U.S. weather officials have issued hurricane and tropical storm warnings for parts of Mexico and the southern U.S. state of Texas as Tropical Storm Dolly moves westward after passing over Mexico's Yucatan Peninsula.

The U.S. National Hurricane Center in Miami says Dolly has maximum sustained winds of 110 kilometers an hour and is expected to strengthen into a hurricane Tuesday or Wednesday.  The storm could hit land near the southern Texas border town of Brownsville as early as Wednesday.

Forecasters say Dolly could dump between 10 to 20 centimeters of rain over much of south Texas and northeastern Mexico over the next few days, and trigger tides nearly two meters above normal. 

The storm has prompted evacuations of workers from oil and natural gas installations in the Gulf of Mexico. 

Meanwhile, forecasters say Tropical Storm Cristobal is expected to weaken as it moves northeast, away from the U.S. Atlantic coast.  The storm is 450 kilometers southwest of Halifax, Nova Scotia.

In the Pacific Ocean, Tropical Storm Fausto continues to weaken as it moves farther away from Mexico.

The hurricane center has also announced a new tropical storm in the Pacific, Genevieve. At last report, the storm was about 525 kilometers south of Manzanillo, Mexico and heading west. Forecasters say they expect Genevieve to strengthen over the next two days.