Standardized Anomaly Maps - How to Interpret
The maps below are presented as standardized anomalies with respect to each locale's long-term mean. A
number like +2.0s means a precipitation amount that is 2.0 "standard deviations"
above the locale's long-term average. For a "normal" (bell curve) distribution,this value would be equalled or exceeded only 2.5% of the time. The long-term
mean was computed using data from 1950-95, inclusive.
For the Midwest,
note that precipitation in 1988 was more than two standard deviations below
the mean, while in 1993, it was more than two standard deviations above
the mean. However, for the ten year period from 1985-1994, inclusive,
the average precipitation that fell was nearly equivalent to the long-term
average. Sometimes the "mean" does not mean much!
Midwestern U.S. Drought of 1988
Click on the figure
to enlarge.
Midwestern U.S. Flood of 1993
Click on the figure to enlarge.
Departure of Average 1985-1994 precipitation from long-term average
Click on the figure to enlarge. (Note Midwest's values are pretty close to zero.)
Easily create your own maps such as these.
Check it out.
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