National Park System units along the East Coast were closing down Wednesday in advance of a potent winter storm, known in some circles as a "bomb cyclone," that was expected to batter the coast through Thursday with gale-force winds, freezing rains, and possibly a foot or more of snow in some parks.

On Wednesday, Cumberland Island National Seashore off the coast of Georgia and Fort Pulaski National Monument farther inland were shuttered, while in South Carolina, Fort Sumter in Charleston Harbor, Fort Moultrie on Sullivan’s Island, the Fort Sumter Visitor Education Center in downtown Charleston, and Charles Pinckney National Historic Site in Mount Pleasant all were closed as well.

Planning to join those parks on Thursday by closing visitor facilities were Cape Lookout National Seashore, Cape Hatteras National Seashore, Fort Raleigh National Historic Site, Wright Brothers National Memorial, and Acadia National Park.

"During the winter storm event, rough surf and ocean overwash are possible," a release from Cape Hatteras said. "Beach access ramps will remain open to off-road vehicles and pedestrians at Cape Hatteras National Seashore, but some beach routes may become hazardous and impassable during both high and low tide conditions."

At Cumberland Island, staff was expecting wind chills in the low 20s and a great chance of "icy precipitation."

The National Weather Service said a "rapidly deepening area of low pressure just off the East Coast of Florida will move northeastward to the Canadian Maritimes by Friday. The storm will produce areas of snow and rain/freezing rain along the Southeast Coast through last Wednesday evening. As the storm continues to move northeastward, snow and rain will develop over parts of the southern Mid-Atlantic Coast that will change over to all snow by Thursday morning."

"The snow may be heavy over parts of the southern Mid-Atlantic Coast overnight Wednesday. In addition, by early Thursday morning, snow will begin to develop over parts of New England and expand into northern New England by Thursday afternoon, continuing into Friday morning," the agency added."The snow may be heavy at times over New England. The snow will end over the Mid-Atlantic by Thursday evening. Additionally, some areas of rain and thunderstorms will develop over parts of southeast Florida on Wednesday into Wednesday evening."

A range of winter storm watches and warnings were in effect from north-central Florida northward through eastern New England.

Acadia was told to brace Thursday for upwards of a foot or more of snow from the storm, which could produce blizzard conditions at times with winds gusting to 45 mph and temperatures falling below zero, the Weather Service said.

While Cape Cod National Seashore in Massachusetts was expected on Thursday to receive only an inch or two of snow, the forecast also called for blizzard conditions with heavy rains followed by snow and winds gusting as high as 65 mph and temperatures falling into the teens.

Winter storms in years past have destroyed the wooden stairs that lead down to Nauset Light Beach at Cape Cod National Seashore. That won't happen with this storm, however, as the stairs already have been demolished as part of a larger project to remove the location's bathhouse, changing room building, concrete plaza, underground electric and water utilities, and septic tank due to beach erosion.

Traveler footnote: What is a "bomb cyclone?" According to the National Oceanic and Atmospheric Association, "Bombogenesis, a popular term used by meteorologists, occurs when a mid-latitude cyclone rapidly intensifies, dropping at least 24 millibars over 24 hours. A millibar measures atmospheric pressure. This can happen when a cold air mass collides with a warm air mass, such as air over warm ocean waters. The formation of this rapidly strengtheining weather system is a process called bombogenesis, which creates what is known as a bomb cyclone."