Connecticut’s power companies are preparing for Henri’s potential impact on Sunday.

“You need to be prepared for a loss of power for up to five to 10 days,” says Eversource president and CEO Joe Nolan.

Nolan says that he is classifying Henri as a Level 3 event, meaning that up to 49% of the company’s customers could be without power for over a week.

“We really are facing a storm that I can’t recall. Some of the paths that I’m seeing right now, I have not really seen for several decades in this business. It’s a very, very serious storm,” Nolan says.

Places like Stratford and Milford could see a lot of damage when Henri makes landfall on Sunday.

“The thing that worries me the most, it’s going to be slow. I mean we’re talking about the ability for this thing to stall at a minimum of 12 hours,” Nolan says.

Eversource says it will have 4,000 crews out ready to make repairs – the most its ever had.

United Illuminating says that it has doubled its workforce ahead of the storm and is already setting up staging areas. But the company says that there are important things customers can do now ahead of the storm.

“Charge those devices. Make sure you’ve got a good charge on your phone or on your tablet or whatever you’re using, so that you can reach out to people as needed.” says emergency preparedness director Trish Nilsen.

United Illuminating is encouraging people to stay indoors until works can finish making repairs.

Both companies are asking customers to remain patient. They say that it may take a while to access damage once the storm moves out.