Variability and Spatial Modeling of Fine-Scale Precipitation Data for the Sonoran Desert of Southwest Arizona

We present a unique new set of high spatial resolution precipitation data from a storage gauge network, for the sparsely observed northern Sonoran desert in south-west Arizona. We examine the nature and causes of the highly complex seasonal and spatial variability in the data, using fine-scale maps developed via spatial modeling and interpolation. These high-resolution maps had explained variances approaching 1.00, and precipitation errors of about 1% in winter and about 10% in summer. Seasonal precipitation ranges from near zero to almost 15 in across the area, and shows high interannual variability. Localized convectional processes lead to summer anomalies that are more spatially complex than in winter when broad-scale synoptic and frontal processes cause precipitation. In general, summer and winter precipitation variability are tied to meridional-zonal shifts and east-west movement of the respective anticyclone or trough pattern over the region. Statistical links between major weather stations in the region and precipitation across the area are spatially inconsistent, especially in the west.