The cone of the storm's probable course as of 2 p.m. Sunday. (National Weather Service )
As the eye of Hurricane Sandy loomed over the waters some 500 miles southeast of Washington and the monster storm churned toward the Mid-Atlantic coast at 15 miles per hour, Marylanders braced Sunday for the arrival of a weather system some forecasters were calling potentially the most damaging to hit the United States in 75 years.
Heavy rains and gale-force winds were expected to hit the region Sunday afternoon and evening, and still heavier rains and hurricane-force gusts were expected to strike late Monday and Monday night.
Weathercasters said the storm, currently rated as a Category 1 hurricane, would likely cause everything from flash flooding and widespread power outages to treacherous conditions on the roads.
Ocean City officials ordered a mandatory evacuation of downtown — south of 17th St. — by 8 p.m. Sunday night. Residents in low-lying areas are under a voluntary evacuation order.
Mayor Rick Meehan declared a state of emergency, closing the beaches until further notice.
"This storm will be historic, destructive and life-threatening," said Bernie Rayno, a meteorologist with AccuWeather.com, adding that the collision of a cool, low-pressure system from the Midwest and a warm, high-pressure front moving up the coast would set up unusually favorable conditions for a devastating storm.
People in and around Baltimore were expected to get their first taste of the conditions late Sunday and would see the storm intensify by Monday morning and grow worse throughout the day Monday.
Sandy is expected to drop up to 8 inches of rain by Wednesday, when the worst of its effects should be over.
Forecasters anticipated the center of the storm would come ashore on the New Jersey coast, possibly near Atlantic City, late Monday.
In this storm, though, that fact doesn't matter as much as it normally would, according to Jason Elliott of the National Weather Service.
"It doesn't matter much where the storm hits," he said. "The system will affect an unusually large area. These gale-force winds are going to cover hundreds of miles."
Marylanders scrambled Sunday to prepare for Hurricane Sandy's high winds and heavy rains, stocking up on groceries, filling up gas tanks and clearing storms drains.
The storm's worst is expected Monday, likely wreaking havoc on the morning commute.
In Baltimore, city officials declared a state of emergency. Sandbagging stations in Fells Point drew throngs of people, who sometimes had to wait for a turn with the available shovels to dig from the four-foot mounds of sand.
Residents showed Maryland ID to receive bags for the sand: six for private homes, 18 for businesses or churches.
Eric Ausby filled 18 bags to take to his church, United Baptist, where he serves as a deacon.
"Last time it rained, we got flooded really bad," said Ausby, who shoveled sand at Caroline and Thames streets Saturday. "We have at least six doors that need to be covered. And our doors reach the ground level."
Even as the storm weakened, then restrengthened Saturday, forecasters urged East Coast residents to take the storm seriously: stock up on water and food, secure loose outdoor items such as bicycles and grills, make evacuation plans and have extra batteries, flashlights and blankets on hand. Regional power outages and widespread flooding are likely.
Mark Paquette, a meteorologist with AccuWeather, said the public should be focused on preparing for the storm.
"It is going to perform more like a nor'easter on steroids," Paquette said.
The storm could bring four to eight inches of rain along the Interstate 95 corridor and on the Eastern Shore in Maryland, according to forecasters. Isolated areas could see as much as 12 inches of rain. Western Maryland and parts of West Virginia may receive snow.
A storm surge between four and eight feet is possible from Ocean City to the Connecticut border with Rhode Island, according to the National Weather Service. Surges for the upper Chesapeake Bay are forecast for one to two feet and two to four feet for the Delmarva Peninsula, including the lower Chesapeake. The extent of flooding will depend on when during the tide cycle the surge strikes.
Flying debris and snapped tree limbs could be life-threatening, said Paquette, calling Sandy a once-in-a-lifetime storm.
A mix of factors created Sandy's deadly potential: a hurricane barreling up the coast, conditions in the North Atlantic that won't let the storm push out to sea, and a cold front sweeping in from the west that will boost Sandy's energy, Paquette said.
"It's tremendously rare for it to come together in the spot that it will," Paquette said. He compared it to 1991's "Perfect Storm," which brushed New England and Canada. Only this time, he said, it will "affect millions of people along the I-95 corridor."
Rush hour Monday morning will likely be a mess, with sustained winds between 40 and 50 mph and rain throughout the day, Paquette said. The wind power will increase until it peaks Monday afternoon.