Weather Watch:  Watches and Warnings 

Flash flooding kills more people per year than either lightning or
tornadoes.  The rapidly rising waters of a stream or dry wash, a dam
or levee failure, or an ice-jam release can happen anywhere in the
United States.  Flooding can occur within minutes or hours after heavy
and long-duration rainfall, destroying bridges, causing mud slides,
and rolling boulders in the swift-moving waters.  Streams with steep
valley walls with little ground cover are particularly susceptible,
especially if the ground is already saturated from previous rainfall.
Flow rates during floods can be hundreds or thousands of times greater
than normal!

A flash flood <watch> means flash flooding is possible in your area.
A flash flood <warning> means a flash flood is occurring or will occur
very soon.

For more information, see
<http://www.nssl.noaa.gov/researchitems/flooding.shtml>.

-David Schultz, NOAA/National Severe Storms Laboratory