Excessive precipitation
From Glossary of Meteorology
excessive precipitation
Precipitation (generally in the form of rain) of an unusually high rate.
The expression is usually used qualitatively, but several meteorological services have adopted quantitative limits. In general, formulas for determining criteria for excessive precipitation take the following form: where R is the amount of rainfall in t minutes, and a and b are constants. For longer storm periods, the expressions used are often of the type where T is the time in hours.
