News Snapshot:
* Forecasts of weekend rains in Argentina keep lid on prices * Cold weather may hit winter wheat crop in U.S. Plains (Adds closing prices, details on market holiday closure) By Christopher Walljasper CHICAGO, Dec 23 (Reuters) - Chicago wheat futures climbed on Friday, gaining for a second consecutive week as frigid temperatures threaten winter wheat crops across the U.S. Plains and into the Midwest. Fresh export activity in soybeans and corn added support, though gains were limited by much-needed rainfall in Argentina that will boost the rival export nation's crop potential. U.S. grain markets will be closed on Monday...
