Because they are wayyy overdue for some Price Cycling, by at least a week maybe two (the article applies more to the Corn Belt and not the Great Lakes, where it often occurs on a Mon or Tue). Some states do this crap, others don’t-the latter will see their prices slowly fall until they reach an equilibrium point, where the average will bounce around that point a little bit day by day. The former will more or less keep on dropping until one chain (usually the same one each time) decides enough is enough and they’re losing too much money (their prices are below wholesale) and unilaterally raises them, at which point their competitors typically will follow suit (turns out most do but some don’t).
[It was a Dope thread which clued me into this strange tho understandable set of patterns]
In Florida Gate Petroleum used to set the trend, but now it seems all other chains are now completely ignoring them and setting their prices significantly higher for some weird reason.