MIAMI (AP) — Tropical Storm Polo will rapidly intensify in the Pacific Ocean and become a major hurricane later this week, forecasters said Monday.

Polo could bring heavy rain, rough surf and tropical-storm-force wind to parts of Mexico late Tuesday into early Wednesday, according to an advisory from the Miami-based National Hurricane Center.

Meteorologists predicted Monday that Polo would drop 4 to 8 inches (10 to 20 centimeters) of rain, with isolated totals near 12 inches (30 centimeters), across coastal portions of the Mexican states of Guerrero, Michoacán, Colima, and Jalisco through Thursday. Flooding and mudslides were possible.

Still a tropical storm as of Monday, Polo had maximum sustained winds of 50 mph (80 kph). It was centered about 240 miles (386 kilometers) south of Manzanillo, Mexico, and 200 miles (322 kilometers) southwest of Zihuatanejo. The system was moving northeast at 5 mph (8 kph).

Farther west in the Pacific Ocean, Tropical Storm Odalys was far from land but expected to become a hurricane by midweek.

Odalys had maximum sustained winds Monday of 45 mph (72 kph). It was located nearly 1,400 miles (2,253 kilometers) west-southwest of the southern tip of Mexico's Baja California peninsula. It was moving northwest at 13 mph (21 kph).

In the Atlantic Ocean, Tropical Storm Fay was weakening. Top winds were around 65 mph (105 kph) and Fay was 405 miles (652 kilometers) southwest of the Azores.

No Atlantic hurricanes have formed yet this year, and this year has set a record for the longest a season has begun without a hurricane. The effects of this year's El Nino crush storms before they get going.