Heavy rain whipped by gale-force winds sparked flash flooding that paralyzed the Carolinas into Virginia Wednesday, as tens of millions of Americans made the annual trek to spend Thanksgiving with family and friends.

The severe weather moved northeast overnight, and could create extremely hazardous driving conditions along Interstate 95 between Washington, D.C. and New York City. The heavy weather is expected to affect traffic at all Northeast airports, which were reporting sporadic flight delays early Wednesday night.

"It could have a tremendous impact," said Maryland State Highway Administration spokeswoman Kellie Boulware. "Of course we can clear drains and assist stranded motorists if need be, but we also rely on the motorists themselves to be cautious."

About 32 million Americans will be on the roads this holiday weekend, with AAA expecting nearly 5 million to board flights, and almost 2 million to catch trains and buses.

By Wednesday night, the storm system moved into the Mid-Atlantic and New England states, and Accuweather.com forecasted the strongest weather would stretch from Ocean City, Maryland to eastern Long Island. Winds in that area will be blowing at around 45 mph, with gusts topping 60 mph.

That could be trouble for organizers of the Macy's Thanksgiving Day Parade in New York City, who might be forced to ground the huge balloons that are the highlight of the parade. Regulations adopted in 1998 ban the balloons when sustained winds exceed 23 mph or gusts exceed 34 mph.

Those driving in northeastern Pennsylvania and the Catskills should be alert for freezing rain that could lead to slick roads after midnight, according to Accuweather.com. Pockets of freezing rain are also possible Thursday morning across upstate New York from Albany to Binghamton.

Winds picked up along Maryland's Eastern Shore on Wednesday, with some gusts strong enough to blow outdoor furniture around, said National Weather Service forecaster Jennifer McNatt. Rainfall totals are expected to hit around 1.5 inches and some flooding occurs along the coast.

More than 2.3 million vehicles are expected to pass through Maryland's toll facilities from now until Sunday, according to the Maryland Transportation Authority. About 382,000 are predicted to cross the Bay Bridge, a dangerous venture in a storm, in either direction.

Maryland's State Highway Administration is working to clear storm drains of branches and leaves and calling in more patrollers to assist motorists in the event of an accident or stranded vehicle. The administration is also preparing for falling branches.

"All our chainsaws are gassed up," Boulware said.

Meanwhile, more coastal rain and mountain snow was forecast Wednesday for the Pacific Northwest and Northern California.

The Carolinas were expected to see more rain and continue the flooding problems, especially along the coastal areas of the Southeast and Mid-Atlantic, according to Weather.com, as well as strong wind gusts. Portions of the road on Hatteras Island, N.C., were closed because of overwash from rains in recent days, while power outages were reported throughout the state.

Slow Going on the Roads

Traffic slowdowns were reported between the Carolinas on I-95, and some ferry service along North Carolina's coast was halted on Wednesday due to the stormy weather. The state Department of Transportation said it would likely not resume until Thanksgiving day.

In Virginia, a tunnel between Norfolk and Portsmouth was shut down because of high water, and the Chesapeake Bay Bridge-Tunnel, which links Virginia Beach and the Eastern Shore, limited vehicles crossing the span to cars and pickup trucks due to sustained winds of 50-60 mph with gusts of up to 65 mph.

"With winds gusting to 65 mph, that's right powerful," said Patricia Sumners, a switchboard operator at the bridge-tunnel. "You get out there on the bay in a high-profile SUV, you better keep both hands on the wheel."

In southeastern Virginia, drivers scrambling to find alternate routes to avoid intersections filled with pooled water and stalled cars. At Langley Air Force Base, where the flight line is only 11 feet above sea level, workers placed sandbags around buildings with a history of flooding and waterproofed computers and electrical equipment.

Poquoson Public Schools closed, and the Midtown Tunnel between Norfolk and Portsmouth was shut down because of high water.

"I've never seen anything like this," Portsmouth police spokeswoman Ann Hope said as she watched the water rise in front of her home. "A while back a car tried to go through the intersection and the wake was so strong it lifted up and moved vehicles onto the sidewalk."

In what officials are calling the largest coordinated effort of its kind, state police from California to North Carolina will have troopers posted along every 10 miles of I-40 as travelers hit the highway for the holiday.

Troopers from all eight states along the 2,547-mile east-west corridor will participate in an effort, called I-40 Care Across America, to reduce the number of fatalities during the busiest travel period. The states participating in the program are California, Arizona, New Mexico, Texas, Oklahoma, Arkansas, Tennessee and North Carolina.

Bill Sadler, a spokesman for Arkansas State Police, said troopers will be watching for violations ranging from drunk driving to speeding, but said officials hope the beefed up presence will encourage safer driving.

"It will, if nothing else, remind motorists that law enforcement is present to encourage these drivers to correct themselves," Sadler said. "They will send the message that motorists should drive carefully."

Joe Bellone was to head from his Long Island home to visit his fiancee's family in upstate New York, and he had a plan to beat the holiday traffic: Leave at 3 a.m.

"Since people are not out, it ends up being not bad," said Bellone, 29.

AAA says 38.3 million Americans will travel at least 50 miles from home, an increase of nearly three percent from last year. Despite increasing prices for hotel rooms, rental cars and airfares, AAA expects airports and highways will be busier than ever.

Nearly 32 million travelers will be on the roads. They'll pay an average of $2.23 for a gallon of gas, about nine cents cheaper than a year ago.

At the Airports

No flight delays were reported at Raleigh-Durham International Airport and only a few minor delays were reported at Charlotte Douglas International Airport Wednesday morning.

The Port Authority of New York and New Jersey anticipated 1.6 million passengers — about 2 percent more than last year — would pass through LaGuardia, John F. Kennedy International and Newark Liberty International airports.

Travelers arriving at Reagan National Airport outside Washington found long lines even before the sun came up Wednesday.

But security officials say they made it through the peak morning flight time pretty well, with travelers getting through security checkpoints in about 10 minutes.

One man heading to Florida said he was surprised by how smooth the morning was, while another woman just a few feet away says the scene was crazy.

"This place looks like not much more crowded than a regular day," said Doug Besharov, who was traveling to Sarasota, Fla.

A Georgetown University student heading home to Connecticut who called himself a novice traveler says he didn't expect any wait — but ended up stuck in a long line to check in.

The Minneapolis-St. Paul Airport was bustling at midmorning, but the crowds weren't overwhelming, airport spokesman Pat Hogan.

"It's certainly busy but we're not experiencing heavier than normal waits."

At Hartsfield-Jackson Atlanta International Airport, more than 1.7 million passengers are expected to pack the terminals during the holiday week — the most since the Sept. 11, 2001, terror attacks.

New security guidelines that limit carry-on liquids have only increased the baggage crush, prompting a 25 percent increase in checked baggage at the airport, said Ben DeCosta, the airport's general manager.

The airport has a new automated baggage system, and officials are hoping it stands up to its greatest challenge yet: Handling the busiest week of the year for the world's busiest airport.

The Transportation Security Administration's $170 million system, which began operating in July, replaces a handful of minivan-sized machines that screened bags for explosives on the airport's cluttered hallways.

Capital News Service's Alia Malik and The Associated Press contributed to this report.