AT least some of the Bay State's homeless population may face an easier winter this year as frosty temperatures set in over New England.A program to help clothe the homeless aims to gather 10,000 coats this year. The initiative, called Operation Overcoat, is an eight-week drive that encourages the public to donate used coats. The idea is to let people know they can help those in need in a small but meaningful way during tough economic times. "Having a winter coat doesn't solve the issue of homelessness, but it provides a very tangible resource to folks in the cold winter months," says Sue Marsh, executive director of Massachusetts Coalition for the Homeless, which is co-sponsoring the drive. "It's also a way that people can contribute. Maybe they can't afford a donation but can afford to give away a nice but old coat." Estimates vary as to the number of homeless people in the United States. Fred Karnas, executive director of the National Coalition for the Homeless, says there are approximately 3 million, although he says the federal government has estimated there are only about 600,000 to 700,000 homeless. Mr. Karnas notes that public concern for the homeless is still strong although people often don't understand that it's not a short-term social problem. "We've done a survey that seems to reflect that people's sympathy or empathy for the homeless hasn't decreased any," he says. "[But] I think there is frustration that we've built all those shelters and done all these things and there are still people on the streets." Bay State homeless advocates say the homeless population is increasing. One reason for the increase is the slumping New England regional economy and its high unemployment. According to Ms. Marsh, Massachusetts has an estimated homeless population of 20,000 to 24,000. In addition to the homeless, the state is seeing a new population barely able to keep the homes they do have, says Maureen Sullivan, director of public relations for United Way in Boston, which is also co-sponsoring the Operation Overcoat program. Called "the new poor," these people have been unemployed for over a year and their unemployment and health benefits have run out, Ms. Sullivan says. Organizers for Massachusetts' Operation Overcoat program first launched their effort two years ago. In 1989 more than 500 coats were collected over a 10-day period and last year 6,000 coats were collected during a six-week drive. Coats are collected at booths in two major Bay State shopping malls during the drive which lasts until Dec. 8. The need this year, say organizers, is for children's coats. "Seventy-five percent of the [state's] homeless are women and children, are families," says Leslie Medalie, who handles public relations for Operation Overcoat. "In the past, we had a majority of adults' coats. Now we need children's coats." The business community has initiated similar programs for the homeless. Jos. A. Bank Clothiers Inc., a clothing store chain based in Hampstead, Md., started its own clothing program for the homeless four years ago. Customers donate their old suits, sport coats, pants, skirts, and dresses, which the company gives to the homeless. In return, customers receive discounts on new merchandise.