The chairman of Woodward & Lothrop yesterday said sales are running almost 50 percent ahead of expectations so far this year and predicted "a very fine year" for Washington's biggest department store chain.

Usually cautious in his outlook, Woodies' chief executive Edwin K. Hoffman told stockholders the company is "more enthusiastic about the future than we have been for some time."

Sales in February, March and April were 12 percent better than last year and May results were up 13 percent, Hoffman reported at Woodward & Lothrop's annual meeting at the D.C. Convention Center.

Though Woodies stepped up its advertising and sales promotion and planned for higher sales volumes, the year's results are "four or five percentage points" better than anticipated, Hoffman said.

"As the economy gradually improved, so did our sales and profits," added Hoffman. He said retail business is getting better because "the rate of inflation is much more satisfactory, interest rates, though high, are well down from this time last year and the mood of the consumer has improved.

Woodies-watcher Eliot Benson, research director of Ferris and Co., described Hoffman as "more optimistic than I've ever seen him." Benson predicted the Washington-based retail chain could earn record profits of $5.50 a share this year after a net of $4.39 a share ($10.7 million total) in 1982.

The company's stock, which sold as low as $25 last fall and was trading for $34 at the beginning of the year has jumped past $50 recently. Answering a shareholder's question about a possible stock split, Hoffman said company executives will meet soon with investment bankers to discuss the issue.

Woodies is implementing a major restructuring of its branch store operations that will relieve sales personnel of housekeeping and inventory chores so they can concentrate on serving customers, Hoffman disclosed.

"No longer will sales people be back in stockrooms counting merchandise or doing the multitude of things which interfered with their being able to properly serve the customer," he said. "Sales people will only take care of customers and sell and sales managers will spend all of their time on the selling floor making certain that our customers' needs are being served." A separate work force will take over the job of stocking shelves.