Flash floods occur suddenly and usually within hours of excessive heavy rainfall. Flash floods become raging torrents of water, ripping through neighborhoods, streets, valleys, etc. sweeping away whatever is in their path. Flash floods can also occur with a dam or levee failure. Heavy rain should be a signal that alerts you to the possibility of dangerous flood conditions.
Flood WATCH
issued when conditions look favorable for flash flooding. A WATCH usually encompasses several counties. This is the time to start thinking about your plan of action and where you would go if the water begins to rise.
Flash Flood WARNING
issued when dangerous flash flooding is happening or will happen soon. A WARNING is usually a smaller, more specific area. This can be issued due to excessive heavy rain or a dam/levee failure. This is when you must act quickly as flash floods are an imminent threat to you and your family. You may only have seconds to move to higher ground.
Flash Flood EMERGENCY
issued for the EXCEEDINGLY RARE situations when extremely heavy rain is leading to a severe threat to human life and CATASTROPHIC DAMAGE from a flash flood is happening or will happen soon. Typically, emergency officials are reporting LIFE-THREATENING water rises resulting in water rescues/evacuations.
Source: weather.gov
