AMNA NAWAZ: Hurricane Isaias has now strengthened into a Category 3 major hurricane as it heads towards the Gulf Coast.

The storm is packing winds up to 120 miles an hour and is expected to make landfall later tonight.

States of emergency have been declared in parts of Alabama, Florida, and Georgia, warning of storm surge up to nine feet and as many as 15 inches of rain in some coastal areas.

All along the coast, residents are rushing to prepare, lining up for gas and boarding up their homes ahead of the storm.

Florida Governor Ron DeSantis today urged people to get ready.

GOV.

RON DESANTIS (R-FL): You will face very hazardous conditions prior to the storm making landfall.

So you really need to finish your preparations now.

You have to execute your plans now.

There's going to be a point in the not-too-distant future where it's not going to be safe to go outside, even though the storm may still be a distance away from reaching the shore.

Do it now.

AMNA NAWAZ: Joining us now is Michael Brennan.

He's director of the National Hurricane Center.

Michael, welcome back.

So, give us the latest that we know about Hurricane Isaias' path.

where and when is it expected to make landfall?

MICHAEL BRENNAN, Director, National Hurricane Center: Well, I can just tell you, Isaias is still a Category 3 hurricane on the Saffir-Simpson scale, with maximum sustained winds of 115 miles per hour, down just a little bit from earlier in the day, but that's just a really minuscule change.

You can see the center of circulation just offshore of the Florida Panhandle here, probably going to move inland on the coast and make landfall in the next couple of hours.

And that's when the worst of the conditions will begin to materialize.

But as you can see here behind me, all of this weather is pushing onshore now.

So conditions are going downhill really, really rapidly.

AMNA NAWAZ: Yesterday, you mentioned to us that it could weaken further as it approaches landfall.

Is that still true?

MICHAEL BRENNAN: Yes, so it's experiencing what we call vertical shear, which hurricanes don't -- they don't strengthen usually in those types of environments.

The storm so far has been able to cling to Category 3 status.

A little bit more weakening is possible right before it makes landfall.

But, for all practical purposes, it really won't matter because the hazards are already baked and set in place.

Even if the storm comes down a little bit from a wind speed perspective, the rain and the storm surge and the wind impacts really won't change much.

AMNA NAWAZ: And are your concerns still largely the same based on what's happened since the last day we spoke, flooding and storm surge mainly for coastal areas, or should folks inland be concerned as well?

MICHAEL BRENNAN: So we're a bit more concerned about inland impacts.

The forward speed has increased today.

It's now moving really, really rapidly at 17 miles per hour.

And what that means is, it can carry the momentum a little bit farther inland.

So I think what we're going to see is the winds and potential power loss extending deep into Alabama portions of Georgia and even Eastern portions of Mississippi, so absolutely not a coastal phenomenon.

These winds are going to spread deep inland.

AMNA NAWAZ: And at this point, would you say it is too late for people to try to evacuate?

If they're not able to, what should they do to prepare?

MICHAEL BRENNAN: At this point, it is much too late to be moving around.

Sun will be going down soon.

Conditions are deteriorating rapidly.

We're already seeing tornadoes form in some of these outer bands.

You just need to be where you're going to be, hunker down, ride out the storm.

Don't be out venturing around looking at it.

AMNA NAWAZ: We're thinking about everybody in the storm's path and wishing them well.

That is Michael Brennan, director of the National Hurricane Center, joining us tonight once again.

Thank you.

MICHAEL BRENNAN: Thank you.