Hurricanes are some of the most destructive storms on Earth. These huge, spinning storms form over oceans. The most powerful hurricanes have winds up to 200 miles per hour. The storms drop heavy rain when they reach land, and their winds can cause huge storm surges. These surges push seawater inland, causing massive flooding. This combination of wind and water can tear apart buildings, roads, and other structures.
Hurricanes are categorized by the strength of their winds, with ratings from 1 to 5. The strongest is a Category 5. Hurricane Harvey came ashore as a Category 4 hurricane. Its winds were reaching 130 miles per hour, pulling roofs off buildings in communities along the coast, including Rockport and Corpus Christi. Its wind speed soon dropped, though, making it a tropical storm. Tropical storms are weaker than hurricanes, with winds of 39–73 miles per hour.
However, Harvey acted strangely, say meteorologists (scientists who study weather). Normally, hurricanes and tropical storms break up quickly once they reach land. Instead, Harvey stayed intact and slowed down, lengthening the amount of time it could do damage.
A weather station near Houston recorded over 51 inches of rain during the storm. That breaks the record for most rain recorded from a single storm in the history of the lower 48 states. The storm also spun off many tornadoes—spiraling columns of air that can destroy everything in their paths.