GRAINS-Front-month soy reaches $10 on USDA yield, export data

* Soybeans up after USDA cuts U.S. crop yield estimate

* Corn, soy buoyed by robust weekly U.S. export sales

* Wheat follows soy and corn higher

(Recasts; updates prices, adds quotes, changes byline, changes dateline from previous HAMBURG) CHICAGO, Oct 13 (Reuters) - U.S. spot soybean futures topped $10 a bushel on Friday, the highest in 2-1/2 months, on follow-through buying a day after the U.S. Department of Agriculture lowered its estimate of the U.S. average soy yield, analysts said. Corn futures rose on a bigger-than-expected weekly export sales tally and wheat followed the firm trend despite disappointing export sales. As of 12:42 p.m. CDT (1742 GMT), Chicago Board of Trade November soybeans were up 7-1/2 cents at $9.99-1/2 per bushel after reaching $10.00-1/2, the contract's highest since July 31. CBOT December corn was up 3 cents at $3.52 a bushel and December wheat was up 5-1/2 cents at $4.36 a bushel. Soybeans climbed as the trade digested Thursday's monthly USDA report, in which the government lowered its U.S. soybean yield estimate to 49.5 bushels per acre (bpa), down from 49.9 in September, bucking analyst expectations for an increase.

The USDA also cut its forecast of the amount of soybeans left at the end of the 2017/18 marketing year - the "carry-out" - to 430 million bushels, from 475 million a month ago. "The report was considered friendly on soybeans; carry-out was lowered more than expected, and we had a little yield reduction," said Ag Watch Market Advisors President Dewey Strickler. Soy and corn futures drew additional support from strong weekly U.S. export sales data. The USDA on Friday reported export sales of U.S. soybeans in the latest week at more than 1.7 million tonnes and corn sales at about 1.6 million tonnes, topping a range of trade expectations. Concern about weather in top soy exporter Brazil, where planting is under way, lent support as well. "Brazil's dry soybean regions, Mato Grosso in particular, look unlikely to get enough rain to broadly raise soil moisture for another week or so," said Tobin Gorey of the Commonwealth Bank of Australia. Wheat followed soybeans and corn higher despite lower-than-expected weekly U.S. export sales, and bearish stocks forecasts in the USDA's monthly reports on Thursday. "Wheat is catching the back end of spreading from corn and soybeans. Wheat numbers were negative, and that's all you can say about them," Strickler said. Strength in the broader commodity sector added to bullish sentiment in grains. The 19-market Thomson Reuters CoreCommodity Index was up 0.6 percent after reaching its highest since May.

CBOT prices as of 12:38 p.m. CDT (1378 GMT):

Net Pct Volume

Last change change

CBOT wheat WZ7 435.75 5.25 1.2 33894 CBOT corn CZ7 352.00 3.00 0.9 99028 CBOT soybeans SX7 999.75 7.75 0.8 175765 CBOT soymeal SMZ7 328.50 2.20 0.7 39210 CBOT soyoil BOZ7 33.67 0.39 1.2 50006

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 Michael Hogan, additional reporting by Naveen Thukral, editing by David Evans and Susan Thomas)