### natural phenomenon | flood:

Flash flood
* Many flash floods occur at night making it hard to see the danger.
  * A 'flash flood' is very quick flooding of low-lying land, usually without prior warning. It may be caused by heavy rain or water from melted ice or snow. Flash floods can also happen after the collapse of a dam.
* are a very real threat after rainfall
  - also a hazard in underground caves
  - always a danger, as is quicksand and rocky terrain
* are another classic severe weather event
  - common after heavy rains in the Ozarks
* are common and deadly
  - frequent in New Mexico
  - ravines usually dry, turn into turgid and turbulent rivers
* are common in long, narrow drainage basins, resulting in greater erosion potential
  - the hilly terrain of Southern Ohio
* are dangerous also for buses
  - for a number of reasons
  - frequent and can be lethal
  - just one kind of flood
* are most frequent during the night, and damage annually is greatest in urban areas
  - in mid to late summer, but they can occur anytime
  - of particular concern because of their sudden onset
  - possible during stormy weather and can occur even when the sky is clear overhead
  - rare in deserts and mountains
  - sudden and extreme volume of water that flow rapidly and cause inundation
* are the number one cause of weather related deaths
  - thunderstorm killer
  - weather killer
  - weather-related killer in the United States
  - typically the result of the hillside runoff of heavy rain
  - when it rains very hard on quickly melting snow
  - occur due to dam failure or an ice jam
  - trigger catastrophic mudslides
  - happen without warning
  - make terrible mud slides and can move very quickly
* can occur and cause problems along with high wind and dust storms
  - anywhere when it rains with little or no warning
  - before the local emergency managers have time to issue a warning
* can occur in late spring and throughout the summer
  - or near mountainous areas, on small streams and even in large cities
  - just about anytime of year in the region
  - throughout the year but are more common during the summer monsoon season
  - under several types of conditions
  - very soon after the onset of heavy rain
  - when there sudden thaw after a long cold winter
* can occur with little or no warning - and can reach full peak within minutes
  - warning-and can reach full peak within minutes
  - to no warning
* can pick up cars, campers and mobile homes, roll large boulders and topple trees
  - result from thunderstorms centered over mountains many miles away
  - roll boulders, tear out trees, destroy buildings and bridges
  - strike without warning
  - sweep away everyone and everything in their path
* can take only a few minutes to a few hours to develop
  - minutes to develop
  - tear out trees and destroy buildings and bridges
* carry a deadly cargo of rocks, mud and other debris.
* cause most of the fatalities associated with flooding events.
* come and go in a hurry, but they often swamp cities and even whole regions.
* destroy villages, human life.
* happen often with tornadoes.
* move much faster than most people.
* occur all over the U.S., and can strike with little or no warning
  - during sudden storms in narrow canyons
  - in mountain canyons and valleys and in normally dry washes
  - most frequently in mid to late summer
  - quickly and inundate streets with rapidly moving water
* occur when heavy rain falls in an area
  - sudden thunderstorms dump water on exposed rock
* occur with amazing rapidity
  - little or no warning and can reach full peak in only a few minutes
  - within six hours of the beginning of heavy rainfall
* pose dangers for many towns and cities in Colorado.
* produce the most erosion in badland regions and commonly wear away large areas.
* result from heavy rainfall, river ice jams, snowmelt, and dam or levee failures
  - severe, heavy rain over a short period of time, sometimes only hours
* rise very quickly, but tend to recede almost as fast.
* strike quickly.
+ Thunderstorm, Severe thunderstorms: Severe weather
  * Flash floods happen when slow-moving thunderstorms pour down much more water than usual in a small area. It rains so hard that the water can not soak into the ground fast enough, and the water rushes down the mountainsides or hills into streams and rivers. These streams and rivers cannot carry all the water, so it quickly floods. The most severe flash flood makes the water level rise dangerously in streams, dry places, or canyons. Flash floods can make terrible mud slides and can move very quickly. They can roll big rocks, tear out trees, and destroy buildings and bridges.
  * Flash floods can also happen when two or more thunderstorms hit the same spot, one right after the other. They can happen when a dam bursts open or ice breaks up. Flash floods can also happen when it rains very hard on quickly melting snow.