* Corn tumbled on Monday after last week’s eight-year peak * Market weighs weather for U.S. and Brazilian corn crops * USDA May 12 report in focus for gauge of supply strains * Soybeans and wheat firm after retreating on Monday (Recasts with soybeans above $16) PARIS/SINGAPORE, May 11 (Reuters) - Chicago Board of Trade soybean futures jumped 1.8% on Tuesday, surging above $16 a bushel for the first time since September 2012 as traders focused on prospects for tight supplies until late 2022. Corn and wheat futures also posted sharp gains after a steep pullback a day earlier, as the market turned its attention to U.S. government forecasts due Wednesday that are expected to show tightening grain stocks. At 10:02 a.m. CDT (1502 GMT), Chicago Board of Trade July soybean futures were up 30-1/2 cents at $16.18 a bushel. CBOT July corn futures were 15-1/2 cents higher at $7.27-1/4 a bushel and CBOT July soft red winter wheat was up 15-3/4 cents at $7.46-1/4 a bushel. Market participants are now watching for Wednesday’s World Agricultural Supply and Demand Estimates (WASDE), in which the U.S. Department of Agriculture (USDA) will give its first global outlook for 2021/22. “The market is particularly nervous ahead of the first global USDA forecasts for 2021/22,” Commerzbank said, adding that Brazilian forecasting agency Conab will also update crop estimates on Wednesday. Consultancy AgRural on Monday said it had cut its estimate for the country’s second corn crop in the Center South region owing to drought, adding to expectations that Brazilian corn output will be below last year’s. The USDA said after Monday’s market close that U.S. farmers had planted 67% of their intended corn acres as of Sunday, matching the average estimate in a Reuters poll of analysts. The USDA rated 49% of the U.S. winter wheat crop in good-to-excellent condition, up 1 point from the previous week. Analysts on average had expected no change. (Reporting by Gus Trompiz in Paris, Naveen Thukral in Singapore and Mark Weinraub in Chicago Editing by David Goodman and Bernadette Baum) Our Standards: The Thomson Reuters Trust Principles.