1) Midwest (PADD 2) refineries are still operating in the low 80% utilization.
2) Differential increased to ship more crude by rail, which had dropped to a recent low after initial AB cuts.
3) Jason Kenney's new UPC government is looking to extend the Albertan oil production cuts into 2020 as Line 3 looks delayed.
4) With the rise of U.S. ultralight crude, refineries must blend product with a heavier, lower gravity, crude like WCS. With the collapse of Venezuelan exports to the United States and the slowdown of Mayan imports, plus OPEC cuts, there is little alternative to WCS as a blendstock crude for Permian light.
5) Transmountain pipeline decision on Tuesday may have a nominal impact.
I prefer to play the differential through CCX (Canadian crude ETF).