How meteorologists use atmospheric soundings to determine storm instability
When we look at a standard radar loop or check a typically daily forecast app, we are only seeing a two-dimensional snapshot of the weather, what is happening right at the surface where our feet are. But the atmosphere is miles deep, and the real engine behind our weather patterns operates far above our heads.
To truly understand why our weather changes so drastically from one day to the next, meteorologists rely on a tool that provides a vertical slice of the sky: an atmospheric sounding. This helps reveal the exact temperature and moisture traits that dictate our conditions.
By analyzing these soundings, we can pull back the curtain on why our skies are locked into a quiet pattern right now and exactly what will cause a major shift to arrive when the next chance for showers and storms returns.
A weather sounding looks at the vertical profile of the atmosphere, measuring variables from the surface all the way up to where commercial aircraft fly. While the charts we use behind the scenes can look like an overwhelming grid of intersecting lines, the core concepts come down to two primary elements. The temperature profile (the red line) shows the ambient air temperature at various altitudes. Then the moisture profile (the green line) measures the dew point, indicating how much moisture is available at those same heights.
The physical behavior of these lines, and how close they are to one another, tells us whether the atmosphere is fundamentally stable or unstable.
Currently, the atmosphere above Columbia is defined by a highly stable profile. Following a recent cold front, cool air has settled at the surface while a layer of warmer air sits directly above it. In meteorology, this setup is known as a temperature inversion.
To visualize this, think of a rising pocket of air like a hot air balloon. Under normal spring conditions, a balloon filled with warm air wants to keep rising. However, when it encounters an inversion layer aloft, where the surrounding air is warmer than the balloon itself, it loses its buoyancy. The balloon hits a ceiling and stops moving upward.
This inversion acts like an atmospheric lid. Because air is unable to rise freely through this boundary, cloud development is restricted, and thunderstorm formation is almost completely blocked. While this lid is currently keeping our weather quiet and preventing severe setups, it does have a secondary effect: it traps low-level moisture. This trapped moisture explains why we see a stubborn, gray deck of low clouds locking into place for the region.
In the case of our next shower and storm chances on Friday, the sounding profiles will look a bit different. Stronger southerly flow will begin to take over, ushering in humid air into the lower levels of the atmosphere. At the same time, temperatures above the surface will become cooler.
Returning to the hot air balloon analogy, the environmental conditions are now switched up. When a surface parcel begins to rise on Friday, the air gradually gets colder and colder the higher it goes. Since the rising pocket of air stays warmer than its environment, it continues to gradually accelerate upward. This is an unstable atmosphere, and paired with this, also come temperatures and dewpoints that are very close together throughout almost the entire profile. This means that there is a good chance of at the very least heavier showers and potential convection, allowing for rumbles of thunder.
