Winemaker Kevin Morrisey looks over his daughter Oona, right, picking Sauvignon Blanc grapes by headlamp at Ehlers Estate winery Wednesday morning, Aug. 28, 2013 in St. Helena, Calif. Harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )
A load of Sauvignon Blanc grapes are dropped into a bin during harvest at Ehlers Estate winery Wednesday morning, Aug. 28, 2013 in St. Helena, Calif. The harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )
Workers sharpen their knives and rest while waiting to unload their bins of Sauvignon Blanc grapes during harvest at Ehlers Estate winery Wednesday morning, Aug. 28, 2013 in St. Helena, Calif. The harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )
Workers harvest Sauvignon Blanc grapes by headlamp at Ehlers Estate winery Wednesday morning, Aug. 28, 2013 in St. Helena, Calif. The harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )
Alfredo Lopez, right, sorts Sauvignon Blanc grapes after they were picked at Ehlers Estate winery Wednesday morning, Aug. 28, 2013 in St. Helena, Calif. Harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )
The sun is filtered through the fog in the Stelling Vineyard at Far Niente winery Wednesday, Aug. 28, 2013 in Oakville, Calif. Harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( APTOPIX Napa Wine Harvest )
Chardonnay grapes are picked in the Stelling Vineyard at Far Niente winery Wednesday morning, Aug. 28, 2013 in Oakville, Calif. Harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )
Workers carry bins of Chardonnay grapes to a tractor during harvest in the Stelling Vineyard at Far Niente winery Wednesday morning, Aug. 28, 2013 in Oakville, Calif. The harvest is underway in the Napa Valley with the picking of grapes for white and sparkling wine. (AP Photo/Eric Risberg) ( Napa Valley Wine Harvest )