Most east Pacific hurricanes originate from a tropical wave that drifts westward across the intertropical convergence zone, and across northern parts of South America. Once it reaches the Pacific, a surface low begins to develop, however, with only little or no convection. After reaching the Pacific, it starts to move north-westward and eventually west. By that time, it develops convection and thunderstorm activity from the warm ocean temperatures but remains disorganized. Once the tropical wave becomes organized, it becomes a tropical depression. Formation usually occurs from south of the Gulf of Tehuantepec to south of Baja California with a more westerly location earlier in the season. In the eastern Pacific, development is more centered than anywhere else. If wind shear is low, a tropical cyclone can undergo rapid intensification as a result of very warm oceans, becoming a major hurricane. Tropical cyclones weaken once they reach unfavorable areas for a tropical cyclone formation. Their remnants sometimes reach Hawaii and cause showers there.