Over the weekend, northern portions of the Leeward Islands, the Virgin Islands, and Puerto Rico are expected to receive tropical rain ranging from 2 to 4 inches, with isolated totals up to 6 inches. Flash flooding, landslides and mudslides will be the main concerns over the next several days.

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 weakened slightly on Sunday during an eyewall replacement cycle but will grow larger and stir up surf along the U.S. east coast.

As the hurricane makes its way north well off the coast of the United States, the Space Coast will get rain and beach impact, meteorologists say.

While it's looking very likely that Hurricane Erin will avoid landfall in Florida, the Sunshine State will likely still feel some effects - mainly in rougher coastal waters.

Erin will likely cause heavy surf and rip currents along the Eastern Seaboard starting mid-next week, but nothing in the way of rain, surge, or wind.

U.S. shores are unlikely to see a direct hit, but a strong offshore hurricane can produce massive and dangerous waves well away from its center.