Here is an example of a sounding that I will be using to explain soundings to you all. It is from the Pilger EF4 tornado’s environment.

So let’s start with the Skew-T. That is the big box in the upper left. It is called that because it is skewed with height. You do not follow the temp numbers at the bottom straight up, you follow the light lines that go bottom left to top right. This is what it would look like if unskewed – it would be a bit less obvious of what a good lapse rate is.

There are 3 important lines to follow on a skew-t: the green line shows the Dew Point, the red line shows the Temperature, and the white dotted line is the temp of a parcel of air lifted adiabatically (when a gas is compressed under adiabatic conditions, its pressure increases and its temperature rises without the gain or loss of any heat.)

From this, you can learn a lot. CAPE is a measure of potential energy in the atmosphere, due to warm air rising, causing lift. This is a really good tornado sounding because it has lots of CAPE, and the CAPE is fat. The space between the temp line and the adiabatic temperature line is CAPE, because the parcel of air will always rise when it is warmer than the surrounding atmosphere. The skew-t is helpful for gauging tornado potential more than raw CAPE because 1000 CAPE distributed in a short and fat way is much better than 1000 CAPE tall and skinny.

Here is what I mean with the skinny VS fat CAPE. These both have around equal CAPE values (apparently, just eyeballing it doesn’t look like it but the point still remains), but the latter has the CAPE more concentrated, meaning the updraft can be stronger and faster.

Tornadoes often care way more about low-level parameters, though upper-level support is definitely necessary. A supercell won’t exist without it. But low-level parameters often make the tornado. Which brings me to the area with all the parameters, below the skew t. This is often located in different places but sharp.py soundings always have it in the bottom left. I cropped to just the ones directly related to skew ts. It tells you 4 different types of CAPE and CIN (I will talk about CIN later), along with other params below that. 3CAPE is a measure of CAPE in the low 3 km, and honestly, this sounding has very little. It is quite useful sometimes; 7/19 a surprising event (to the SPC at least) had I think 200. It is hella useful to make an eh event actually pretty good. The only other one in this part that I know what it is is DCAPE, which is CAPE for downdrafts, but I have never used it. Actually, some of the others are things like humidity but that’s more self-explanatory. PW or Precipitable water is the amount of water that is present in a column of air if it all precipitated.

Here is well-defined document that talks about DCAPE.

So let’s talk CIN/CINH, which stands for Convective Inhibition. It is also known as capping. This is an increase in temp (red line) in the lower levels that stops parcels of air from rising. It shows as a little bump in the red line shown in this sounding. CINH can sometimes ruin a perfectly good day and is often the culprit behind busts. You can’t just subtract CINH from CAPE or something like that, because parcels literally just won’t rise through it, if it is warmer than the parcel, it will not rise.

Now, lighter caps can be overcome, and in fact, you actually want capping in the morning. With surface heating, the parcel temp will rise, until the curve will stay warmer than the cap, and this will make it so that supercell development can be possible. Oftentimes caps over 100 CINH at 12z will be eroded by the afternoon. With the capping that existed earlier, the storms often initiate later, meaning the surface has more time to warm, and the updraft can be stronger. For the multiple types of CAPE, I’m pretty sure MUCAPE is for elevated storms, and ML and SB CAPE is for Surface-based storms. Elevated storms, btw, are storms where the parcel originates not from the surface. These storms can’t have tornadoes, but they can have hail and wind (and are often picturesque)

Wind shear is important to the development of a supercell. It tilts the updraft, so that the updraft and downdraft regions do not interfere, and help to get the storm rotating in the first place. The first is done through speed shear. This is increasing (or decreasing technically but you don’t want that) wind speed with height, which tilts the column of air. The second is achieved through directional shear, which is where the wind direction changes with height.
This tall column shows the wind speed with height. This is actually enough speed shear, even though it doesn’t increase much after a little bit.

Directional shear is a bit harder to explain. You can actually see it well in 2 places. In the column of wind barbs to the left of the wind speed chart, or the hodograph in the very upper left. I’ll be going over the hodograph. The red end shows the surface wind speed and direction, and the blue end shows it for the very upper atmosphere. The red portion is 0-3km, green is 3-6, yellow 6-9, and blue 9km+. Realistically 0-6 km is the most important part, so its a little hard to judge a good hodograph sometimes if you don’t pay less attention to yellow and blue. But what shows a good hodograph?

A good hodograph is characterized by a long, hook-shaped hodograph (like this one). You do not want a straight line hodograph or a weird shaped one. It shows turning of winds with height. Something to note is backing and veering. The more backed it is you’re moving counterclockwise and for veering its clockwise. When someone says “the surface winds are backed” that means that the surface winds are going towards the NW or even towards the W. That is very good, as you want your winds to veer as you get higher (for cyclonic storms), and when the surface winds start backed this is easier.

There is also something very important called Veer-Back-Veer (VBV) or just Veer-Back (VB). This is when at lower levels the environment veers, but then it backs as you get higher. This often creates messy storms that have crappy organization. The lower in the atmosphere the backing occurs the worse it can be, because of the lower atmosphere turning to be more important. Here is an example of veer-back, and it can mess with the storm. This thread has good info that goes deeper than I did with more detail, but it is also more complicated.

And in the middle bottom are the parameters for shear and such. These are a bit simpler if my explanation of hodographs wasn’t clear enough. SRH is a measure of turning with height, the higher the better. These values are quite good. SFC-1km around 100 and SFC-3km around 150 are minimums that you can look for generally. For 0-6km bulk shear, I usually look for around 50 knots or higher.

Often you get high CAPE low shear environments or vice versa. High CAPE can sometimes make up for low shear, especially with boundaries like outflow boundaries. High shear low CAPE is often more sketchy as shear can literally tear apart developing updrafts. This can actually be helpful in environments with better CAPE and high shear though because it will kill off all the weak updrafts to stop them from stealing energy from stronger ones. You need better CAPE if you have high shear. (A good parameter to look at for that is the Bulk Richardson’s Number.

Now say you are looking for a good sounding, and you find one like this with a beautiful hodo (ignore the garbage skew-t for this). Well, you can’t use this sounding for anything useful. Why? It is contaminated by convection. Modeled convection can ruin a sounding and make it completely and utterly useless for any info at all. How can you tell if it is contaminated? Well, 2 ways. Firstly, if the dew point is right up against the temp for much of the atmosphere, then it is most likely contaminated. And if the red horizontal lines go much further than the pink dotted line at the left side of a skew t, it is definitely contaminated.

By going back to the original sounding, you can see how all of these parts work and hopefully you understand a little better how to read this and other soundings.