"If it does follow this track, you're probably going to see a walloping like you haven't seen since Hurricane David (in 1979)," said Rich Thacker, senior forecaster at the National Weather Service in Charleston. "We're not forecasting a direct hit or a really devastating hurricane, but just a good thrashing, it looks like, on Monday."
Jeanne -- which is expected to be a tropical storm by the time it arrives in the Lowcountry -- should pack winds of 40 to 60 mph from late morning to early afternoon with possible gusts to hurricane force, Thacker said. Rain would total 3 to 6 inches with possible flooding and isolated tornadoes, he said.
"We're looking for a really bad day Monday," Thacker said. "We're looking for real nasty conditions."
There also could be around 2 to 4 feet of storm surge around the 8 a.m. high tide or just afterward, Thacker said.
At 6 p.m. Friday, Thacker said "the forecast position by late morning (Monday) is just west of Hilton Head Island. If that does pan out, that's kind of a worst-case scenario for the island."
If the storm goes just offshore, the Hilton Head area won't be affected as bad as if the eye of the storm goes inland toward Savannah and Ridgeland, Thacker said.
The worst of the storm will probably last from about 10 a.m. to 5 p.m. Monday, Thacker said.
William Winn, director of Beaufort County emergency management, said Friday he still was monitoring the storm and waiting to see exactly where it would go.
People "need to be ready (today) to take protective actions," Winn said, but at this point, the public should "wait and watch, and tomorrow we should have a maybe clearer picture."
The public should be ready to act this morning -- "if we put the word out," Winn said.
In case evacuations are ordered, the Red Cross provides a "last-resort safe place to stay," said Larry Rockwell, director of the group's Palmetto Chapter.
"It's important for families to make sure they're prepared, that they know where they're going to go, that they have a family contact outside of this area and notify them when they choose to evacuate and that they have the necessary supplies on hand," Rockwell said. Those necessary supplies include food, water, cash, a change of clothes, essential medications and gasoline in the car.
Florida is already mobilizing residents ahead of the storm, which had maximum sustained winds of near 100 mph Friday night.
More than 800,000 Floridians were urged to evacuate -- again -- as Hurricane Jeanne moved westward Friday and threatened to become the fourth hurricane to pound the state in the past six weeks.
The storm could come ashore somewhere on the state's east coast by Sunday, targeting some of the same areas hit by previous storms and potentially turning piles of still uncleared debris into deadly missiles.
A state hasn't been hit by four hurricanes in a single season since Texas in 1886. Jeanne could cap a devastating run that has thrashed Florida's Panhandle (Ivan), southwest coast (Charley) and the state's midsection (Frances). Together, they have caused billions of dollars of damage and at least 70 deaths in the state.
"I know people are frustrated, they're tired of all this," Gov. Jeb Bush said. "Trust me, their governor is as well."
Crews with bulldozers worked Friday to clear the mess of flattened homes, torn roofs and snapped trees left over when Frances tore through the heart of the state earlier this month.
Nine counties covering most of the state's Atlantic coast issued evacuation orders for residents in mobile homes, on barrier islands or in low-lying areas. That would affect about 817,000 people.
Jeanne, already blamed for at least 1,100 flooding deaths in Haiti, looked earlier this week like it had turned north and safely out to sea, but it made a jagged loop and then headed straight for the Bahamas and Florida.
The timing of the storm raised concern for Jews observing Yom Kippur. The holiest day on the Jewish calendar began at sundown Friday and ends at sundown today. During that period, observant Jews usually do not work or carry cash and many do not travel by car, all of which could hamper their hurricane preparations.
A National Hurricane Center advisory even asked people to look out for Jewish neighbors who may not be listening to radios or watching TV and may not be aware of the hurricane situation.
"I don't know if I will evacuate or not," physician Armand Braun said as he stocked up supplies at a grocery store in Satellite Beach. "Jewish law says you put Jewish requirements aside if there is any danger."
Three other tropical systems were spinning Friday.
Hurricane Ivan's weakened remnants rolled ashore into east Texas and threatened to dump up to 10 inches of rain in the Houston area. But except for some isolated downpours that caused waist-deep street flooding in the Lufkin area, the average rainfall amounts were less than 2 inches as of midday Friday.