* CBOT soy backpedals from Nov. 30 high

* Unknown destinations buy US soybeans -USDA

* Wheat, corn futures trade firmer

CHICAGO, Dec 12 (Reuters) - Chicago Board of Trade soybean futures backpedaled on Tuesday after reaching their highest price in December as traders assessed risks from unfavorable crop weather in Brazil.

Wheat and corn futures advanced.

Traders continue to closely watch Brazilian weather because it is the world's top soybean supplier and competes with the U.S. for export business. Heat and dryness have hurt crops in northern and central areas.

More hot weather is expected this week, though crop losses are not universal, said Arlan Suderman, chief commodities economist for brokerage StoneX.

"There's very little in this week's forecast to give hope to farmers in dry areas of Center-West Brazil," Suderman said. "Losses are substantial for some farmers, but a short distance away, crops look good."

Reductions in Brazilian harvest estimates are "not big enough cuts yet to demand an increase in U.S. exports," he said

The U.S. Department of Agriculture, in a daily announcement, confirmed sales of 198,000 metric tons of U.S. soybeans to unknown destinations. It was the fifth consecutive session in which the USDA reported a daily sale to China or unknown destinations.

"This good sales momentum was compounded by fears of a deterioration in yield potential in Brazil, where weather conditions seem unfavorable this week," consultancy Agritel said.

Most-active CBOT soybeans were down 14 cents at $13.22 a bushel by 11:55 a.m. CST (1755 GMT). The contract earlier rose to its highest level since Nov. 30 at $13.44.

Losses in energy markets weighed on soybean and soyoil futures, a broker said.

CBOT wheat was up 16 cents at $6.25-1/2 a bushel, after rallying last week on sales of U.S. soft red winter wheat to China. Speculators hold a short position in the market.

"Yesterday we didn't make a wheat sale for the first time in a while," said Jim Gerlach, president of brokerage A/C Trading. "Today's action makes me think maybe we have."

CBOT corn rose 4-1/2 cents at $4.86 a bushel. (Reporting by Tom Polansek in Chicago. Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Sherry Jacob-Phillips, Mark Potter and Andrea Ricci)