https://phys.org/news/2018-10-tropical-storm-sergio-rainfall-gpm.html

The GPM core observatory satellite's Microwave Imager (GMI) and Dual-Frequency Precipitation Radar (DPR) instruments measured rainfall within tropical storm Sergio on October 10, 2018 at 9:13 a.m. EDT (1313 UTC). GPM's radar only viewed storms on the eastern side of Sergio while the GMI swath included storms around the center of circulation. Measurements by GMI indicated that the heaviest rainfall was north of Sergio's eye like feature. Rain was shown by GMI to be falling at a rate of over 2.2 inches (55.9 mm) per hour in that part of the tropical storm. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency, JAXA.

That heavy rainfall is in the forecast as Sergio begins and continues its landfall. Sergio is expected to produce total storm rainfall accumulations of 3 to 5 inches, with local amounts of 10 inches across the central portion of the Baja California peninsula and Sonora.