(NBBJ) - Suspicions in the industry that the 2013 North Coast winegrape crop would be sizable are gaining greater weight as many of the grapes for sparkling wine are past that early round of harvest are in the winery, picking white wine grapes is under way and the first red wine grapes are approaching ripeness.

“Generally, with what we’ve seen of the crop so far, I think it will be a big crop,” said Glenn Proctor, partner of Ciatti Co., a San Rafael-based major broker of grapes, wine and concentrate. One local sparkling-wine house just finished with harvest told him early last week that vineyard yield was “above average,” and another told him tonnage was up to 10 percent above the winery’s estimates. Yet without knowing if the estimate was too high, low, readjusted repeatedly or in line with local averages, such statements can be hard to evaluate, he said.

Picking of grapes at lower sugar levels for sparkling wine started in late July in Napa County and early August in Sonoma County. Napa Valley pinot noir had above-average tonnage, and the North Coast crop overall is looking sizable, according to Novato-based Turrentine Brokerage.

Three-quarters of the sauvignon blanc crop had been picked by last week, with above-average tonnage from Napa and Lake counties and average to above average from Sonoma County, according to Turrentine.