Radar-observed characteristics of precipitating systems during NAME 2004

This was due to precipitating systems surviving the westward trip (7 m s -1 ; 3–4 m s -1 in excess of steering winds) from the SMO after sunset, likely because of enhanced environmental wind shear as diagnosed from local soundings. The second, regime B, corresponded to the significant northward/along-coast movement of systems (10 m s -1 ; 4–5 m s -1 in excess of steering winds) and often overlapped with regime A. The weak propagation is explainable by shallow–weak cold pools.

Reanalysis data suggest that tropical easterly waves were associated with the occurrence of disturbed regimes. Gulf surges occurred during a small subset of these regimes, so they played a minor role during 2004. Mesoscale convective systems and other organized systems were responsible for most of the rainfall in this region, particularly during the disturbed regimes.