New Precipitation Frequency Estimates for Michigan

The NWS Office of Hydrologic Development published new precipitation frequency estimates for 17 Midwestern and Southeastern states on April 15, as Volumes 8 and 9 of NOAA Atlas 14, a wholly web-based publication available at This is the first update of these estimates since 1963. Precipitation frequency estimates are connected to climate variability, and used as design standards for civil infrastructure systems built to cope with rainfall and runoff. Examples include storm water drainage systems, roads, bridges, small dams, airport runways, stream erosion control, flood insurance rate maps, soil conservation, and many others. These new estimates directly contribute to the preparation of more cost effective designs, plans, maps, etc.; protecting lives and property, and preventing pollution. NWS precipitation frequency estimates, prepared since the 1950s, are cited as design standards in many Federal, State, and Local Government regulations. These new NOAA Atlas 14 volumes will result in new criteria for a large range of engineering and planning projects across these 17 states.

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