![]() Cyclone Alan near its peak intensity | |
Meteorological history | |
---|---|
Formed | April 17, 1998 |
Dissipated | April 26, 1998 |
Category 1 tropical cyclone | |
10-minute sustained (FMS) | |
Highest winds | 75 km/h (45 mph) |
Lowest pressure | 992 hPa (mbar); 29.29 inHg |
Tropical storm | |
1-minute sustained (SSHWS/NPMOC) | |
Highest winds | 85 km/h (50 mph) |
Overall effects | |
Fatalities | 10 |
Areas affected | French Polynesia |
IBTrACS | |
Part of the 1997–98 South Pacific cyclone season |
Tropical Cyclone Alan was considered to be one of the worst natural disasters experienced in French Polynesia. The system, first noted as a tropical disturbance on April 17, 1998 east of the Northern Cook Islands, initially moved erratically prior to its designation as Alan upon developing into a tropical cyclone on April 21. The following day, Alan reached its estimated peak intensity with 10-minute maximum sustained wind speeds of 75 km/h (45 mph), posing several forecasting challenges due to difficulties in establishing its location and intensity. On April 23, Alan appeared to become sheared with the low-level circulation center displaced about 20 km (10 mi) from the nearest atmospheric convection. However, over the next day, after the mid-level trough of low pressure shearing the system moved faster than expected, Alan became better organized. While situated about 555 km (345 mi) west-northwest of the French Polynesian island of Tahiti, the system drifted south-southeastward. Early on April 25, Alan passed near to or over the French Polynesian Society Islands of Maupiti, Bora-Bora, and Raiatea. However, strong wind shear pulled the system apart, with visible imagery confirming the system's degeneration into a depression with a fully exposed low-level circulation. The system affected French Polynesia with high winds and torrential rain, causing several landslides on the Society Islands. The landslides resulted in the collapse of two bridges, and also overturned trees, in turn obstructing roads. Overall, ten people died as a result of the system, while thirty others were injured, with a majority of the casualties a result of landslides. On the islands of Raiatea, Taha'a and Huahine, several churches, schools and clinics were damaged, while water and electricity supplies were cut off. On the islands, around 750 houses were destroyed, with 430 and 150 wrecked on Huahine and Ra'iātea, respectively.