The 28-year-old Powell was not at Philips Arena while the Hawks played the Portland Trail Blazers.
"We are aware of the traffic incident concerning Josh and that he is not at the game tonight," Hawks spokesman Arthur Triche said. "Until we gather more information, we will have no additional comment.
Triche said Powell was arrested late Saturday afternoon before the Hawks' 7 p.m. ET tipoff with Portland. Atlanta police charged Powell with failure to obey an authorized officer who was directing traffic and failure to yield to and obstruction of emergency equipment.
Powell, a seventh-year NBA veteran in his first season as a little-used Atlanta reserve, is averaging 4.9 points in 55 games.
The Atlanta Journal-Constitution reported that Powell tried to turn onto Park Avenue West from Marietta Street, but couldn't move his car because of heavy traffic.
An ambulance was allegedly blocked from clearing the intersection because Powell's car was in the way. The newspaper report said a police officer told Powell several times to move his car, but the player refused.