IMPORTANT UPDATE : I might have said somthing that could be misleading and therefore I'd like to clarify to avoid any confusion ! Contango is not an excepetional market context, basically a contango just mean that the future delivery of an non-perishable good is higher than it's current market value. Therefore WTI is always in a contango... What is exceptional nowadays is the extreme impact the contango situation has on forward prices.
It's a little detail, but I'd rather like to make it clear ! Contango is normal for oil, but not when it's amplitude is covering almost half of the market spot value !