Regional Differences in Runoff-Producing Thunderstorms Rainfall in the Southwest

Abstract

Quantitative descriptions of regional differences of rainfall amounts and intensities in the southwest, such as depth-duration frequencies, generally have ignored differences in the storm system that generated the rainfall and have lumped essentially different storm systems together. Thunderstorm rainfall in southern Arizona and New Mexico were analyzed using data from both recording and standard rain gages. The results were somewhat conflicting. Possibly because of more frontal activity and less distance from the Gulf of Mexico., the thunderstorms in eastern New Mexico can be more intense than those in southeastern Arizona. Recording rain gage records suggest that air-mass thunderstorms produce a larger number of more intense short-duration (about 1 hour or less) rains in southeastern Arizona than in other parts of southern Arizona. However, standard rain gage records from southern Arizona indicate that rainfall from individual air-mass thunderstorms may be greater in south-central Arizona than in se or sw Arizona. But frequency analysis of standard gage data from air-mass storms shows that the 100-year point rainfall is about 3 inches in all 3 regions. With more data becoming available, especially from remote areas, more exact separation of thunderstorm types and a better definition of rainfall will soon be possible.