday.
00:56Then we're going to go back to the graphics and then to the models for Sunday,
00:59and we'll look at, again, a quick look at our graphics for early parts of next week.
01:03So here we are.
01:04The driving factor behind this, it's a weak disturbance.
01:08There's not much to it, but it's enough.
01:09And I'm looking at the vorticity here, this little dip in the jet stream here,
01:14and you can kind of trace it.
01:16It's negatively tilted.
01:17It's not a very deep trough, but it's negatively tilted.
01:19Here's another depiction of it here in the NAM, connecting the dots here between the low point and the trough
01:26here.
01:26And you can see, especially late Saturday night, there's the orientation of the trough.
01:32So it slopes down and to the right.
01:34That's a slightly more aggressive format for a trough,
01:38and that tends to produce a little bit more sharp lift in the atmosphere.
01:41So, again, it's not a strong setup, but it's one that will bring us some strong lift in the atmosphere,
01:48given the warmth and the humidity in place.
01:51Here is the dew point map and the low-level flow as well.
01:55The surface streamlines, 2-meter streamlines, 6 feet up into the sky.
01:59So basically just around head level here.
02:01And you'll notice I'm going to highlight this sea green to dark green transition.
02:05That's the 70-degree dew point line.
02:09So that's really humid air that makes it sway all the way up to I-70,
02:13into that area around Manhattan, Kansas, Topeka, Lawrence, Kansas City, Jefferson City.
02:18And that's going to be really significant moisture to fuel these storms.
02:23And as we take a look at the energy helicity index,
02:26this is looking at a combination of a few different variables here in the atmosphere,
02:30but lift from Cape, and then also the spin that we talk about here,
02:36almost like a football spiraling through the air, that helicity value.
02:41If you get strong lift into an area with strong helicity,
02:44you'll begin to tilt an area of rotation upwards in the vertical,
02:49and that can lead to tornadoes.
02:50You'll notice that in Kansas, the tornado threat is going to be a little greater
02:53south of the main cluster of strong wind.
02:57So again, there's going to be a lot of thunderstorm activity that kind of rolls in this fashion.
03:02And it's the southeastern and southwestern storms that will have the best chance for tornado production.
03:08So back to our graphic here.
03:09We have some concerns, obviously, about Saturday afternoon, evening, and night
03:13with the severe weather hazards there.
03:17Let's take a look at this dip in the jet stream, the one that follows that first one.
03:22And I'm going to plot it here.
03:24This is going to be the driver for our Sunday severe weather.
03:27So we have to wait for it, but once this disturbance gets to the east of the Rockies,
03:33it begins to get a little more amplified.
03:35It's not a terribly deep, like a full latitude trough that we might see in March,
03:40but it's one that again has a negative tilt.
03:44I'm talking about this type of northwest to southeast.
03:48Remember y equals mx plus b?
03:50Remember that from high school math class?
03:54Positive tilt would be bottom left to top right.
03:57It's kind of like it's trending up and out as you go farther to the right.
04:00In this case, it's trending, if this were plotted on an x and y axis, down and to the right.
04:06That's the orientation of the trough.
04:08And that's what we talk about as a negatively tilted trough.
04:11That leads to more lift in the atmosphere.
04:14So the dip in the jet stream here, it's not terribly deep, but it's a moderately strong one.
04:21We have moderate amounts of warmth, but I'm going to show you the dew points here for Sunday.
04:25We're going to go high for the moisture content.
04:28And you look at all these parameters, and that lands us with a medium risk for severe weather on Sunday.
04:34So I'm going to go to the models, and I'm going to bring you back to the graphics.
04:37So the thing I wanted to hone in on on Sunday, just tremendous amounts of moisture.
04:41That 70-degree dew point line, Sunday, late afternoon, early evening.
04:45Here it is.
04:46It's again near I-70, all the way up into parts of southern Indiana.
04:50That's with the GFS model.
04:52Let's take a look at it with the NAMM.
04:54The NAMM's even juicier.
04:55Look at this.
04:55There's the 75-degree dew point line in that deep blue up into areas near Quincy, Illinois.
05:01And the 70-degree line up well to the north of Indianapolis and knifing east into areas around Xenia, Ohio.
05:07And here's the URP that's maybe not as aggressive with the 75-plus-degree dew point, but it's still very
05:14juicy out there.
05:14So when we take a look at this forecast for Sunday, there's our dip in the jet stream.
05:20We traced that with our forecast graphics.
05:23Looking at this guy here.
05:24That's what we kind of traced with our bubble.
05:26And when we come to that energy helicity index, again, the strongest instability is going to be south of I
05:33-70.
05:34There will be potential in the NAMM.
05:36The NAMM, again, has that more aggressive push farther north up into central Illinois.
05:40Again, there is some potential.
05:42There are some tornado parameters that do suggest Illinois, again, firmly in this conversation again.
05:48But it's not a slam dunk.
05:50The GFS says, no, it's farther south.
05:51So how are we playing it here with our forecast at AccuWeather?
05:55Well, as we go to the Sunday, Sunday evening forecast, we're hedging our bets a little more south compared to
06:03where most of the Illinois severe weather outbreaks have been so far this year.
06:06A lot of them have been up in central and north-central Illinois.
06:09This time, we're going a little farther south.
06:11We're kind of hedging toward southern Kansas, northern parts of Oklahoma, through the Ozark Plateau, down into the area around
06:17the Bootheel.
06:18And there will be some concern about some tornadoes down in this area here.
06:23We've got to keep a close eye on this here, Sunday and Sunday evening, then into the lower Ohio Valley.
06:27That front, then, does push farther southeast.
06:29So here's our forecast for Monday.
06:32And there's some discrepancy here.
06:34The GFS is farther south regarding the northeast.
06:37There are other models that take it farther north that might open the door for the yellow zone to come
06:41a little farther north.
06:42So we'll keep an eye on that.
06:43But overall, again, that is our forecast feed.
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