Wisconsin State Climatology Office

RAINFALL FREQUENCY GRAPHICS

Graphs of the rainfall frequency for each of the nine climate divisions in Wisconsin have been generated from the data provided in Huff and Angel (1992).  These division-averaged rainfall frequency estimates are plotted as a family of curves describing  the rainfall totals for 15 storm duration intervals (from 5 minutes to 10 days) as a function of  recurrence intervals ranging 2 months through 100 years.

INTERPRETATION:

For a climate division, the amount of rainfall that could be expected to be equaled for a given recurrence interval typically increases with longer storm durations.  For example, rainfall totals in south central Wisconsin that would have a 50-year recurrence interval  range from 0.73 inches for 5-minute duration through 9.33 inches over a 10-day span.  A 24-hour storm total that would equal 6.06 inches in this division would represent a rain event with a 50-year recurrence time.  
Alternatively, a 24-hour precipitation total of 1.24 inches would have a recurrence interval of 2-months (0.17 years), a total of 2.25 inches would have a one-year recurrence, while a 7.06 inch or greater total would represent a once in 100 year event. A five-day rainfall total of almost three inches (2.99 inches) could occur once in one year, while 9.36 inches would have a recurrence interval of 100 years.

REFERENCES:

Huff, F.A. and J.R. Angel, 1992: Rainfall Frequency Atlas of the Midwest.  Illinois State Water Survey, Champaign, Bulletin 71. 
Available as a 123-page pdf file at http://www.sws.uiuc.edu/pubdoc/B/ISWSB-71.pdf


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Latest revision: 23 November 2007

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URL Address: http://www.aos.wisc.edu/~sco/clim-history/division/graphics/Rainfall_freq/rain_freq-graphics.html