https://phys.org/news/2018-09-suomi-npp-satellite-helene-eye.html

The next day, Sept. 11, NOAA's National Hurricane Center noted another satellite image of Helene showed a well-developed closed eyewall and strong band of thunderstorms with cold cloud tops of minus 104 degrees Fahrenheit/minus 76 degrees Celsius (indicating very strong storms) wrapping around the south through east quadrants of the cyclone.

At 5 a.m. EDT (0900 UTC), on Sept. 11 the center of Hurricane Helene was located near latitude 16.0 degrees north and longitude 33.6 degrees west. That's about 620 miles (995 km) west of the southernmost Cabo Verde Islands and about 1,570 miles (2,530 km) south-southwest of the Azores Islands.