A strong storm in the United States

Tornado is a kind of strong wind vortex accompanied by a funnel-shaped cloud column rotating at high speed, which is produced by strong convective movement of air in extremely unstable weather. The wind speed near the center can reach 100 m/s ~ 200 m/s, and the maximum wind speed is 300 m/s, which is several times higher than that near the center of typhoon (generated at sea). It is extremely destructive. The midwest of the United States is mostly grassland landform, which is called the central plain area, and there are few rugged obstacles that disturb atmospheric activities. Because the warm air brought by the Mexican warm current formed a large number of rain clouds, the cold current from northern Canada quickly retreated, and the low pressure continued to develop in the United States, eventually forming a tornado. Interstate 44 between Oklahoma City and Tulsa is called "I-44 Tornado Corridor", where more than 6,543,800 residents are used to the annual tornado season. Every spring, when the dry cold air from the Rocky Mountains crosses this lowland plain and meets the hot and humid air from the Gulf Coast, the tornado will arrive as scheduled. The tornado corridor extends from the Rocky Mountains to the Appalachian Mountains. There are 1000 tornadoes every year here, and the wind speed reaches 500 km/h, and the farmland, houses, people and animals passing by will be destroyed. Tornadoes in the United States swept through many States this year, as if they had been bombed. The scene was tragic and chaotic. Up to now, 350 people have died and the death toll will increase.