Replying to Ways to find shit in snow

so earlier today i had my pvc rail set up at the local junior high that has a small sledding hill. my phone came out of the phone pocket (it wasnt velcrowed securely) some where on the hill, i spent 90 minutes+ looking for it and got some little kids to help. (i told them i would give them 10 bucks if they found it) it is in probably a 200 squaure foot area and is black. i scraped snow off of like 80% of it and was wondering if theres any ways that would help me locate it. it was in a water proof case