Here's what you need to know as Hurricane Florence approaches the US

The eastern United States is in preparation mode as a "monster" Category 4 hurricane approaches the southeast coast. Forecasters warn that millions could be affected by the hurricane, and have urged mass evacuations of areas within its path.

What's going on?

On Wednesday morning, the National Hurricane Service issued an alert that Hurricane Florence is "expected to bring [a] life-threatening storm surge and rainfall to portions of the Carolinas and mid-Atlantic states."

Florence is slow moving in its approach but carries maximum sustained winds of up to 130 mph. Dubbed the "Storm of a lifetime," the National Weather Service expects the hurricane to reach the Carolinas on Thursday or Friday, and may linger over the weekend — bringing with it "catastrophic" winds and flooding rainfall.

Updates on #Florence coming shortly. Biggest change from yesterday is the shift south we've made to match latest model guidance, which now all agree on a landfall near Wilmington, NC. Could be one of the most devastating hurricanes in US history. More: https://t.co/B6LhYZTSK4 pic.twitter.com/aJZ9zy0NBt

— WeatherOptics (@weatheroptics) September 11, 2018

The NHS said coastal North Carolina could receive as much as 40 inches of rain in some areas, with storm surges between 9 and 13 feet.

Mandatory evacuation orders impacting as many as 1.7 million people are in place along the coasts of North Carolina, South Carolina and Virginia, and all three states are under a State of Emergency along with Maryland.

More than 1.5-million people are now under a mandatory evacuation order ahead of #Hurricane #Florence's arrival. https://t.co/3PsomfZgRN

— WeatherOptics (@weatheroptics) September 11, 2018

What should I do if I'm in its path?

Ready.gov urges anyone under evacuation orders to do so immediately, and for those staying within the storm's path to stay follow the instructions based on your location via community warning systems.

If you're not under evacuation orders, Ready.gov recommends having at least three days' worth of food, water, medications and emergency supplies for people and pets. Be sure to charge cellphones and keep back-up batteries on hand in case of extended power outages.

More tips on hurricane preparation can be found at the National Weather Service's website.