Isaias was to turn into a hurricane when it reached the Carolinas on Monday night/NHC

Isaias, a tropical storm at midday Monday, was expected to come ashore along the Carolinas as a hurricane after sundown.

The National Hurricane Center said the storm would bring strong winds and heavy rainfall to the Carolinas' coastlines and then the mid-Atlantic Coast. Tropical storm warnings stretched all the way north to Nantucket Island off of Cape Cod.

"On the forecast track, the center of Isaias will pass well east of the Georgia coast through this afternoon. The center of Isaias will then approach the coasts of northeastern South Carolina and southern North Carolina within the hurricane warning area this evening," the forecast read at 2 p.m. EDT. "The center will then move inland over eastern North Carolina tonight, and move along the coast of the mid-Atlantic states on Tuesday and into the northeastern United States Tuesday night."

While Biscayne and Everglades national parks, along with Canaveral National Seashore had reopened Monday, other park units were closed and awaiting the storm.

• Cumberland Island National Seashore along the Georgia coast planned to reopen Tuesday.
• Fort Pulaski National Monument in Georgia temporarily closed Monday.
• Moores Creek National Battlefield in North Carolina was to close Monday and Tuesday.
• Cape Hatteras and Cape Lookout national seashores, both on North Carolina's Outer Banks, closed during the weekend and were awaiting the storm's outcome before deciding when to reopen.
• In Virginia, Fredericksburg and Spotsylvania National Military Park on Monday afternoon was closing interior roads in the park, while Shenandoah National Park staff was warning visitors to be prepared for 2-4 inches of rainfall and wind gusts up to 25 mph.

"Heavy rainfall from Isaias will result in flash and urban flooding, some of which may be significant in the eastern Carolinas and the mid-Atlantic, through Tuesday night near the path of Isaias up the East Coast of the United States. Widespread minor to moderate river flooding is possible across portions of the Carolinas and the mid-Atlantic. Additionally, quick-responding rivers in the southern Appalachians and Northeast will be susceptible to minor river flooding," the forecast from the National Hurricane Center said.

Tornadoes could be spun off as the storm moves through the Carolinas and might even materialize in eastern Virginia and even southern New England, the agency added.