CLOVERDALE, Calif. -- Amid the ocean of California chardonnay and West Coast pinot noir that inevitably floods the world's largest competition for American wines, there are always some telling surprises. A serious port-style wine from South Jersey? An evocative rosé from sunny Kennett Square? A deep, plush, and spicy petit verdot from the verdant vineyards of Fort Washington?

Uh-huh. It happened. I was there. And as one of the 62 judges who put on a lab coat for four days to sip, swish, and spit our way through the blind tasting of 7,000 mystery wines at the 17th annual San Francisco Chronicle Wine Competition in this northern Sonoma agricultural town, I can tell you the proof is always inside the glass. And the delight is in the surprise of the big reveals at the end, when the identities are finally made known, and some trend-spotting can begin.

Red blends were up big, 20 percent over last year. Rosé and riesling entries continued to climb, as did Italian varietals like sangiovese and barbera  -- though to mixed success as producers are still striving to find ripe New World expressions for Old World red grapes that depend on firm acidity for character. The sweet spot for chardonnay seems to be around $30-$35, where the fruit is still high quality but winemakers don't overcompensate with too much oak to justify a $50 price tag. And, most encouragingly in a big competition like this, where wines are submitted from 28 states, the existence of good winemaking in virtually every corner of the country is put on display.

Yes, the overall best-in-show "Sweepstakes" winners reaffirmed California's sustained dominance: The top red was a 2013 old-vine zinfandel from Tonti in Russian River; a 2015 Anderson Valley gewürztraminer from Castello di Amorosa that  my panel picked tied with a racy 2016 sauvignon blanc from Hanna for best white. But there were also strong showings from many other states, including several participants from the Mid-Atlantic. Three local wineries, from the Philadelphia suburbs and South Jersey's Outer Coastal Plain AVA, earned gold awards for select wines, a distinction given to only 14 percent to 18 percent of entries.

Sharrott Winery from Blue Anchor in Winslow Township earned a rare "double gold" (signifying consensus among its judging panel) for its port-style wine, Wicked, made from chambourcin. Galer Estate Vineyard in Kennett Square near Longwood Gardens won gold for its rosé of pinot noir. And Fort Washington's Karamoor Estate won gold for its petit verdot.

"That's why I enter these major national and international competitions," says Larry Sharrott Sr., who has won gold before in the Chronicle competition with his barrel reserve chardonnay (silver this year), cab franc, and merlot. "I want to validate my wines against the best wines in the country. That's what we're shooting for. Not just the best Jersey wine -- the best wines period."

Of course, Wicked also won the Garden State's Governor's Cup in 2015 for top sweet wine, so that best-in-Jersey box has already been checked. But local winemakers say there can never be too much validation from national benchmarks to aid their daunting quest to persuade a skeptical audience that quality wine can be made in our backyard.

"The West Coast competitions have served us well as a Pennsylvania winery trying to get noticed," says Ali Duloc, director of sales and marketing at Karamoor Estate Wines, the 27-acre Fort Washington vineyard and winery owned by her grandparents Athena and Nick Karabots. "If we can do well there, it gives us a little more confidence in talking to our customers about Pennsylvania wines."

Karamoor also won a silver this year for its merlot-based 2013 meritage blend. But its gold-medal success with a 100 percent petit verdot from the 2013 vintage offers an especially intriguing detail --  new hope for an underutilized red grape that's now proven to grow with ripeness and complexity in the Mid-Atlantic's finicky climate. In recent years, cabernet franc has shown itself convincingly to be the region's most promising red. But a silver medal this year also for Sharrott's 2013 petit verdot, slightly leaner than Karamoor's, but also plush with dark fruit and brambly spice, bolsters the case for winemakers to  give more consideration to the inky black grape, prized mostly in Bordeaux as a blender for color and structure. And the "PV" surge isn't just regional. Robert Fraser, director of the Chronicle's wine competition, says petit verdot entries increased by 20 percent this year, especially as wineries work to expand portfolios for direct-to-consumer wine clubs, where the more experimental bottles tend to flow.

As for chambourcin, a French American hybrid that's long been popular with local winemakers, I think Sharrott's port-style ruby sweet fortified with brandy may be one of the better uses I've tasted for the grape, which can often turn musky (or foxy) on the finish when made as a dry still wine.

Meanwhile, Galer's rosé made from Chadds Ford pinot noir showed a resourceful approach to a prestigious grape that winemakers covet but that many also struggle to produce consistently due to its temperamental nature and thin skin. Galer's young winemaker, Virginia Mitchell, says that targeting pinot for rosé, which allows for an earlier harvest when the fruit is slightly less fragile, is a consistent way to go. The Kennett Square winery owned by Lele and Brad Galer in the shadow of Longwood Gardens has a history of good rosés (I featured a blend in 2013), and this one, full of bright raspberry-cherry notes with a squirt of natural residual sweetness, is proof the approach is sound. Galer's juicy Red Lion vineyard chardonnay, fermented in stainless steel, took home a silver.

Two other local wineries, both in South Jersey's Outer Coastal Plain, also took silver awards. Bellview in Buena won for a red blend (Capella) and a white blend (Cygnus). Heritage Vineyards in Mullica Hill won for a white blend of muscat, albariño, and chenin blanc. Three other wineries elsewhere in New Jersey -- Sky Acres, 4JG's, and Unionville -- also won gold.

Though many local wines have now established a more consistent track record for quality, the issue of high prices due to relatively small production may remain a major hurdle to convert the reluctant. The marketplace, however, is deciding differently. Galer's prize-winning rosé? It sells for $30. Karamoor's petit verdot? A whopping $55, considerably more than the mid-$30 range for the rest of its wines.

"We grow all our own grapes and have extremely limited production, with only 300 bottles of this wine," says Karamoor's Duloc. "And we don't make it every year -- only when we have superlative grapes, as with 2013 and 2014. In 2015, we didn't do it. So that's where supply and demand comes into play. We'd rather let a little of it hang around and improve with age on our shelves than price it at $25 and sell out in a month."

Likewise for Galer's pinot rosé, which sold out in three weeks at $21 for its first vintage in 2014, and lasted only just a little longer with the prize-winning version from 2015 that, at $30, sold out in December. The best thing about our local wine industry, however, is that there's always another vintage for those wines, and winemakers mature and improve. "The 2016 rosé," says Mitchell, "will be ready by spring."