Ask A Scientist© Weather Archive

name         Maryanne
age          15
Question -   What is drought? How is the forecast for drought made?

Maryanne,

Drought is defined as the condition where the lack
of precipitation over a sufficiently long period
causes a hydrological imbalance.  The effects of
drought include reduced yield of crops, reduced
availability of drinking water, brown lawns, etc.

The National Weather Service, as well as private
forecasting companies, keep track of the deficit
in precipitation in comparison with what is
normally received in the geographic location.  At
a certain deficit level, it is considered a drought,
although the term "drought" is often used very loosely
by the television or newspaper reporters for any
extended dry period.  The extent of bad effects from
lack of precipitation are what makes a drought light
or severe.

David R. Cook
Atmospheric Section
Environmental Research Division
Argonne National Laboratory
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