https://phys.org/news/2018-09-nasa-eastern-pacific-tropical-storm.html

MODIS data showed that the tropical cyclone's cloud pattern has become better organized, with developing convective banding features and the depression was upgraded to a tropical storm.

MODIS found coldest cloud tops had temperatures near minus 80 degrees Fahrenheit (minus 62.2 degrees Celsius). NASA research has found that cloud top temperatures that cold have the capability to generate heavy rainfall.