Sales at U.S. retailers declined for the third straight week as storeowners grappled with winter storms and rising gasoline prices that discouraged shoppers during what may be the worst holiday season in five years.

Sales in the seven days through Dec. 15 fell 0.4 percent from a year earlier, following declines of 2.7 percent and 4.4 percent the previous two weeks, Chicago-based ShopperTrak RCT Corp. said yesterday.

This year’s holiday shopping season may grow at the slowest pace since 2002, according to the National Retail Federation. U.S. shoppers finished just 20 percent of their holiday gift buying last weekend, according to a joint survey conducted by the International Council of Shopping Centers and UBS Securities LLC. Consumers may be holding out for lower prices in coming days, analysts said.

“The early read on the season was overly optimistic,” said Fred Crawford, managing director for Southfield, Michigan- based consultant AlixPartners LLP. “It’s going to be a very difficult 2008.”

ShopperTrak forecast a 3.6 percent increase in holiday sales this year. The National Retail Federation in Washington said sales may rise 4 percent this November and December, the slowest since 2002.

Home Depot Inc., Macy’s Inc. and Target Corp. have discounted prices by 50 percent to attract customers during the three months that account for about 30 percent of the industry’s profit. With Christmas on a Tuesday this year, retailers are counting on a surge in buying this weekend from shoppers making last minute purchases, analysts said. [MORE]