As an industry, wine goes through many stages where consumer buying patterns emerge to make some wines hot and others decline.

There was a time when chenin blanc was all the rage with Americans. It was light, slightly sweet, and refreshing. That was a legitimate trend that lasted for years, as did its replacement white wine, white zinfandel.

When the latter declined in sales, other white wines became popular, such as the last two decades of growth from pinot gris and pinot grigio. There was a brief recent flurry of activity with the rapid rise of Riesling sales, notably dry wines, but that has subsided in the last two years.

When sales of a particular wine jump unexpectedly, the industry's professional observers (marketing people, in the main) seek to determine if the frenetic activity is a trend or a fad. The latter is usually short-lived and after an explosive period, it fizzles. Trends stay around for a long while.

The rise in adventurous Millennial buyers has meant a lot of recent activity into diverse wines and most analysts are still trying to determine how long such fads will last, or if a trend is worth risking a sea change in a winery's direction.

Here are a few of my guesses:

Pinot gris: A trend. Every major wine company and most minor wineries now make a wine from this grape, and among the surprise leaders in quality is the once-small Russian River Valley-based J, whose PG has risen rapidly in volume. Oregon, which has had huge success with its pinot noirs, is now among the nation's leaders in pinot gris quality as well.

Moscato: A fad. This usually quite a sweet white (I have also seen pink and even red versions!), isn't a "serious" wine, and the latest hot demand for it seems to be coming from the non-wine-drinking side of the ledger. A few hip-hop performers have mentioned Moscato in lyrics, and that was all it took for the wine to take off.

Red wine blends: Trend. With syrah sales stuck in the mud, wineries have found a partial solution: make a red wine blend using syrah. Millennials seem smitten with this "no-brainer" red wine because you don't have to know what it is supposed to smell or taste like.

"As long as it's reasonably priced," one retailer told me, "they'll take it, and only about 20% of my buyers even care what's in the wine."

Sweet red wines. A fad. Some of these wines are actually cloying and so soft that they make real wine lovers gag. They may continue to be made, and may sell to the non-wine crowd, but Millennials seem to dislike the wines.

Sherry and Port. A Trend. Moribund for decades, these fortified wines are coming back, albeit slowly. Younger buyers are rediscovering these wines that often are used in after-dinner dessert-pairing. But one retailer said he has also seen more interest in dry Sherries lately and hopes younger buyers see how wonderful they are paired with rich soups.

Sparkling wines: A trend. Although true Champagne is pricey and still sells mainly as a celebratory wine, the entire sparkling category is on the rise. A major part of this is interest in Italy's Prosecco, a lower priced alternative. And even though a Prosecco may use the hard-to-pronounce designator Valdobbiadene Superiore, it is selling. Latest figures show Prosecco sales this year are 27% higher than a year ago.

Wine of the Week: 2012 Husch Chenin Blanc, Mendocino ($10) — The aroma of melons, Asian pears, and a faint blossom-y note are so appealing that I'm shocked this wine is so reasonably priced. Yes, it's got a trace of residual sugar, but it has excellent acidity so the wine isn't very sweet and actually works nicely with spiced Asian foods.

<i>Sonoma County resident Dan Berger publishes "Vintage Experiences," a weekly wine newsletter. Write to him at winenut@gmail.com.</i>