<p>Police issued a warning after a woman was sexually assaulted at Rainbow Beach Park in the South Chicago neighborhood on Saturday morning. </p><p>The woman, 44, was jogging in the park near the 3100 block of East 79th Street at 6:15 a.m. when the man attacked her from behind, police said. He then threw her to the ground, sexually assaulted her and took her phone.</p><p>The suspect is described as a Black man in his 30s wearing a blue and gray shirt and jeans, with brown eyes, short black hair,