After a slightly higher overnight trade, the CME Group grains look to hang on to those slim gains to start the day Thursday.

Early calls for the grains are corn 1-3 cents higher, soybeans 2-4 higher and wheat unchanged to 2 higher, according to private sources.

Overnight trading found March corn trading 3/4 cent higher at $6.17 1/4 per bushel, while January soybeans were 2 1/2 higher at $11.56 1/4 and March wheat was unchanged at $6.17, according to Barchart.com.

Thursday's expected opening prices continue a 3-day surge, due largely to mounting crop weather stress in South America. Meanwhile, at home, the outside factors have been mostly friendly for the grains thus far this week.

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With gains slipping, some traders and farmers wonder whether position-clearing and profit-taking could push the grains south moving into the Christmas holiday weekend.

"Momentum is definitely on the longs' side here, but I am slightly concerned over a possible clearing of positions prior to the long holiday weekend," said Agriculture.com Marketing Talk senior contributor NCcorntrader.

Yes, there is still likely momentum left from the South American weather situation, but after the recent extended uptrend, that could change quickly between now and the end of the week, adds Marketing Talk frequent contributor giolucas.

"The weather problem in South America is very bullish, but my take on the trade is that the price will spike up but the big boys will bring it down super fast," he says.

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