We discussed yesterday the pressure cooker situation of the atmosphere and how much potential energy there was. Refer back to the Skew-T charts I posted talking about the CAPE (which was over 3,000 J/kg). Yet, everything held off. Even what rolled over KC late in the evening was a far cry from what the atmosphere was capable of. Ah, then something happened.
Overnight, after about 1:30am, we finally saw the blow-up of t-storms across the area. Storms on the North end put down hail near ping pong ball size at times. Other locales picked up rain and in some isolated spots: a lot of it.
So what happened? The Low-Level Jet is what happened. We had the energy in place, we had enough juice in the atmosphere, and we had the lift needed. But the jet helped to feed warm, moist air into the area that was then pushed aloft and created the storms. The Low-Level Jet (or LLJ) is something that happens often in the central part of the country. It’s a small, but strong river of air that resides around the 850mb level, or about 5,000 feet up.
I cannot tell you have many times the LLJ was a key component in generating late night storms in Central Kansas. It was almost like clockwork during May & June.
Here are few charts that might give you a better idea. Both of these were from 7p last night (I was unable to find a decent, understandable upper air chart from 3am). These give a decent idea of what was going on.
I know, the charts can still be a little hard to read, especially that bottom one. Basically, the area I circled is Eastern KS and Western MO. The numbers given an indication of the amount of lift going on.
As I mentioned in one of the last updates I posted last night, it seems the RPM model from 6p was actually on to something the whole time! I will give it credit for doing a decent job of indicating storm development after 1am East of the Metro.
Turning our attention to Monday: we could see another round of severe weather in the area. The calendar may say July but the atmosphere plays by its own set of rules. Already the Storm Prediction Center out of Norman, Oklahoma is putting most of our coverage area in a Slight Risk:
Don’t be fooled by the term “slight”. There is a big debate within the weather world over the use of that word because the casual person doesn’t perceive that as meaning much. Then, when a monster storm tears up their town they don’t understand why because it was just supposed to be a “slight” risk.
The takeaway here: the area in yellow has a respectable chance of seeing thunderstorms develop. Of the storms that do get going, some will likely be strong to severe. Of the ones that DO reach severe criteria, winds over 60mph and hail the size of quarters to even golf balls is possible. Does this mean everyone will see that? NO. Not at all. But this is why it’s a “slight risk”…. there is a “slight risk” that anyone inside the yellow area could see a storm that produces hail and high winds. Also, a tornado or two cannot be ruled out. The problem here is that despite all of our technology and computers, we cannot tell you with great certainty where exactly a severe storm will occur. No meteorologist can. And if anyone SAYS to you they can, you better hang onto your wallet as well! This is why we use percentage chances. And when it comes to the SPC, they have a method to what they do. Here is a quick breakdown:
Slight Risk: Means there will be well-organized areas of severe weather, but in a relatively small coverage area. Storms would be on the lower side of severe, with hail mainly around quarter to golfball size and a tornado or two possible. Damaging wind gusts near 60mph are also possible.
Moderate Risk: Well-organized areas of severe weather over a larger coverage area and/or the storms that form may pose a more serious risk (such as hail near softball size or good indications of a tornado outbreak).
High Risk: Not used often, but when put into place it indicates a higher confidence of a significant severe weather outbreak featuring a multitude of severe components (very large hail; numerous large and/or long-lived tornadoes)
Here is a breakdown of how the SPC arrives at their terminology for Slight, Moderate, & High:
That’s just a basic crash course on how the SPC does what they do. You can see how they convert percentages to the various levels. There is talk this year of trying out some new words and changing things up a bit all in an effort to better inform the public.
As you can imagine, we’ll be tracking this all day Monday. And odds are things will likely change just a bit. I encourage you stay with us and be weather aware Monday afternoon. Now, I have to go give the forecast on air. See you in a few minutes.