This paper estimates rainfall frequencies over a portion of Minnesota's high-density rain gauge network. Daily rainfall data from a grid of 10 km by 10 km cells centered on Minneapolis, MN are used to explore the spatial component of extreme rainfall frequencies. A suite of statistical and graphical techniques, performed on each cell's time series of annual maximum daily precipitation for the period 1958-2002, revealed that the mean annual maxima were highly dependent on the number of observers within each cell. Considerable spatial variability in return-period estimates also resulted from the observer number disparities, as well as the fact that a small proportion of the cells experienced outstandingly large rainfalls. The estimates [...]
