Two well documented cases of tradewind disturbances are studied. One disturbance developed into Hurricane Carla (1961) while the other failed to intensify. Initially the two cases appeared to be very similar but on closer inspection the flow patterns in which the disturbances were embedded proved to have significant differences. This paper describes these differences.

Satellite photographs during the summer months frequently reveal a weather situation in which strong convective development is observed over the Rocky Mountains and several hundred kilometers to the east of the mountains, while the region immediately to the lee is essentially cloud free. It is proposed that an orographically induced mesoscale wave phenomenon may produce this situation.