Have you seen this happen this drastically before ? And is it always the front month dropping more than back month or is this very unique because its storage problem ?
12 usd contango is pretty crazy, yep. I personally haven't seen it before but i wasn't checking it back in 2008. I wonder how bad was it then.
Front can also be higher than back, for example, back in 2018 summer, front traded pretty strong premium against back.