Thunderstorms need warm and moist air to develop. The warm air at the surface creates an unstable environment for the air to rise rapidly. The moisture in this warm air cools and condenses into a cloud, so the more moisture and warm air at the surface, the higher the cumulus cloud can build vertically into a towering cumulus cloud. When the conditions are right for continued growth, it can continue to grow into a cumulonimbus cloud – otherwise known as a thunderstorm cloud!
Three Stages of Thunderstorm Development
There are three stages of the thunderstorm life cycle: the Developing Stage, the Mature Stage, and the Dissipating Stage. Know how to identify each stage so you can get to safety before dangerous conditions develop.
Developing Stage
If a lifting mechanism is present – a passing front, air moving horizontally over mountains, or even afternoon heat from a hot and sunny day – this warm and moist air rises quickly during the Developing Stage. Rain usually does not yet develop as the storm is still developing during this roughly 10 minute process. While the moisture in the cloud may start to form rain droplets, the updrafts are stronger than the weight of the raindrops and keep the drops suspended in the cloud, where they collide with other drops to become larger and heavier.
Characteristics of a Developing Thunderstorm:
- Towering cumulus cloud indicates rising air
- Usually little, if any, rain during this stage
- Lasts about 10 minutes
- Occasional lightning
Mature Stage
When these drops become heavier than the strength of the updraft, the storm has entered the Mature Stage. The rain falling down and pulling cold air with it is called the downdraft. Downdrafts can drastically reduce the surface temperature, even on a hot summer afternoon. As the downdraft hits the ground, it spreads horizontally and can produce a strong gust front with severe-strength straight-line winds exceeding 50 mph. As long as the updraft continues to feed warm air and moisture into the storm, the storm will continue strengthening with lightning, possibly hail, and even tornado development in the strongest storms.
Characteristics of a Mature Thunderstorm:
- Most likely time for hail, heavy rain, frequent lightning, strong winds, and tornadoes
- Storm occasionally has a black or dark green appearance
- Lasts an average of 10 to 20 minutes but some storms may last much longer
Dissipating Stage
However, in most cases, the downdraft will cut off the supply of warm air to the storm after 20 minutes or so. This marks the Dissipating Stage, with reduced rainfall and less frequent lightning, but strong winds remain a danger. The whole process ranges on average from 30 to 60 minutes. However, in severe thunderstorms, the cycle is longer because the structure is a bit different. When the storm is vertically slanted, the downdrafts will not cut off the inflow of warm air, which can allow the storm to last for hours.
Characteristics of a Dissipating Thunderstorm:
- Downdrafts, downward flowing air dominate the storm
- Rainfall decreases in intensity
- Can still produce a burst of strong winds
- Lightning remains a danger
Thunderstorm Safety
To help you stay safe during thunderstorm development, read up on how to prepare for thunderstorms and get answers to commonly asked thunderstorm questions. Additionally, ensure you're up-to-speed on lightning FAQs, which can even tell you how lightning develops.
Image Credits: NWS Preparedness Guide