Much of Georgia will be slammed with sleet, ice, snow and high winds Wednesday, and there could be power outages that will rival the days thousands went without electricity in 2000, according to a National Weather Service briefing given to agencies based at the Georgia Emergency Management Agency’s command center just before noon Tuesday.

“This could be even worse” than the storm of 2000, said meteorologist Dan Darbe.

Also Tuesday. President Obama declared an emergency in the State of Georgia and ordered federal aid to supplement state and local response efforts.

Initially, the weather service had warned of two storms coming through Georgia this week. But Darbe said, “it’s no longer two events. It’s one long winter event” that will have “crippling” ice that will build up on the roads and power lines.

Virtually the entire state will be hit but the worst areas will be Atlanta and east to Athens and Augusta.

The bad weather will start in the early morning hours Wednesday, between 3 a.m. and 5 a.m. Northeast Georgia could get as much a seven to nine inches and metro Atlanta could see four to seven inches, Darbe said.

“The ice is the big story,” he said.

On Wednesday, high winds will make conditions even worse with gusts getting up to 25 mph. Even sustained winds are expected to be high on Thursday – 15-20 mph.

That “will increase the threat of ice on power lines,” Darbe said.

Earlier Tuesday, the winter storm warning posted for the far northern suburbs northward was expanded to include all of metro Atlanta and the region south to the Dublin area, while Gov. Nathan Deal extended the state of emergency declaration to include another 43 counties south of Atlanta.

The new winter storm warning, which was posted at 5:30 a.m. Tuesday, is in effect through 1 p.m. Thursday.

While roads were becoming treacherous across extreme North Georgia, there were no significant travel problems in the immediate Atlanta area late Tuesday morning and motorists had no issues getting around.

That wasn’t expected to be the case Tuesday night into Wednesday.

In an ominous-sounding statement issued Tuesday morning, the Weather Service warned, “this winter storm may be of historic proportions for portions of the area.

“We are looking at significant snowfall totals, especially northeast, and significant ice totals, especially along the I-20 corridor,” the Weather Service said. “The highest ice totals will be in a rough wedge generally from the metro Atlanta area and points east — south of I-85 and north of I-16.”

As expected, overnight rain that began around midnight began mixing with or changing into sleet across the northern suburbs around daybreak Tuesday.

Fortunately, the sleet mostly melted on the roads during the morning rush hour, when traffic was much lighter than normal.

“We don’t want people to have a false sense of security as we wake up this morning and the pavement is wet,” Channel 2 meteorologist David Chandley said. “It looks like Wednesday is going to be a tough day.”

At 7:30, sleet was being reported in Kennesaw, Alpharetta, Holly Springs, Lawrenceville and Dunwoody.

The precipitation should taper off later Tuesday, but redevelop early Wednesday, as metro temperatures hover around the freezing mark “and get colder as the precipitation goes on,” Chandley said.

Chandley put the chance of precipitation across metro Atlanta at 100 percent Tuesday and Wednesday, diminishing to 30 percent Thursday morning. Highs Tuesday will be in the upper 30s, while highs Wednesday will be in the low 30s after morning lows in the upper 30s.

“The duration of the precipitation tomorrow is going to be a whole lot longer than today, and we’re going to have a mixed bag of snow and ice,” he predicted. “We’re going to see a whole bunch of ice.”

Most metro school systems canceled classes Tuesday, and authorities urged motorists to stay off the roads if possible.

Most metro roadways were wet, but not icy, at 7:30 a.m., said Mark Arum in the AM750 and 95.5FM News/Talk Traffic Center. He said the morning rush hour volume was much lighter than normal.

Temperatures at 8 a.m. included 32 in Dallas, 33 in Alpharetta, 34 in Dunwoody and 38 at Hartsfield-Jackson International Airport.

In northwest Georgia, Cartersville and Dalton both reported flurries at 8 a.m., with temperatures of 30 and 28 respectively. Ga. 20 was blocked by icy conditions west of Cartersville, according to the Georgia Department of Transportation.

Snow was also falling in Athens, Gainesville, Rome and Calhoun, and GDOT reported that all lanes of I-75 in Catoosa County were covered with snow and ice. About 9 a.m., the Georgia State Patrol shut down I-75 southbound in Catoosa after eight separate wrecks occurred near Mile Marker 348.

South of there in Gordon County, multiple wrecks — one involving a possible fatality — were reported by sheriff’s deputies on roads made treacherous by snow and ice.

In northeast Georgia, deputies closed I-985 northbound at exit 16 in Hall County because of icing.

While no ice-related power outages had been reported, Georgia Power crews were working to restore service to 88 customers in the Decatur area after a tree fell across utility lines.

After a soggy night, the rain turned to heavy snowfall before daybreak 85 miles northeast of Atlanta in Helen, which could see up to 7 inches of accumulation, forecasters said. The residents of Helen have buckled down, with city employees spending Monday night in local motels so they could report to work. Most everyone else was staying home, bracing for the ice that could keep Helen on lockdown through the weekend.

One person venturing out in Helen was Gary Allen, who was in a race against the clock, not to mention the thermometer.

The 47-year-old truck driver left a Helen motel Tuesday morning with a haul of fresh produce and three stops to make. He was accompanied by sand dollar-size snowflakes which, so far, weren’t sticking to asphalt, as the temperature hovered just above freezing.

“As long as I can beat the ice, I’ll be okay,” said Allen, who never had to worry about such things in his native Jamaica.

But he had been smack dab in the middle of the storm that hit metro Atlanta two weeks ago. Allen, who lives in Austell, was among those stranded on Atlanta’s interstates, spending one night and the much of the following morning in his 18-wheeler on I-20 east of Six Flags.

He planned to steer clear of the interstates Tuesday, but a treacherous drive to Dawsonville, which normally takes about an hour, awaited.

The good news: It appeared he would have little company on the curvy mountain roads. As the sun rose over the tourist-friendly Alpine village, the only other vehicles spotted were snow plows and sand trucks.

Thursday will begin with wake-up temperatures around 27 degrees, but afternoon highs should reach the low 40s.

Staff writers Rhonda Cook, Christian Boone and Greg Bluestein contributed to this article.