https://phys.org/news/2018-10-nasa-rainfall-hurricane-michael.html

Data from NASA and the Japan Aerospace Exploration Agency's GPM core satellite was combined with data from other satellites to provide a rainfall accumulation analysis using NASA's Integrated Multi-satellitE Retrievals data (IMERG) program. IMERG data are used to calculate estimates of precipitation from a combination of space-borne passive microwave sensors, including the GMI microwave sensor on the GPM satellite, and geostationary IR (infrared) data. The analysis showed IMERG rainfall accumulation estimates during the period from October 1 to 5, 2018 when rainfall was getting more concentrated over the western Caribbean. IMERG indicated that rainfall accumulation totals of over 12.6 inches (320 mm ) fell in the Caribbean Sea east of Honduras during this period.

The system developed into a depression on Sunday, Oct. 7 at 4 a.m. CDT. By 11:55 a.m. EDT, the depression strengthened into a tropical storm and was named Michael. On Oct. 8 at 11 a.m. EDT, Michael became a hurricane.