6/28/2021 By Mark Weinraub CHICAGO, June 28 (Reuters) - Chicago Board of Trade corn, soybeans and wheat rallied on Monday, with traders focused on forecasts for heat in the western U.S. Midwest that will quickly dry out soils in major production areas. "The forward forecasts have the heat that is presently over the Pacific Northwest to move over the western corn belt early next week, and even touch parts of Iowa by the end of next week," Charlie Sernatinger, global head of grain futures at ED&F Man Capital, said in a note to clients. Some bargain buying also was noted after the market posted