Composite rain rates are constructed as a function of varying environmental parameters such as shear, SST, and moisture convergence. These composites illustrate the spatial distribution and magnitude of tropical cyclone rain rates as a function of the environment.
Initial results using shear predictors from the SHIPS model (based on NCEP-NCAR reanalysis and GFS model) agree with previous studies. Weakly sheared tropical cyclones (less than 5 m/s) maintained a reasonably symmetric precipitation field, while moderately sheared (5-10 m/s) cases exhibited an asymmetric appearance. Strongly sheared (greater than 10 m/s) systems boasted the greatest asymmetry. The asymmetry was also a function of storm intensity, which decreased with increasing storm intensity for all shear values. In other words, tropical storms were the most asymmetric while major hurricanes (category 3 and above) were the most symmetric for all shear values. For all cases of storm and shear intensities, the precipitation field was displaced downshear and left of the shear vector.