Relationships between rainfall, temperature, and dryland cotton production

A 25-year database including daily temperatures and precipitation is analyzed for distributions, variations, trends and predictability for 17 counties on the Southern High Plains (SHP). Both minimum and maximum temperatures increase from north to south. However, diurnal temperature spread is distributed in a distinctly west to east fashion: a greater spread is noted in the west than in the eastern counties. In this region of interest, precipitation in terms of volume exhibits uniformity within the central and Southern counties. In the northern counties precipitation increases from west to east. As expected with a data set of this size, no precipitation or temperature trends are noted. A logarithmic distribution is shown to provide a primitive fit to wet-day and dry-day spells. Finally, Markov chain and gamma distribution models are used to describe and predict regional precipitation.