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Can someone tell these storms to go away?

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There is nothing better than a cold pool on a hot and humid summer day. Don't be caught off guard when swimming is cut short by a lifeguard's shrill whistle. Lightning was spotted. Everyone needs to clear out of the pool for thirty minutes.

As you look up into the sky and see a few bubbling clouds overhead, you ask yourself, where did these storms form? The meteorologists on TV only gave us a 20% chance of showers.

Air mass thunderstorms, popcorn storms, garden variety storms, or single-cell thunderstorms all describe the same thing; The phenomena of random pop-up showers in the afternoon. These storms are difficult to predict, in part due to their small size and short life.

Air mass thunderstorms are common during the summertime. They develop in the afternoon or late in the day, typically only lasting 30 minutes to an hour. During that time, the storm may produce a quick downburst of heavy rainfall, briefly gusty winds, and even small hail.

The formation of these storms is very random. Weather forecast models often don’t pick up where the storms will form due to their small size.

These storms pop up in environments with moisture in the atmosphere, instability, light winds, and daytime heating.

Air mass thunderstorms are weaker than other storms because they do not form by a front or some upper-level forcing mechanism. Daytime heating is what causes these storms to bubble up. As the sun heats the earth’s surface, it warms little parcels of air. The warm and moist air parcels rise, condense, and form clouds higher up in the atmosphere.

The first sign of these storms is developing cumulus clouds, which look like cotton balls in the skies. Eventually, the cumulus clouds start growing vertically, known as the Cumulus Stage in the thunderstorm lifecycle. During this phase, the storm is updraft-dominated. The rising air parcels act as fuel for the thunderstorm. There is no precipitation during this part of the lifecycle.

The air mass thunderstorm reaches the Mature Stage when the water vapor inside the cloud condenses and rain droplets begin forming. When the droplets become too heavy, they fall within the thunderstorm downdraft. If the storm is strong enough, it may produce gusty winds, small hail, and a quick burst of rainfall.

Quickly, the storm becomes downdraft dominant. Air falling through the storm prevents air parcels from rising. The falling air cuts the thunderstorm off from the fuel supply, leading to the storm raining out and dissipating.

Radar view of air mass thunderstorms

Air mass thunderstorms will briefly cause a drop in temperatures as they sit overhead. After their passage, the rain they produce will only add to the mugginess in the air. Temperatures and the heat index often rise after the showers clear out.

Because of how randomly they pop up and the small area coverage, air-mass thunderstorms are tricky to forecast. If it's a hot summer day, but the forecast is calling isolated thunderstorms, it's because your local meteorologist is expecting an air-mass storm somewhere within the viewing area.

You can prepare for the storms by watching the clouds. If you see clouds overhead starting to build vertically or becoming dark in color, this is a good indication a thunderstorm is developing. A quick check of your radar app will confirm your suspicion.

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