More than 1 million people on the southern East Coast of the United States faced mandatory evacuation orders as Hurricane Florence neared Category 5 strength Monday.

The size of hurricane-force winds doubled over 12 hours from 30 to 60 miles across, and the storm was upgraded twice on Monday from Category 3 to Category 4. Evacuation orders are in effect for coastal areas of North Carolina, South Carolina and Virginia.

“The bottom line is that there is increasing confidence that Florence will be a large and extremely dangerous hurricane, regardless of its exact intensity,” as it nears landfall, the National Hurricane Center said in its 10 p.m. forecast update.

The storm is expected to approach the East Coast on Thursday.

But Gulf Coast residents should be relax into “we dodged the bullet” mode. Isaac – which strengthened o a hurricane on Monday, but slowed to a tropical storm late yesterday – is expected to approach the Caribbean later this week.

As of 10 last night, Tropical Storm Isaac was located about 9600 miles east of the Lesser Antilles and was moving west at 16 mph.

Some models suggest Isaac will steadily weaken as it encounters wind shear in a few days. But yet another one shows Isaac becoming a major hurricane.

The hurricane center is also watching a disturbance in the northwest Caribbean that could move into the Gulf of Mexico in a few days.

The hurricane center raised the odds of development to 60 percent on Monday night and said a tropical depression could form Thursday or Friday in the western Gulf.

The hurricane center warned those along the U.S. Gulf Coast from Louisiana to northeastern Mexico to keep an eye on the system.