A tropical depression dubbed "Twenty-One-E" continues to build up in the eastern Pacific, AccuWeather reports, and may pose a threat to the Mexican coastline.

Once it depression develops into a full-blown tropical storm, it will be christened "Vance," becoming the 20th named storm of the Pacific season, according to the Associated Press. As far as the U.S. mainland is concerned, the phenomenon poses no immediate risk, according to the Miami-based National Hurricane Center.

Tropical cyclones are classified mainly according to wind speeds. In the northeast Pacific and north Atlantic regions, a storm with one-minute sustained winds of up to 38 miles per hour is known as a "depression." For higher speeds of up to 72 miles per hour, the term "tropical storm" is used. A "hurricane" is defined as a cyclone with even faster winds.

Vince is expected to eventually become a hurricane, AccuWeather predicted. The system is set to strengthen further this weekend as it remains over the warm waters of the eastern Pacific. That environment, the weather network explained, has no disruptive wind shear that could help tear apart a tropical cyclone of this nature.

During the next two days, Twenty-One-E will move toward the west or west-southwest, the Weather Channel said. At least through the weekend, forecasters predict it will stay "well off the Mexican Pacific coast."

More critical will be the beginning of next week when Vance - possibly already a hurricane - is likely to take a northeast turn toward land, the channel warned. Whether or not that turn occurs, predicted depends largely on the development of wind shear, and the meteorologists will need to continually update their predictions.

In the worst-case scenario, however, the southwestern Mexican coastline and the southern Baja California peninsula may end up in the cyclone's path. That would include the popular tourist destinations of Cabo San Lucas, Puerto Vallarta and Mazatlan. Individuals located in the area should continue to closely monitor Twenty-One-E's progress to prepare for a possible impact, the Weather Channel advised.