* Wheat down despite frost in Russia

* Corn and soybeans follow wheat despite Brazil flooding

* Investors expect bearish supply and demand numbers from USDA

CHICAGO, May 8 (Reuters) - Chicago Board of Trade wheat futures fell on Wednesday despite weather risks in top exporter Russia, highlighting the size of its supply as the country continues to dominate global export markets.

Corn and soybeans followed wheat lower, even as severe flooding continued to impact Brazil's Rio Grande do Sul region. ANEC, a global association of grain exporters, said on Wednesday that exporters may have to redirect exports to avoid the Rio Grande port.

The Chicago Board of Trade's most-active wheat was down 10-3/4 cents at $6.32 a bushel at 12:17 p.m. CDT (1717 GMT).

Corn was trading 9-1/4 cents lower at $4.57-3/4 a bushel. Soybeans were down 19 cents at $12.27-1/2 a bushel.

Recent weather news in Russia and the U.S. has been giving traders some mixed market signals, analysts said. Reports of frost in two of Russia's key grain-growing areas have prompted local officials to warn that the cold weather has caused widespread damage to this year's harvest.

But some traders shrugged off the potentially bullish news on Wednesday, and instead focused on U.S. wheat condition ratings improving this week after rain fell in wheat-producing Kansas and Oklahoma, the USDA report showed.

Meanwhile, some market participants are anticipating the U.S. Department of Agriculture's May supply and demand and crop production reports on Friday to cast a bearish tone over the recent wheat futures rally.

"As far as today is concerned, we're kind of reminded that we've got a pretty big wheat crop coming, and winter wheat conditions are substantially better than they were this time last year," said Ted Seifried, vice president at the Zaner Group.

Grain and oilseed investors also are expecting USDA to report an increase in U.S. end-stocks of corn, wheat and soy in 2024-25, compared with the previous year, said Angie Setzer of Consus Ag Consulting.

"If there's a bearish number on Friday, it'll kill any type of rally," she said. (Reporting by Renee Hickman in Chicago Additional reporting by Michael Hogan in Hamburg and Bernadette Christina in Jakarta Editing by Matthew Lewis)