Despite heavy damage inflicted on this year's crop by an unusually severe winter, Virginia wineries have good reason to celebrate. Demand for Virginia wine is high, vineyard owners say, even if grape production is down at some vineyards.

In addition, the quality of the state's vines and wines is improving, according to Treville Lawrence, president of the Vinifera Winegrowers Association. "Now that Virginia wineries are growing vinifera grapes, which alone make the finest wines in the world, they will be able to compete with the established regions," Lawrence said.

A group of Virginia winemakers hosted a public wine and crafts fair Saturday at Elizabeth Worrall's Piedmont Vineyards in Middleburg to show off their wines.

For nearly 200 years, since Thomas Jefferson encountered difficulties in cultivating vines of quality, Virginians have failed to develop a serious wine industry. In the early 1970s, Worrall's French-schooled mother, Elizabeth Furness, turned conventional wisdom on its head by converting her dairy farm into a winery.

She chose not to plant the hardier hybrids, but instead chose the more vulnerable vinifera grapes that agronomists had insisted would not thrive any better today than they had in Jefferson's day.

Bob Harper of Naked Mountain Vineyards was one of the first to follow Furness into the production of vinifera grapes. "We didn't always see eye to eye," Harper said of Furness, "but she was a very gutsy person, and I have a lot of respect for her."

Furness didn't live to see her gamble pay off. Ernest Hufnagel, marketing director for Piedmont, expects the vineyard to break even this year for the first time in its decade of production. The 1985 crop of Chardonnay is nearly sold out three months after its release.

Piedmont is not the only vineyard where sales outstrip supplies. Other winemakers said they can't keep up with demand.

The Harpers of Naked Mountain Winery, which takes its name from a bald peak near the Village of Markham, recall planting their first vines in the late 1970s with the intention of producing wines for their own consumption. By 1982 they harvested enough grapes for 1,000 gallons of wine, a figure that swelled to 3,000 gallons in 1986.

Ten years ago the number of acres planted with hybrid vines exceeded vinifera crops in Virginia by 4 to 1. Now there are about 35 wineries in Virginia, with vinifera grapes on about 1,000 acres and hybrids on less than 400.

According to Bob Harper, Virginia wineries are blessed with advantages over California in the cost of land, irrigation and shipments.

Opportunities abound for tasting the many wines of Virginia. Saturday evening the Radisson Mark Plaza Hotel in Alexandria will host a benefit for the Alexandria Symphony with representatives of seven vineyards showing their wines. On Aug. 29, the 12th annual Virginia Wine Festival will be held at Valley View Vineyards, one mile east of Middleburg on Rte. 50, with representatives of 16 wineries. On Sept. 5, music and wine will mix in a performance of the folk ensemble Trapezoid at the Oasis Vineyard in Hume.