Isohyets

http://www.hpc.ncep.noaa.gov/tropical/rain/leslie2000.html

This is an example of a isohyet map of South Florida after the Subtropical Depression Leslie struck the region. These types of maps are designed to try and predict the amount of rainfall within certain areas or indicate how much as fallen already. The contour lines are used to show how much precipitation has fallen within those areas, and to make things even easier they are color coordinated with the key located in the top right portion of the map. This map shows the rainfall amounts in to 2 inch intervals and also shows the South Miami received 17.50" of rain.