 Tropical Storm Koguma at peak intensity over the Gulf of Tonkin on June 12 | |
| Meteorological history | |
|---|---|
| Formed | June 11, 2021 |
| Dissipated | June 13, 2021 |
| Tropical storm | |
| 10-minute sustained (JMA) | |
| Highest winds | 65 km/h (40 mph) |
| Lowest pressure | 996 hPa (mbar); 29.41 inHg |
| Tropical storm | |
| 1-minute sustained (SSHWS/JTWC) | |
| Highest winds | 65 km/h (40 mph) |
| Lowest pressure | 996 hPa (mbar); 29.41 inHg |
| Overall effects | |
| Fatalities | 1 |
| Missing | 2 |
| Damage | >$9.87 million (2021 USD) |
| Areas affected | South China, Vietnam and Indochina |
| IBTrACS | |
Part of the 2021 Pacific typhoon season | |
Tropical Storm Koguma was a weak tropical cyclone that made landfall in Vietnam, causing minor damage. The fourth named storm of the 2021 Pacific typhoon season, the system was first noted as an area of persistent convection on the South China Sea on June 10, with the JTWC assessing the system in its first advisory as a monsoon depression. Tracking west-northwestward, marginally conductive environmental conditions in the area allowed slight intensification while drifting towards Hainan Island. On the next day, the JMA upgraded the system to a tropical depression as it passed to the south of the territory before the agency upgraded the system to a tropical storm on June 12, being assigned the name Koguma. The JTWC; however still treated the system as a tropical depression until 12:00 UTC that day. It continued to move northwest over the warm waters of the Gulf of Tonkin, eventually making landfall in Vietnam over Thanh Hóa by the end of the same day, rapidly weakening afterward.
Koguma caused widespread floods in Vietnam and Laos, being influenced by the prevailing southwest monsoon. Trees and electrical lines in the former were downed by strong winds, while numerous landslides and rivers being overflowed due to rains were confirmed in the latter. Two individuals in Thanh Hóa were reported to be missing due to the storm, while an individual in Yên Bái Province was confirmed dead by the Vietnam Disaster Management Authority, though their exact cause of death is unknown. Preliminary damages at An Vũ, Haiphong were at 2.4 billion đồng (US$104,000) while in Xayaboury stood at ₭94 billion (US$9.77 million).