https://phys.org/news/2018-06-nasa-tropical-depression-04e-heaviest.html

NASA's Aqua satellite passed over 04E on June 15, 2018 at 5:05 a.m. EDT (0905 UTC) and analyzed the storm in infrared light. Infrared light provides temperature data and that's important when trying to understand where the strongest storms within a tropical cyclone are located. The higher the cloud tops, the colder and the stronger the storms.

Infrared data from the Moderate Resolution Imaging Spectroradiometer or MODIS instrument showed coldest cloud top as cold as minus 63 degrees Fahrenheit (minus 53 degrees Celsius).