Does it sound like a belt squeal? If so, try this: When it is making the noise, take a small cup of water and pour it on the belt to see if the sound changes. You may have a weak belt tensioner and it's allowing the belt to slip. Also, check to make sure the belt tensioner pulley and the belt idler pulley are not locking up. That can happen as well and cause noise. Since this is happening when it warms up, something could be slowly locking up.
I attached a picture of the belt routing and highlighted the two pulleys I'm referring to. Check them. If you are not sure if it is the belt, then when the engine is warm, remove the belt and start the engine for a couple seconds to see if the sound is gone.
Let me know what you find or if you have other questions.
Saturday, May 16th, 2020 AT 11:17 PM