MEMPHIS, Tenn. (WMC) - Thunderstorms are common in the Mid-South, especially in the Spring and Summer months. This is because of our location. We are relatively close to the Gulf of Mexico and also in an area that frequently sees cold and warm fronts.
In order for storms to form, there must be three ingredients. In the Mid-South, this recipe is usually on the menu several times a month.
1. MOISTURE. As previously mentioned the Gulf of Mexico acts as the moisture source in the Mid-South. On days with multiple thunderstorms, surface winds are out of the south.
2. INSTABILITY. When warm air is at the surface and cooler air is in the air above it, the air will rise. As the air rises and cools, it will eventually condense and form clouds. Thunderstorms will then form within these clouds, if the other ingredients are also present.
3. LIFT. In order for air to rise, it needs lift. This is achieved in many different ways. When the sun comes out, it will warm the surface, which will create a different air density than the surrounding air. The cooler air around this area will sink, so the warmer air will rise. Fronts, which divide warm/moist air and dry/cold air, also create the spark needed for lift to occur. We typically see storms forming along cold fronts in the Mid-South.
For SEVERE thunderstorms, there must also be a 4th component called shear. This is defined as changes in the winds as you go up in the atmosphere, either in direction or speed. This also provides the “spin” needed for tornado development.