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 National Hurricane Center is monitoring two disturbances in the Atlantic—the first poised to approach the northern Leeward Islands later this week and the second near the Cabo Verde Islands—while Hurricane Erin, now a Category 3, heads away from the Caribbean.

Hurricane Erin made a sudden shift in trajectory Wednesday as Category 2 winds raced towards the U.S. East Coast, resulting in closed beaches and a state of emergency being declared in North Carolina.

As of the 8 a.m. Wednesday update, the National Hurricane Center gave the closer tropical wave a 60% chance of forming a tropical depression in the next seven days and a 10% chance of developing in the next two days — unchanged numbers from Monday.

While Erin is expected to take a northward turn in the Atlantic, a new system off the coast of Africa has the National Hurricane Center's attention.

As the peak of the Atlantic hurricane season begins, there's already a threat of more storms. Here's a closer look at the tropics.

Forecasters said Erin should begin to slowly weaken as it increased wind shear. However, it's predicted to remain a major hurricane until late next week.

Hurricane Erin, now a powerful Category 4 storm churning in the Caribbean, is not forecast to hit land, but it will bring large waves and dangerous rip currents to the U.S. East Coast. Here's the latest forecast: