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.

The expected path of a disturbance in the Atlantic Ocean behind Hurricane Erin—with the potential to develop into a cyclone—has shifted since Tuesday, according to data from the National Hurricane Center (NHC).

Hurricane Erin has been downgraded to a Category 3 hurricane but is gaining in size and raising the risk of life-threatening surf later this week along the U.S.

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