Tropical Storm Rosa developed southwest of Mexico on Tuesday morning. At 11:00 a.m. EDT on Tuesday the center of Tropical Storm Rosa was located at latitude 14.7°N and longitude 108.0°W which put it about 385 miles (620 km) southwest of Manzanillo, Mexico. Rosa was moving toward the west-northwest at 9 m.p.h. (15 km/h). The maximum sustained wind speed was 45 m.p.h. (75 km/h) and there were wind gusts to 60 m.p.h. (95 km/h). The minimum surface pressure was 1004 mb.
A distinct center of circulation consolidated in an area of thunderstorms southwest of Mexico on Tuesday morning and the National Hurricane Center designated the system as Tropical Storm Rosa. An inner rainband wrapped tightly around the center. Several other bands of showers and thunderstorms were revolving around the core of Tropical Storm Rosa. The circulation was symmetrical and rainbands were occurring in all parts of the tropical storm. Storms near the core began to generate upper level divergence which was pumping mass away from Rosa.
Tropical Storm Rosa will move through an environment favorable for intensification during the next several days. Rosa will move over water where the Sea Surface Temperature is near 29°C. It will move through a region where the upper level winds are weak and there will be little vertical wind shear. Tropical Storm Rosa could intensify into a hurricane by later on Wednesday.
Tropical Storm Rosa will move southwest of a middle level ridge over northern Mexico. The ridge will steer Rosa in a general west-northwesterly direction during the next several days. On its anticipated track Tropical Storm Rosa will move southwest of Baja California later this week.