Fujiwhara effect
Cyclone Olaf then tuned east and moving 100 miles (165 km) east of Western Samoa. On February 16, satellite imagery depicted a well-defined eye as Olaf strengthened into a Category 5 cyclone. Olaf reached a peak intensity of 165 mph with a barometric pressure of 915 millibars. It is possible Olaf could have a lower pressure but official track reports have Olaf at 915 mbar. At the time of peak intensity, the center of the storm was only 70 miles (120 km) northeast of American Samoa and 90 miles (145 km) northwest of Pago Pago. At the same time, Cyclone Olaf underwent a minor Fujiwhara effect with Cyclone Nancy before resuming its southeasterly course. Moving at 10 mph (16 km/h), the cyclone maintained Category 5 status as the eye passed 15 miles east of Ta'u, American Samoa. During that time, a weather station reported a 931 barometric pressure reading.