The December corn contract tends to extend its seasonal uptrend through early meteorological summer before falling off a cliff.The seasonal picture isn’t as clear for November soybeans, though it too tends to post a high in early summer.Chicago wheat has received a lot of attention lately, putting a spotlight on the idea seasonal analysis is based on averages.Every time I write about seasonal analysis, the oldies radio station in my mind automatically starts playing “Turn! Turn! Turn!” by the Byrds. Those of you of a certain age will recall the song starts with the lyrics, “To everything (Turn…