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.

Officials in the northern Caribbean are warning of heavy rains and dangerous swells as Tropical Storm Erin approaches the region.

A heat advisory has been issued for the Dallas-Fort Worth area and points east, as a powerful and rapidly intensifying Hurricane Erin churns in the Caribbean.