Typhoon Joan (1997)

Super Typhoon Joan

Typhoon (JMA scale)
Category 5 (Saffir–Simpson scale)
Super Typhoon Joan at peak intensity
Formed	October 13, 1997
Dissipated	October 26, 1997
(Extratropical after October 24, 1997)
Highest winds	10-minute sustained: 195 km/h (120 mph) 1-minute sustained: 295 km/h (185 mph)
Lowest pressure	905 hPa (mbar); 26.72 inHg
Fatalities	1 confirmed, 2 missing
Damage	Over $200,000 (1997 USD)
Areas affected	Marshall Islands, Northern Mariana Islands, Guam, Japan, Hawaii
Part of the 1997 Pacific typhoon season

Typhoon Joan of October 1997 was the longest-lasting super typhoon at the time, maintaining 1-minute maximum sustained winds of at least 240 km/h (150 mph) for 4.5 days. Joan, concurrently with Typhoon Ivan to its west, also became the strongest typhoons at the same time in the northwest Pacific Ocean. The 25th named storm during the active 1997 Pacific typhoon season, Joan developed from the same trough as Typhoon Ivan on October 11. It moved northwestward and later to the west, undergoing explosive deepening to its peak intensity on October 15. One typhoon warning agency estimated that Joan was among the strongest storms on record in the basin, and that Ivan and Joan marked the first occurrence of simultaneous super typhoons. While near peak intensity, Joan passed between Anatahan and Saipan in the Northern Marianas Islands. Later, the typhoon weakened and turned to the north and east, becoming extratropical on October 24.

On Saipan, Typhoon Joan destroyed 37 houses and caused an island-wide power outage. Three people were injured due to boarding up their house during the storm. On nearby Anatahan, high winds caused $200,000 (1997 USD) worth of crop and property damage. Later, high waves affected southern Japan and northwestern Hawaii. On Chichi-jima, Joan caused a boat to capsize, killing one of its occupants and leaving two others missing.

In the first week of October 1997, westerly winds near the equator in the western Pacific Ocean produced troughs – extended areas of low pressure – at a low latitude in the northern and southern hemisphere. The system in the South Pacific eventually developed into Tropical Cyclone Lusi, while the trough in the northern hemisphere eventually spawned two systems – Typhoon Ivan formed to the west, and the system that would eventually become Typhoon Joan developed along the eastern periphery. By October 10, the eastern system consisted of an area of poorly-organized convection, moving slowly to the northwest. On the next day, satellite imagery suggested a circulation had developed. The system increased in size and the convection organized further, prompting the Joint Typhoon Warning Center (JTWC) to initiate advisories on Tropical Depression 28W on October 13. Also on that day, the Japan Meteorological Agency (JMA) estimated that a tropical depression had developed near the Marshall Islands.