Tropical Depression Nineteen-E's origins can be traced back to a tropical wave that departed from the west coast of Africa in between August 29 and 30. On August 31, it generated Tropical Depression Six, which would later become Hurricane Florence. The wave continued to track westward at low latitudes, leaving Florence behind in the far eastern tropical Atlantic Ocean. The wave eventually moved over Central America and crossed into the far northeastern Pacific Ocean by September 7. The wave then slowed down and leisurely moved westward, south of Mexico for the next week or so. Meanwhile, a mid-level shortwave trough dropped southward from the United States, entering Mexico on September 9. The trough continued to track southward for the next few days and a low- to mid-level low developed just south of the southern tip of the Baja California peninsula on September 12. Around that time, the NHC noted the system had potential for future tropical development. The low moved southwestward for the next several days. The trough and a plume of moisture rushed northward towards the Baja California peninsula just as the tropical wave was arriving. An area of low pressure formed several hundred miles south of the southern coast of Mexico on September 14 at 12:00 UTC. A surface trough with a north-to-south orientation developed over Baja California Sur on September 18 with thunderstorms having developed from the deep tropics to the Gulf of California.
The disturbance moved into the Gulf of California on September 19. A circulation center and more concentrated convection formed along the trough. Despite stronger wind shear and its proximity to land, the disturbance consolidated into a tropical depression around 12:00 UTC. The genesis of Nineteen-E was unexpected, having occurred after the NHC had downgraded the 5-day formation chance to low. The NHC stated that Nineteen-E was the first tropical cyclone to have formed over the Gulf of California based on records dating back to 1949. Six hours later, the depression's maximum sustained winds peaked at 35 mph (55 km/h). Around that time, the NHC noted that banding features had become slightly more defined and an area of strong convection was present in the eastern semicircle. At 00:00 UTC on September 20, the depression's minimum central pressure decreased to 1002 mbar (29.59 inHg). Around 03:00 UTC, Nineteen-E made landfall between the cities of Ciudad Obregón and Guaymas in Sonora. After moving ashore, the rugged terrain of Sonora quickly weakened the depression. Six hours after landfall, the NHC noted that the depression's convection had taken on a more linear look and that it had lost its closed surface circulation. The NHC reported that Nineteen-E dissipated around 12:00 UTC that day. Nineteen-E's remnants continued to travel northward, while causing severe flooding in Mexico. After entering the United States, the remnants tracked eastward and drew in moisture from the Gulf of Mexico, causing flash flooding in several states.