 Typhoon Isa at peak intensity on April 20 | |
| Meteorological history | |
|---|---|
| Formed | April 12, 1997 |
| Extratropical | April 23, 1997 |
| Dissipated | April 24, 1997 |
| Very strong typhoon | |
| 10-minute sustained (JMA) | |
| Highest winds | 155 km/h (100 mph) |
| Lowest pressure | 940 hPa (mbar); 27.76 inHg |
| Category 5-equivalent super typhoon | |
| 1-minute sustained (SSHWS/JTWC) | |
| Highest winds | 270 km/h (165 mph) |
| Lowest pressure | 930 hPa (mbar); 27.46 inHg |
| Overall effects | |
| Fatalities | None |
| Damage | $1 million |
| Areas affected | Pohnpei, Guam, Rota |
| IBTrACS | |
Part of the 1997 Pacific typhoon season | |
Typhoon Isa was the first of a record eleven super typhoons to occur during the 1997 Pacific typhoon season. The second tropical cyclone of the season, Isa developed from a disturbance in the monsoon trough near the Caroline Islands on April 12. It moved erratically at first, though after attaining tropical storm status it curved westward due to the subtropical ridge to its north. Isa very gradually intensified, and on April 20 the typhoon reached peak 1-min winds of 270 km/h (170 mph), as reported by the Joint Typhoon Warning Center; Japan Meteorological Agency reported maximum 10-min winds of 155 km/h (95 mph). After turning northward, it accelerated to the northeast, and merged with a larger extratropical cyclone on April 24.
Early in its duration, Isa caused light rainfall and moderate winds on Pohnpei. Later, a stationary rainband from the typhoon dropped heavy precipitation on Guam during its dry season. Damage in the Guam National Weather Service area of responsibility totaled $1 million (1997 USD$, 1.9 million 2024 USD), the majority of it from crop damage. No deaths were reported.