Rain in the forecast for Brazil next week was a bearish weight on the grain market as it remained the primary focus when no daily export sales announcements were reported on Friday morning. Still, early concern about the availability of the Brazilian crops has already been linked to increased U.S. export demand and large grain importers like China will continue making purchase decisions that are heavily influenced by global weather conditions. Dry weather in Brazil is currently the biggest factor, but it is not the only driver of potential strength for trade demand. A weaker dollar has also been helping corn and soybean exports accelerate recently. Favorable shifts in exchange rates only amplify the relative value for U.S. grain over exports from Brazil and other competitors. With U.S. corn priced above Brazil just less than a month ago, the current spread now has corn offers out of the Gulf of Mexico as much as 3.5 percent cheaper than Brazil. The premium for U.S. soybeans over Brazil has also narrowed considerably since October. There were flash sale announcements made on all of the four mornings leading up to Friday, including more soybeans to China and large corn sales made…