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.

Hurricane Erin's massive footprint battered Caribbean islands with heavy gusts and downpours Monday, as it threatened rip currents and flooding along the US East Coast later this week even without