NEW YORK (AP) _ Eastern winemakers and grape farmers say prospects are looking up for the industry on this side of the continent, despite heavy rains that upset the harvest in some states.

The mood contrasts sharply from the widespread gloom of just two years ago, when grape-growing regions - particularly in New York State - were littered with ''For Sale'' signs, vineyards were being plowed under, and farmers were taking seminars in economic survival.

At the time, industry officials complained that the high value of the U.S. dollar against other currencies was making imports so cheap here that they could not compete.

But that advantage has since evaporated with the dramatic plunge of the U.S. currency, especially against the French franc and the Italian lira.

Other developments also have come into play, boosting sales and future prospects for wineries and growers.

-Quality has improved, reflecting the growing sophistication of winemakers, growers and the public.

-Grape prices have risen as surpluses of less popular - but widely planted - grape varieties have been wiped out, and in some cases, turned into shortages.

-Promotional campaigns, subsidized entirely or in part by state money, have begun to pay off in sales and growing acceptance of local products. Legislation in some states also has helped encourage or revitalize the industry.

In New York, the nation's second-largest wine-producer after California, the mood among wineries is ''upbeat, optimistic and confident for the first time in a long time,'' said James Trezise, head of the New York Wine Grape Foundation, an organization funded largely by the state.

Over the last two years, the group has worked up a highly visible ''Class By The Glass'' campaign to put New York wines in restaurants, and another to encourage tourism in the state's four major wine regions.

''I believe the program has really had an impact, not only in terms of sales, but in accessibility,'' he said. ''They are willing to taste, try and buy the wines. So it is making inroads in letting consumers know we exist.''

Along with market invisibility, New York also has battled an image problem with its reputation for heavy, sweet, grapey-tasting wines based on varieties like concord, the main grape in a popular brand of grape jelly.

Such wines may still be popular in many parts of the region. But to those accustomed to the more common European-style tastes, an encounter with a traditional ''New York'' wine can be - to put it politely - rather startling.

That's why a recent column by Howard Goldstein, influential wine writer for the New York Times, stood the industry on its ear.

''Sorry, France. Too Bad, California. Some New York Wines Outshine Even Yours,'' read the headline of the article, in which Goldstein acknowledged ''a wine-making revolution'' under way in this state.

''That article has probably been copied, blown up and posted in every winery from here to Lake Erie,'' observed Lyle Greenfield, owner of the 8- year-old Bridgehampton Winery on the eastern end of Long Island.

''I think the mood is extremely positive,'' he said. ''There's a whole sense that we're not going to be treated like third-raters any more.''

Meanwhile, Trezise said grape farmers are also doing better, thanks to prices that have risen about 15 percent to 20 percent - on top of a 40 percent increase in 1986.

For the first time in years, in fact, there's a scramble on for grapes, Trezise said.

One reason is the booming demand created by wine cooler producers. The other is an aggressive marketing campaign by the National Grape Cooperative Inc., maker of Welch's juices and jellies.

But the upturn must be put into perspective, Trezise warned, saying: ''For a full-time grape grower, this year's prices may be where they can just squeeze by.''

Along Lake Erie, winemaker and grape farmer Doug Moorhead of Presque Isle Wine Cellars said that assessment also is accurate for Pennsylvania.

''Some processors are getting short and starting to raid each other's growers,'' he said recently.

''Growers are happy as jaybirds, because vineyards that were about to go down the tubes are now coming back,'' said Dick Naylor, grower-winemaker at Naylor Wine Cellars in Stewartstown, in southeastern Pennsylvania.

Around Labor Day, however, many were especially hard-hit by a period of heavy rains that stretched from Maryland to upstate New York, upsetting the harvest and reducing croploads.

''We had the potential for one of the finest years we ever had, but now it's turning out differently,'' Naylor said.

In Ohio, the mood was described as ''positive'' by Donniella Winchell, head of the Ohio Wine Producers' Association.

''We're into the second year of a $450,000 promotional campaign, with lots of billboards, print and radio,'' she said, ''Our 800-number for winery information averages 50 to 75 calls a day.''

The number of wineries in Ohio has increased by two, to 46, over the past year, Ms. Winchell said.

In Maryland, popular acceptance of Mid-Atlantic region wines appears to be growing despite some late-season weather problems.

''I think the dollar turnaround has helped, definitely,'' said Bret Byrd, head of the Maryland Wineries Association and of Byrd Vineyards in Myersville.

He said promotional events, such as a recent ''Maryland State Wine Festival'' also had helped raise public awareness of the fledgling industry. The weekend event, partially funded by Carroll County, near Baltimore, featured wines from the state's 13 wineries - up two from last year - food, music and grape-stomping.

In Virginia, Annette Ringwood, state government wine marketing specialist, said the industry's overall outlook was ''very optimistic.'' Virginia now has 38 wineries, up from just six in 1979, she said.

To the north, Connecticut is farther behind, with 10 wineries, up from four in 1980. But active state interest in the industry is contributing to a positive mood among vintners and growers, said Susan Connell, owner of of Crosswoods Vineyards in North Stonington, along Long Island Sound.

In 1978, Connecticut joined many of its neighbors in passing a Farm Winery Act, a bill providing a series of tax breaks and incentives encouraging small wineries.

At Haight Vineyard in Litchfield, to the north, Wayne Stitzer, general manager, estimated that the winery would lose about about 10 percent of its crop, due to various diseases brought on by rains.

Even so, he said, the winery expects to sell everything it makes.

End Adv Oct. 11