Two sources of kona-storm development in the eastern Pacific are studied, together with factors leading to storm intensification. Vertical structure of this subtropical cyclone is considered in terms of sounding data from Hawaiian stations during the storms of February and March 1951. The kona cyclone initially possesses cold-core characteristics, with winds and rainfall amounts increasing with distance from the low-pressure center and reaching a maxima at a radius of 200 to 500 mi. However, with intensification, this cyclone may develop warm-core properties, with rainfall and wind profiles bearing marked resemblance to those of the tropical cyclone. Abstract Two sources of kona-storm development in the eastern Pacific are studied, together with factors leading to storm intensification. Vertical structure of this subtropical cyclone is considered in terms of sounding data from Hawaiian stations during the storms of February and March 1951. The kona cyclone initially possesses cold-core characteristics, with winds and rainfall amounts increasing with distance from the low-pressure center and reaching a maxima at a radius of 200 to 500 mi. However, with intensification, this cyclone may develop warm-core properties, with rainfall and wind profiles bearing marked resemblance to those of the tropical cyclone.