Climatological drop-size distributions and Z-R relations in Southeast Texas

A unique four-year (December 2004 - September 2008) Joss-Waldvogel disdrometer data set from College Station in Southeast Texas is used to analyze the climatological drop-size distributions and Z-R relations associated with storm types common in the region. Cold fronts account for almost half of the 163 disdrometer-identified storms, while upper level disturbances account for about a third. Weak forcing and warm fronts both account for less than 10% of the storms, but warm fronts can produce large rain amounts because of the widespread nature of the associated precipitation. Warm frontal rain tends to have the smallest drops, while all other storm types have larger drops except if deep convection is absent (which can occur in wintertime cold frontal and upper level forcing scenarios). Z-R relations vary greatly within storm types, but the bias-adjusted regional average Z-R does better in estimating total rainfall than the NEXRAD convective default Z-R in most situations.