Soybeans fall on Brazilian rain forecasts; corn, wheat up

* Forecasts of rain in Brazil curb soybean prices

* Corn pressured by closing of U.S.-Mexico rail crossings

* Chicago wheat rise after Wednesday's slide

CHICAGO, Dec 21 (Reuters) - Chicago soybean futures fell on Thursday as traders focused on forecasts calling for rain in Brazil, tempering some concerns over yield losses in the world's top oilseed exporter.

Dry weather in Brazil has led forecasters to cut harvest estimates, but rain this month may limit crop damage in the central and northern zones of the South American country, traders said.

The most active soybean contract on the Chicago Board of Trade (CBOT) settled the day down 14 cents, to close at $13.01-3/4 a bushel. Earlier in the session, the contract dipped down to $12.99-1/4 a bushel, the lowest since Dec. 12.

Meanwhile, corn turned up on a technical bounce, consolidating after contract lows in the previous session, as the closure of rail crossings on the Texas-Mexico border has stoked concerns about possible U.S. export disruptions after a record U.S. harvest.

Mexico is the top export market for U.S. corn.

Nearby wheat futures firmed on a technical bounce, recouping some of Wednesday's sharp losses as a weaker dollar lent some support.

The U.S. Department of Agriculture's report on export sales for 2023-2024, in the week ended Dec. 14, were all in line with analysts' estimates.

But analysts noted that while net corn sales topped 1 million metric tons for the 7th consecutive week, the volumes were still the lowest in eight weeks.

"Corn prices are remaining generally weak, I feel, because there is plenty of corn in the U.S.," said Jack Scoville, an analyst with the Price Futures Group in Chicago. "The elevators and processors are said to be full, and farmers have a lot still to sell."

CBOT's most-active corn contract settled up 2-3/4 cents at $4.72-1/2, while wheat closed up 2-1/2 cents at $6.12-1/2 a bushel. (Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Janane Venkatraman, Tasim Zahid , Paul Simao and Jonathan Oatis)