Subtropical Cyclone Katie
Subtropical Cyclone Katie, unofficially named by researchers, was an unusual weather event in early 2015. After the 2014–15 South Pacific cyclone season had officially ended, a rare subtropical cyclone was identified outside of the basin near Easter Island, during early May, and was unofficially dubbed Katie by researchers.
Source: Wikipedia — Subtropical Cyclone Katie (CC BY-SA 4.0)