A climatology of the structure, frequency and propagation of midlatitude cyclones that affect North Carolina

In this study we use NCEP Reanalysis and TRMM precipitation data to produce a 13-year climatology of the structure, frequency and propagation of midlatitude cyclones that affect North Carolina (NC). Precipitation is the primary water source for replenishing North Carolina's rivers and groundwater reservoirs, which in turn fulfill the water needs of a growing population. As climate and population pressures change, water management and sustainability policies in NC will be increasingly dependent on an improved understanding of the spatial and temporal distribution of regional precipitating systems. Each year mid-latitude cyclones, tropical cyclones, isolated summertime convection, and mesoscale convective systems deliver precipitation to NC.

Previous studies have determined that a large portion of NC precipitation comes from mid-latitude cyclones and their associated fronts. In this study we produce and analyze seasonal composites of the synoptic-scale structure, propagation and precipitation patterns of midlatitude cyclones that travel through NC to answer three main questions: 1) how does the structure and propagation of midlatitude cyclones that deliver rain to NC change on seasonal-to-interannual timescales? 2) how do those changes affect the temporal and spatial variability of precipitation in NC? and 3) how does ENSO affect the structure, frequency and propagation of midlatitude cyclones that affect NC?

This study provides the foundation for a companion study in which we are producing a detailed climatology of radar-observed mesoscale precipitation organization within midlatitude cyclones in NC.