GRAINS-Soybeans hit 2-1/2-month high after USDA cuts yield estimate

* USDA bucks trade expectations for a higher soy yield

* CBOT corn follows soy higher, rallying from contract lows

* Wheat sags after USDA raises U.S., global stocks view

(New throughout; updates prices, adds quotes, changes byline, changes dateline from previous PARIS/SINGAPORE) CHICAGO, Oct 12 (Reuters) - Chicago soybean futures jumped to a 2-1/2-month high on Thursday after the U.S. Department of Agriculture lowered its U.S. soybean yield estimate in a monthly report, bucking trade expectations for an increase. Corn futures followed soybeans higher, rallying after front-month December set a contract low, while wheat futures retreated. As of 12:55 p.m. CDT (1755 GMT), Chicago Board of Trade November soybeans were up 23-1/4 cents at $9.88-1/2 per bushel after reaching $9.97-3/4, the contract's highest since Aug. 1. CBOT December corn was up 3-1/4 cents at $3.49-1/4 a bushel while December wheat was down 1-3/4 cents at $4.31-1/2 a bushel. Soybean futures surged after the USDA cut its U.S. soy yield estimate to 49.5 bushels per acre (bpa), down from 49.9 in September and below all but one estimate in a Reuters poll.

"There's no question in my mind that the trade was expecting a bigger yield in both corn and beans. They probably could have tolerated an unchanged yield in beans, but to see it drop was quite a surprise," said Mike Zuzolo of Global Commodity Analytics. Corn futures followed soybeans higher, rallying after the December contract fell to a life-of-contract low at $3.42-1/2. Corn firmed despite the USDA raising its U.S. corn yield estimate to 171.8 bpa, above even the highest in a range of trade estimates. "If it wasn't for soybeans making these big gains, corn would be on the negative side right now because there's nothing there to support it," said Karl Setzer, analyst with the MaxYield Cooperative. CBOT wheat turned lower after briefly following soybeans and corn higher. The CBOT December contract touched a six-week low, pressured by the USDA raising its U.S. and global 2017/18 wheat ending stocks forecasts. "The international wheat numbers were devastating, with world production up 7 million tonnes, nearly equal to last year's production," ED&F Man Capital analyst Charlie Sernatinger wrote in a note to clients.

CBOT prices as of 12:57 p.m. CDT (1757 GMT):

Net Pct Volume

Last change change

CBOT wheat WZ7 431.25 -2.00 -0.5 64363 CBOT corn CZ7 348.75 2.75 0.8 296257 CBOT soybeans SX7 989.25 24.00 2.5 234687 CBOT soymeal SMZ7 325.30 10.40 3.3 72866 CBOT soyoil BOZ7 33.30 0.15 0.5 72693

NOTE: CBOT December wheat, December corn and November soybeans shown in cents per bushel, December soymeal in dollars per short ton and December soyoil in cents per lb.

(Additional reporting by Naveen Thukral in Singapore and Gus Trompiz in Paris; Editing by Dale Hudson and Tom Brown)