How do meteorologists predict that a storm will be a thunderstorm vs just moderate rain?


What indicators do metereologists look for to predict that a thunderstorm will occur vs just rain showers without lightning/thunder?

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It’s been a while since I’ve done any meteorology but I’ll try my best here. The biggest indicator for a possibility of a thunderstorm rather than just some rain is the energy in the atmosphere combined with some instability. The energy part is based on temperatures and humidity. The instability is caused by a change in weather systems like a cold hot air mass coming in contact with a cold air mass. Once a certain number of conditions are met they are somewhat confident there will be a thunderstorm.

Imagine you have a pot of water on the stove and you turn on the heat. The water at the bottom of the pot gets warmer and starts to rise, while the water at the top of the pot gets cooler and starts to sink. This is called convection, and it happens in the air too. When the sun heats up the ground, the air near the ground gets warmer and rises, while the air higher up gets cooler and sinks. This creates a circulation of air that can form clouds.

Now, not all clouds are the same. Some clouds are thin and wispy, while others are thick and fluffy. The thick and fluffy clouds are called cumulus clouds, and they are the ones that can grow into thunderstorms. To make a thunderstorm, you need three ingredients: moisture, instability, and lifting.

Moisture is water vapor in the air. You can feel moisture when the air is humid or sticky. Moisture helps clouds grow bigger and heavier, because water vapor can turn into liquid water droplets or ice crystals inside the clouds. The more moisture there is in the air, the more rain or hail can fall from the clouds.

Instability is when warm air rises and cold air sinks. You can think of warm air as being lighter than cold air, like a balloon filled with hot air. When warm air rises, it cools down and expands, making it even lighter. When cold air sinks, it warms up and compresses, making it even heavier. This creates a difference in pressure between the warm and cold air, which makes the air move faster. The faster the air moves, the more energy it has. The more energy there is in the air, the more lightning and thunder can happen in the clouds.

Lifting is when something pushes the air up from below. This can be caused by many things, such as hills or mountains, cold or warm fronts, or gusts of wind from other storms. Lifting helps trigger thunderstorms by making warm air rise faster and higher, where it can become unstable and form big cumulus clouds.

Meteorologists use different tools to measure these ingredients and see if they are enough to make thunderstorms. They use weather balloons to measure the temperature, pressure, humidity, and wind speed of the air at different heights. They use satellites to take pictures of the clouds from space. They use radars to see how fast and where the rain or hail is falling from the clouds. They use computers to make models that calculate what the weather will do based on these measurements.

By looking at these tools, meteorologists can tell if there is a chance of thunderstorms in a certain area or not. They can also tell how strong or severe the thunderstorms might be, based on how much moisture, instability, and lifting there is in the air. They can also tell how long or short the thunderstorms might last, based on how fast or slow they are moving.

Thunderstorms are caused by cold fronts mixing with warm fronts. So if the weather monitors pick up a cold front moving in along with rain clouds, it’s safe to assume there’s going to be thunder and lightning.