Lost gray tabby with blue collar near Lucy Park

I lost my gray tabby cat yesterday around 7:15pm. He's a small-to-medium cat, about 10 pounds, with a bright blue collar and a tiny white heart-shaped patch on his chest. Last seen near Lucy Park, by the playground off Kemp Boulevard in Wichita Falls, and he sometimes darts into the alley behind the laundromat on 9th Street. He has a neat notch in his left ear and a faint meow that sounds like a squeaky toy when he's excited. This cat means everything to me—he's been part of the family since we adopted him last year, and I'm really worried. If you spot him, he might be skittish at first but will warm up if you call his name, Milo.