Extent of available data.
This data layer provides the 30-year normal average April precipitation values for the period of 1981-2010. It was developed by the Minnesota Climatology Working Group at the State Climatology Office, the Minnesota Department of Natural Resources Division of Ecological and Water Resources, and the Minnesota Department of Agriculture. The 30-year normal values are calculated at the beginning of every decade and summarized in a 10 km grid. Changes in precipitation levels, patterns and the time of year it falls can have significant impacts on erosion, groundwater recharge, surface water flow, and vegetation type and growth rates. It is important to have these data to serve as a foundation for comparison to current precipitation levels, and for detecting trends, because precipitation drives and limits many physical and biological processes.