In what spokesman Michael Hernandez describes as "the biggest evacuation in history," Miami-Dade has expanded its mandatory evacuations orders to Zone C, forcing over 650,000 to leave Florida in a "traffic nightmare" as Cat-5 Hurricane Irma bears down.

An earlier order included just Miami Beach, other low-lying and barrier island areas and all mobile-home residents, but as the storm grew in intensity and the cone of uncertainty narrowed, County Mayor Carlos Gimenez issued the order this afternoon expanded to Zone C.

The expansion now covers Zone B, which encompasses Brickell, Miami’s downtown area and South-Dade, including parts of Cutler Bay, Florida City and Homestead. Evacuation orders also touch Zone C, which includes parts of Coral Gables, South Miami, Miami Shores and North Miami Beach.

More than 650,000 residents are reportedly subject to the mandatory evacuation order – that’s up from the 200,000 who were asked to leave to areas outside of evacuation Zones A and B, Wednesday.

Downtown Miami is described as "a ghost town"...

Miami looks like a Ghost Town due to Evacuation in anticipation of Hurricane Irma #HurricaneIrma #Evacuation #Miami pic.twitter.com/YFFxz8WY0l — Victoire Cogevina (@vhcogevina) September 7, 2017

As the mass exodus begins...

Lines at gas stations were evident everywhere...

As AP reports on resident exclaiming:

"There was no gas and it's gridlock. People are stranded on the sides of the highway," she said. "It's 92 degrees out and little kids are out on the grass on the side of the road. No one can help them."

Irma's eventual path and Florida's fate depends on when and how sharp the powerful hurricane takes a right turn, National Weather Service Director Louis Uccellini said.

"It has become more likely that Irma will make landfall in southern Florida as a dangerous major hurricane," the Hurricane Center said in a forecast discussion Thursday afternoon.

The last Category 5 storm to hit Florida was Andrew in 1992. Its winds topped 165 mph (265 kph), killing 65 people and inflicting $26 billion in damage. It was at the time the most expensive natural disaster in U.S. history.

U.S. Air Force Reserve weather officer Maj. Jeremy DeHart flew through the eye of Irma at 10,000 feet Wednesday and through Hurricane Harvey just before it hit Texas last month.

He said Irma's intensity set it apart from other storms.

"Spectacular is the word that keeps coming to mind. Pictures don't do it justice. Satellite images can't do it justice," DeHart said.

Still unsure...Miami-Dade made it simple...