A sudden heavy rain is known as a squall or a downpour. These occur often in monsoon climates, which are generally located near the Equator. Areas with monsoon climates receive heavy rainfall during part of the year, when atmospheric circulation changes, air pressure and wind direction combine to create wet weather. Monsoon rain is often strong, violent and sudden.
Tropical rain forest climates, located near the Equator, are similar to monsoon climates in that they receive a large amount of rainfall. However, unlike monsoon climates, tropical rain forest climate areas receive a large amount of precipitation year-round. There is no pronounced summer and winter; the weather is warm year-round. The cause of the rainfall in a rain forest climate is due not to atmospheric circulation, but to the constant evaporation of water in a continually warm climate.
Sudden heavy rain in temperate climates occurs most often during the summer, when thunderstorms are prevalent. Weather.com says sudden severe thunderstorms are usually caused by cold fronts associated with jet stream currents in the upper atmosphere. A severe thunderstorm usually has one of the following: hail larger than 3/4 of an inch, winds 58 miles per hour and more or tornadoes. Supercell thunderstorms are a special classification of thunderstorm. These storms are like inland hurricanes, creating rotating columns of air and often spawning tornadoes.
If you live or are traveling in an area where sudden heavy rain might hit, there are some steps you can take to ensure that you aren't completely taken by surprise. Carry a fold-up poncho with you in your bag. You should also carry extra sunscreen or bug repellent, in case these are washed off your skin in the rain. When the rain hits, don't go near fast-moving rivers or drainage pipes. Try to take shelter inside a building instead of under a tree, as trees can be hit by lightning.
Sudden heavy rain can also lead to flash floods, which can occur anywhere, at any time. Flash floods can take place several hours after the rainfall. Look out for rapidly rising water, and do not attempt to drive through a flash flood. An automobile can be swept away in only 2 feet of water, according to the National Weather Service. It is difficult to prepare for flash floods as they occur suddenly, but have a safe evacuation route planned in case your area is flooded.
