Even though it was snowing slowed over Dallas-Fort Worth on Friday morningMotorists are asked to continue to exercise caution as the threat of black ice begins and extends into Saturday morning.

On Friday morning, area highways were wet and there could be slippery areas due to the freezing temperatures. According to the National Weather Service in Fort Worth, conditions could worsen as water left on roads by melting snow refreezes as temperatures fall to freezing Friday evening.

Texas Department of Transportation road crews were still working around the clock Friday morning and are expected to be on duty “for the foreseeable future,” spokeswoman Kenna Mitchell said.

“Crews determine that drivers are driving too fast for the conditions. “We ask drivers not to become overconfident as there is still a risk of icy conditions,” Mitchell said. “Also, exercise caution on bridges and overpasses and continue to monitor the forecast as conditions change throughout the day and into the weekend.”

The North Texas Tollway Authority began plowing toll roads in convoys Thursday evening, using motor graders and truck plows to push snow and slush onto the side of the road and apply de-icing fluid. This work will continue throughout Friday as employees work 12-hour shifts.

“These slow convoys allow us to spread out across the full width of our roads and get to the surface as much as possible,” said spokesman Michael Rey. “…Our goal is to prepare the surface for a hard freeze overnight and tomorrow.”

Dallas officials on Thursday expanded sanding operations on the city’s major streets as they expect road conditions to worsen Friday.

Local and state authorities emphasize that street cleaning is not a substitute for caution in icy conditions.

“We are doing everything we can to mitigate the impact of this storm, but it is an extreme weather event that requires patience, attention and dramatically reduced speeds for travel in winter conditions,” Rey said.