Wednesday, 17 January 2007: 11:30 AM
An Examination of Central Gulf Coast Rainfall Quantities to Characterize the Hydrologic Impacts of Gulf of Mexico Tropical Systems
214A (Henry B. Gonzalez Convention Center)
Rainfall quantities produced by central Gulf of Mexico tropical systems occurring during the period of 1851 to 2005 and non-tropical precipitation events affecting southeast Louisiana and southern Mississippi from 1832 to 2005 were examined to quantify precipitation amounts and patterns. A database of daily rainfall reports from 1832 to 2005, on which quality control procedures were completed, was assembled for southeast Louisiana and southern Mississippi precipitation reporting stations. In addition, station metadata, provided by the NCDC station metadata repository and actual station records on file at the National Weather Service New Orleans-Baton Rouge forecast office, were also consulted to identify possible data discontinuities due to observing program changes over the extended period of record. An additional database was compiled for the period from 1851 to 2005 for tropical systems passing through two nested grids centered over southeast Louisiana. Hurricane tracks and storm characteristics were assimilated from the revised 1851-2005 hurricane track information compiled by the Atlantic Hurricane Database Re-analysis Project conducted by NOAA's Atlantic Oceanographic and Meteorological Laboratory (AOML) Hurricane Research Division. The two nested grids were established to examine possible effects of storm proximity, angle of incidence with the coast, storm intensity trends, and storm speed on the rainfall patterns of each tropical system from 1851 to 2005 passing north of 28 degrees North latitude and between 93 degrees and 88 degrees West longitude. For rainfall reports prior to 1900, the density of available stations and availability of rainfall records decrease which does limit the full documentation of storm effects prior to 1900. A climatology of tropical systems affecting the central Gulf Coast from 1851-2005 and selected elements which affect their precipitation characteristics will be presented. To place central Gulf Coast rainfall amounts produced by tropical systems in perspective, rainfall quantities produced by non-tropical precipitation events were documented. This comparison establishes a historical context which indicates the threat of extreme rainfall within the watersheds of southeast Louisiana and southern Mississippi exists year-around and is not tropical season dependent which has implications for regional flood mitigation strategies and water management design projects.