Grain and soy futures markets traded lower overnight and mostly lower again during the day session, reflecting the growing uncertainties facing traders. There is Thursday’s March WASDE and expectations that USDA will lower estimates of Argentine soybean and corn production plus Brazilian corn production, but by how much? Some traders wonder how aggressive those estimates might be. According to wire services, the average trade guess for Argentine soybeans is 48.1 MMT versus 54.0 MMT, which would be higher than many private estimates. Weather is always an uncertain factor. Surface water temperatures in the central Pacific Ocean have begun to warm fairly rapidly, and this gives rise to predictions that La Nina may expire rather quickly...