Why last night’s thunder was so loud.
Like many across the metro area this morning, I woke up to the very loud storms overnight. Unlike the typical summer or spring storms, they were much louder than normal with longer rolling thunder last night. So what was going on?
These storms were what we call “Elevated” thunderstorms. This means they started their lift from where the warm front was above the ground and not from the ground itself like an average thunderstorm. These average thunderstorms we call “surface” based storms form when it’s warm and humid at the ground. The average storm starts it lifts at the surface for this reason. In this case, last night, these storms initially formed the old fashion wayed and were surfaced based but moved into the Carolinas and became elevated.
Why Inversions Matter:
Last night we had a temperature inversion. When looking at the atmosphere’s temperature profiles last night, we look at what we call soundings. Weather balloons produce these, but also satellites and model data can produce similar soundings. The sounding from Greensboro last night and the forecasted sounding from 3 am this morning showed a temperature inversion. Which means it was actually warmer, around 1,000-5,000’ than at the ground. Last night it was 10° warmer at 5,000′ than at the ground. This inversion was caused by the cold air wedge in place yesterday and overnight near the surface with the warmer air aloft. These inversions can trap cold air below them, pollution, fog, moisture, and in this case, it helped trap sound.
So what happened last night?:
The elevated thunderstorms produced lightning, which created the sound of thunder. Normally with a thunderstorm, these thunder sound waves would dissipate and propagate in all directions. Last night due to the inversion, the sound waves got trapped near the ground. This was the equivalent of setting off fireworks in a closed room versus outside in the open.
These inversions can also allow for the sound waves to travel very far distances as well. This is called atmospheric ducting and works on radio waves and other waves. These inversions can make you pick up radio stations and TV stations over the air at very long distances. They are also the main reason we get ground clutter on our First Warn Doppler Radar at night when the sky is clear.
