Will the likelihood of marijuana being detected in a urine test be increased because i am obese and the tested chemical is stored in fat?

Marijuana detection: Yes. Also if you have trauma or recent falls, that can trigger a release of small amounts from fat cells.

Most likely: Yes cannabis is lipid soluble stays longer also depends how much you use how often you use quantity and quality of product.

Not particularly: Everyone other that some bodybuilders, tuned athletes will have > 10% of their body weight as fat, & all will store the drug in available fat if they are frequent users. Your obesity is less of an issue that the intensity and frequency of use.