(Reuters) - A low pressure system located about 275 miles southwest of Cape Verde Islands had a 20 percent chance of becoming a tropical cyclone over the next 48 hours, the U.S. National Hurricane Center (NHC) said Monday.

It was moving westward at about 15 miles per hour, the NHC said.

"Upper-level winds are only marginally conducive for any significant development to occur," the Miami-based center said.

Meanwhile, the NHC was also monitoring the Tropical Storm Ernesto, that strengthened in the western Caribbean Sea on Monday and was forecast to become a hurricane and smack into Mexico's Yucatan Peninsula.

(Reporting by Soma Das in Bangalore; editing by Carol Bishopric)