* U.S. corn, soybean harvests set to be smaller than expected

* Improving weather continues to weigh on the market

* USDA report shows wheat ending stocks improving

CHICAGO, Aug 11 (Reuters) - Chicago soybean and grain futures turned lower on Friday as improving growing weather led investors to anticipate that U.S. Midwest crop conditions will improve, traders said.

Corn and soybean futures had a particularly choppy trading session as a flurry of bearish signs prompted investors to shed risks at the end of the week.

The most-active soybean contract on the Chicago Board of Trade (CBOT) settled 10-3/4 cents lower at $13.07-1/2 a bushel. Corn settled 9 cents lower at $4.87-1/4 a bushel and wheat closed down 11 cents at $6.26-3/4 a bushel.

Soybean futures had been mixed earlier in the session and corn firmed, after the U.S. government forecast that dry conditions early in the growing season would mean smaller harvests of both this fall.

But forecasts from the U.S. Department of Agriculture's (USDA) monthly World Agricultural Supply and Demand Estimates (WASDE) report fell below market expectations.

The corn crop, if realized, would be the second biggest on record due to large acreage and as growing conditions improved during the key development month of July.

Then traders shrugged off USDA news that farmers participating in U.S. crop subsidy programs reported "prevented plantings" by Aug. 9 of 1,421,488 acres of corn, 458,915 acres of soybeans and 640,761 acres of wheat.

"The simple fact is there simply wasn't enough news today to drive the market higher," said Karl Setzer, brokerage research lead with Mid-Co Commodities.

And with many weather forecast models now predicting that the U.S. Midwest won't see a sharp heat wave at the end of August, "the majority of the trade is now expecting to see improving crop conditions next week," Setzer said.

Meanwhile, Chicago Board of Trade wheat futures slumped as the WASDE report showed wheat ending stocks improving, particularly for hard-red winter wheat, said Craig Turner, commodities trader at Daniels Trading.

And the absence of further war escalation in the Black Sea also weighed on wheat futures, traders said. (Additional reporting by Thomas Polansek and Mark Weinraub in Chicago, Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Richard Chang, Kirsten Donovan)