Atlas of Interoccurrence Intervals for Selected Thresholds of Daily Precipitation in Texas

The U.S. Geological Survey, in cooperation with the Texas Department of Transportation, has produced maps depicting the magnitude and spatial variation of interoccurrence intervals in days of daily precipitation exceeding selected thresholds in Texas. In the report, a Poisson model of precipitation interoccurrence intervals is described. Aprecipitation interoccurrence interval is the time period between two successive rainfall events. Events are defined as daily precipitation equaling or exceeding a specified depth threshold. Ten precipitation thresholds are considered: 0.05,0.10, 0.25. 0.50, 0.75. 1.0, 1.5. 2.0. 2.5. and 3.0 inches. Site-specific mean interoccurrence interval and ancillary statistics are presented for each threshold and for each of 1,306 National Weather Service daily precipitation gages. Maps depicting the spatial variation across Texas of the mean interoccurrence interval for each threshold are presented. Influence of elevation in west Texas and intra-annual variations or month-to-month differences in interoccurrence interval are documented.