Jan 6 - Liz Claiborne Inc cut its adjusted operating income growth forecast for the second half of 2010 as lower traffic and an aggressive promotional environment hurt its December sales.

Juicy Couture: one of the brands owned by Liz Claiborne Inc

Shares of the clothing maker fell nearly 20 percent to $5.54 in extended trade, after closing at $6.90 on Thursday on the New York Stock Exchange.

Bad weather hurt traffic, especially in Europe and some of the merchandises did not resonate well with shoppers, the company said.

Comparable sales and gross profit in December at Juicy Couture, Lucky Brand and Mexx Europe were "clearly disappointing," Chief Executive William McComb said in a statement.

The company said it now sees adjusted operating income to grow $40-$50 million in the second half of 2010, compared with its prior view of a growth of $80 million.

(Reporting by Renju Jose in Bangalore; Editing by Unnikrishnan Nair)