With high humidity and a warm climate, the northern Gulf Coast is a breeding ground for thunderstorms. Those cumulonimbus clouds rise upward to fill the sky and darken the landscape. As thunderstorms approach, oftentimes the cool air dragged down with the rain hits the ground and spreads out around the storm. On the front of the thunderstorm, we commonly find a gust front or a shelf cloud. It’s an arc of clouds that signals the approach of a thunderstorm.
As warm, humid air rises upward above the sinking cooler air, the temperature falls, the humidity rises, and clouds form. They can be smooth on the front and turbulent underneath. This is the front of the gust, called a gust front. It’s also called a shelf cloud because it can extend outward like a shelf.
When the gust front moves out fast from the thunderstorm, and separates from the cloud it’s called a roll cloud, because the clouds actually roll but the roll is so slow that you don’t really notice until you record it and play it back on fast speed.
You typically notice the cooler air with the gust front as the wind shifts, before the rain starts. It’s also at this point that lightning can start, even before the rain so don’t wait outside to watch too long.