Grid of mean annual precipitation for Oklahoma, 1961-1990 base period.

This digital-map data set consists of a grid of mean annual
precipitation, in inches, based on the period 1961-90, for
Oklahoma. The data set was derived from the PRISM
(Parameter-elevation Regressions on Independent Slopes Model) mean
annual precipitation grid for the United States, developed by Daly,
Neilson, and Phillips (1994, "A statistical-topographic model for
mapping climatological precipitation over mountainous terrain:"
Journal of Applied Meteorology, v. 33, no. 2, p. 140-158). The
precipitation grid was used to develop peak-flow regression
equations by Tortorelli, (1997, "Techniques for estimating
peak-streamflow frequency for unregulated streams and streams
regulated by small floodwater retarding structures in Oklahoma,"
U.S. Geological Survey Water-Resources Investigations Report
97-4202.)