https://phys.org/news/2018-09-nasa-subtropical-storm-joyce-disorganized.html

The Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA's Terra satellite captured an infrared image of Subtropical Storm Joyce at 12:40 a.m. EDT (0440 UTC) on Sept. 13. The MODIS image revealed that the low-level center is exposed to the northwest of a small patch of deep convection (strong thunderstorms that developed).

Infrared data provides temperature information. That small patch of strongest thunderstorms had cloud top temperatures as cold as minus 63 degrees Fahrenheit (minus 53 Celsius). NASA research has shown that cloud tops with temperatures that cold were high in the troposphere and have the ability to generate heavy rain.