Tropical Storm Erin slows to 17 mph but is expected to become a hurricane by Friday, likely tracking east of the U.S. East Coast.

Tropical Storm Erin has formed on a path toward the Caribbean and is expected to strengthen to a hurricane later in the week as it passes by Puerto Rico. Most models forecast the storm turning upward into the Atlantic Ocean, but a few see the storm continuing onward to the U.S. mainland.