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.

After reaching Category 5 over the weekend, Hurricane Erin is now down to Category 2 but the large hurricane is still causing problems off the East Coast of the U.S.