Expectations of market participants, as well, are a factor. It may have been the expectation of increasing market scarcity last spring that led to the short-lived surge in futures and cash prices. The lack of market fundamentals to justify this trend led to a subsequent reversal in prices. Stock levels are an indicator of readily available supplies. Pipeline capacity - bottlenecks in the system during heavy demand can be a factor in price volatility.
Operational difficulties can arise for a number of reasons including lags in adjustments.
This aspect can be exacerbated by transportation constraints or diminishing volumes in storage.