No snow, no worries, right? Wrong.

Highway road crews will once again be on full alert in Northwest Indiana Thursday night.

While much of the snow from Wednesday’s blizzard was removed from Interstate 80/94 and Interstate 65 in Lake County, there’s a new threat: black ice.

“That’s a re al concern,” said Jim Pinkerton, spokesman for the LaPorte District of the Indiana Department of Transportation. “The full crew will be out again tonight and that will be one of the things they will be looking at.”

Black ice is dirty ice that remains on pavement. It’s extremely hard to detect, especi ally at night.

And in extremely low temperatures, s alt and other snow-melting agents have a difficult time melting snow.

“When the temperatures dip to zero or below zero it re ally lowers the effectiveness of the s alt to actu ally to be able to melt any of that frozen materi al off the roads,” Pinkerton said. “So, it’s kind of a precarious position.”

The stretch of of I-65 between Crown Point and Lowell, Indiana, is especi ally prone to accumulating b lack ice.

Open farmland allows wind to quickly refreeze melted snow on the highway.

Dozens of vehicle accidents, some fat al, have been reported in that area over the years.

Schools and government agencies in Northwest Indiana were closed Wednesday for the second day in a row.

But the unscheduled winter break is ending Thursday morning, when classes are scheduled to resume and loc al governments are set to reopen for business.