The U.S. National Hurricane Center said Pamela’s center was about 170 miles (275 kilometers) west-southwest of Mazatlan late Tuesday and was moving north-northeast at about 12 mph (19 kph). The storm had maximum winds of about 70 mph (110 kph).
Pamela was forecast to pass south of the southern tip of the Baja California peninsula during the night and accelerate toward the coast.
The hurricane center warned of the possibility of life-threatening storm surges, flash floods and dangerous winds around the impact area.
Pamela was then expected to weaken while crossing over northern Mexico and could approach the Texas border as a tropical depression by Thursday. The center said remnants of the storm could carry heavy rain to central Texas and southeast Oklahoma.