Advisory service Pro Farmer, a division of Farm Journal Media, doused hopes for a record U.S. corn crop after a severe windstorm and drought cut yield potential in the top-production state of Iowa.

Following a crop tour of seven top-producing states, Pro Farmer projected that farmers would harvest a corn crop of 14.820 billion bushels based on an average yield of 177.5 bushels per acre and a soybean crop of 4.362 billion bushels based on an average yield of 52.5 bushels per acre.

Both soy and corn forecasts were below the latest estimates from the U.S. Agriculture Department, though the corn crop would be the second-largest ever and soy would be the third-largest if Pro Farmer's projections are realized.

A key reason the corn forecast is lower is due to crop scouts' findings in Iowa, the top U.S. corn producer.

Iowa crop conditions this year have struggled with drought conditions and the Aug. 10 derecho storm that sent hurricane-like winds and hail across the center of the state.

Some veteran crop scouts were shocked by the severity of damage. A fermented, or sour, smell was beginning to waft from some fields where corn stalks were broken and corn kernels littering the ground began to spoil, scouts said.

"It's not going to be fun for these guys come harvest time," said Brian Grete, director of the tour's eastern half.

Without the drought and storm, the state's corn crop would have been massive, Pro Farmer officials said.

"Some of that corn will be harvested, but further yield loss is likely between now and then," Pro Farmer said in its forecast.

Meanwhile, corn futures rose throughout last week as forecasts for dry weather in much of the Midwest threatened to hinder crops in the late stages of development.

"We absolutely need heavy rainfall in a lot of areas," said Brian Hoops, president of broker Midwest Market Solutions. "That is not in the forecast. It was in the forecast and now it is not."

Corn futures were also pushed higher by news of a fresh sale to China.