GRAINS-Corn futures hit over one-year high on Argentine weather worries

Updates for market open, changes dateline from PARIS/CANBERRA to CHICAGO, adds bullets, changes byline

By Heather Schlitz

CHICAGO, Jan 29 (Reuters) - Chicago grain futures surged on Wednesday as underwhelming rainfall and forecasts for hot, dry weather in Argentina's parched corn and soy belt lifted prices, traders said.

Wheat futures also rose on spillover support from corn as well as rising demand.

Meanwhile, traders waited to see if U.S. President Donald Trump will follow through on threats to impose 25% tariffs on imports from Canada and Mexico this weekend, a move likely to spark retaliation from two of the largest U.S. crop importers.

"Tariffs remain the elephant in the room," Terry Linn, vice president of Linn and Associates, said. "There's nervousness about what might happen."

The most active corn contract on the Chicago Board of Trade (CBOT) Cv1 was last up 10-1/4 cents at $4.95-1/2 a bushel as of 1700 GMT (12:00 p.m. CST) after hitting a 15-month high of $4.97-1/2 a bushel.

Corn and wheat were also supported by expectations of tighter world supplies, while a massive soy harvest ramping up in Brazil added a ceiling to soy futures.

CBOT soybeans Sv1 rose 12-1/4 cents to $10.57-1/4 a bushel, hovering near a six-month peak. Wheat Wv1 added 16-1/4 cents to $5.61-1/2 a bushel.

Rain in Argentina has provided only minimal relief for the country's drought-hit corn and soy crops, while showers over Brazil have slowed the soybean harvest and delayed planting for the country's crucial safrinha corn crop.

"The forecast today is showing much more limited rainfall for Argentina and rain returning to soggy areas of Brazil, and it's helping to fuel the strength here today," Linn said.

The Buenos Aires Grains Exchange has already cut estimates for Argentina's corn and soy yields.

Commodity funds have added to their long positions on corn futures as world supplies tighten, providing an additional boost to prices, Jason Snow, vice president at Futures International, said.