As Andy Doyle reports this week, while supply remains the main driver of sentiment in grain markets, we are now in a definite weather market.Concerns around weather conditions in a number of important growing regions are helping to lift grain futures markets this week. Flooding in Argentina, dryness concerns around the safrinha (second) corn crop in Brazil, along with heightened potential for a La Niña weather pattern have all combined to send prices for cereals and oilseeds higher this week.