Hurricane Erin has strengthened into a Category 2 storm as it approaches Puerto Rico and the Virgin Islands, bringing heavy rains that could cause flooding and landslides.

A disturbance in the Atlantic following Hurricane Erin is now expected to track northward, National Hurricane Center data shows.

Hurricane Erin is now a Category 5 storm as it rapidly intensified and threatens the Leeward Islands and Puerto Rico, then will move along the U.S. East Coast

Storms that ramp up so quickly complicate forecasting and make it harder for government agencies to plan for emergencies. Hurricane Erick, a Pacific storm that made landfall June 19 in Oaxaca, Mexico, also strengthened rapidly, doubling in intensity in less than a day.

The first Atlantic hurricane of the season is forecast to bring heavy rain and life-threatening surf and rip currents to the U.S. East Coast this week.

Tracking Hurricane Erin, the first named storm of the Atlantic hurricane season, which weakened to a Category 3 storm early Sunday.

The U.S. Air Force 403rd Wing released footage showing one of its planes entering the eye of Hurricane Erin. By early Tuesday, Erin had lost some strength from previous days and had maximum sustained winds of 115 mph (185 kph),