In years to come, 1978 may be fondly remembered as "the sugar vintage" of California wines. This year's grapes were healthy, handsome and full of promise, as though the vaunted California lifestyle had been imprinted on the vineyards.

During a hectic record harvest, very high levels of sugar were found in red and white grapes of all types. This sugar, acted upon by yeast, ferments into alcohol, thus transmuting and ennobling grape juice. With insufficient sugar, the best grapes won't make wine. With enough, the winemaker has the raw material to create something memorable.

And memorable is only one of the words optimistic winemakers are tossing around when dicussing the potential of their new wines.

"I think this is one of the great years," said Rod Strong of Sonoma Vineyards. Further to the north, near Ukiah, John Parducci, whose winery bears his name, forecast "some of the most fantastic wines Californis has ever seen."

California boosters, still eager that domestic wines be accorded the same respect as their European counterparts, are likely to use this vintage as evidence of how much progress has been made. It will be a year or more, however, before most whites reach retail stores and the slower maturing reds - cabernet sauvignon and pinot noir - are three years away.

In the meantime, the sky isn't totally cloudness.

Unless balanced by acid, highly sugared grapes can produce wines high in alcohol that taste, in the lingo of the trade, "fat" or "flabby." Most winemakers report high acids, but others acknowledge a fear that their whites may be unbalanced.

A strange sequence of weather conditions led to difficulties during the harvest. After two years of drought, there were heavy winter and spring rains. THe vines revived and an unusually hot summer caused grapes of all varieties to ripen at the same time. Uaually different varieties ripen in sequence and are processed in orderly fashion. This year, with so many ripe grapes, crushers and fermentation tanks at many vineyards were overtaxed. Ripe grapes had to wait. "Compromises," as one winemaker phrased it, had to be made. In the long run, quality may be affected.

The trade-strongly oriented to wine these days - has yet to absorb red wine from previous vintages. As the vats became full, the market price of cabernet sauvignon grapes tumbled dramatically. A financial crisis for growers was averted only when Gallo, the industry's largest winery, stepped in and bought before the price fell so low that some vineyards might have failed.

In the midst of all this activity, visits to 17 vineyards - spread over more than 400 miles, with productions ranging from Gallo's multi-million cases to Carneros Creek's 10,000 - left a vivid impression. Intelligent, articulate winemakers, many of them quite young, are pursuing similar goals in disparate fashion.

Almost everywhere are signs of the technological revolution that has changed winemaking techniques dramatically in the past two decades - including temperature-controlled, stainless steel tanks and the centriguge. The tanks monitor fermentations that once could run amok and spoil the wine, while the centrifuge is a filteringdevice that helps ensure clean, disease-free wines. This equipment is very expensive, though, so not every winery has as much of it as might be wanted.

Gallo's computer-equipped laboratory is a multi-million-dollar complex. More exologists (wine chemists) work there than at the University of California at Davia, the world's leading center for wine research. Yet despite the chemists' achievements, many winemakers feel, as Tony Austin of Firestone put it, "We should use the tools oftechnology judisciously." Francis Mahoney of tiny Carmeros Creek said flatly, "for $1,000 you can buy all the lab equipment you'll need, if your winery is clean and you do your housekeeping."

Throughout the process, judgments are made by that most imeract of scientific instruments, human taste buds. Winemaking remains more an art than a science and thereby retains an appealing degree of romance. Often the little guys outdo the big guys; new methods and new wineries produce astonishing results.

"If you're looking for proof that the romance of wine still exists," one vineyard owner said, "just watch how eager winemakers are at tastings - how fascinated they are with each other's products."

Now that the harvest is done, the industry will return to a number of long-range concerns.

Most experts feel the current oversupply of red wine is only temporary. They contend that a continued upswing in consumption the annual increase has been 10 percent of more over the past four years plus a progression by movie novice wine drinkers from white to red wines will solve the problem in the next few years.

Also, merchants draw a sharp distinction between wines produced from grapes grown in northern and coastal regions and those from the hot central valley. Grapes such as cabernet and chardommy are thought to develop their full character only in cool regions. But the wine boom led to plantings elsewhere. Demand for these reds is slack, but all the wines of prestige vineyards, whose grapes come from the north, are selling. "There is no excess of fine wine of any kind today," said J. Richard Sajbel of the Stanford Wine Company.

He and others in the trade say that white wine is in short supply and predict that the situation may worsen. In the short run, financially pressed or opportunistic vineyard owners may tear out red wine plantings or graft them over to white.

Quite a few vineries are plagued with a shortage of bottles, serious enough in some instances to restrict storage capacity and lead to forced over-aging of wines. These same wineries also struggle for recognition and shelf space in retail stores. Some have paid extremely high prices for prime grapes in hopes of making a wine that will win a gold medal and make the winery famous.

National distribution is desirable but difficult to achieve, as is [WORD ILLEGIBLE] of supply. A member of small wineries have bonded together to establich the Wine Service Co-op, a consolidation warehouse in the Napa Valley. From there orders filled by several of the wineries can be combined in a single shipment to the East.

There is talk about what action the federal government may take in several areas. Ingredient labeling from which wine is currently exempted is one; drawing from boundaries for growing areas (appellation of origin) is another. Action is desired to ease importation of American wines into Europe and Japan.

Last, but hardly least, is the struggle against continued inflation. Prices for wine at retail will go up. At Chateau St. Jean, one of the most influential of the new , small custom wineries, there was talk of a 10 percent rise for new releases. But the price increase for prestige European wines has been even more severe. "Thank God for the French," said one vineyard owner. "With the prices they are charging, they're our best friends."