Christian Moueix is the kind of man who has annual rainfall statistics memorized. “In Bordeaux, the average is 38 inches, with much less variation than Napa,” he detailed. “The past 25 years in Napa range from 8 to 63 inches.” It’s important for vintners—and not just Moueix, whose 134-acre Napa Valley property Napanook Vineyard is dry farmed—to keep track of rain because early precipitation can set the stage for an excellent vintage. At the same time, too much rain can have negative consequences. “Vintages with heavy rain, above 50 inches, were 2011, 2017 and 2019,” Moueix said. “What does that mean? Vegetation is so strong that even if we reach full ripeness, there is still some herbal character.”
California’s three weeks of storms dumped a tremendous amount of rain on the state. While the weather led to at least 22 deaths and scores of washed-out roads, mudslides and flooded neighborhoods, many farmers couldn’t help but welcome the wet weather after years of being strapped for water resources. Many areas have already attained their average rainfall for the entire year. As a result, aquifers are recharged and reservoirs are full.
And for the state as a whole, according to the California Department of Water Resources, the snowpack in the Sierra Nevada mountain range currently holds more than twice the water content than in an average year. Melt from the snowpack provides approximately 30 percent of the water supply to the state each year.
The series of atmospheric rivers that carried warm moisture from the Pacific to the West Coast shifted with each storm, ensuring that almost every part of the state saw heavy rainfall at some point. Most parts of Napa and Sonoma experienced more than 25 inches of rain. Paso Robles rainfall estimates were around 20 inches. But rainfall also varied within each appellation—the western part of Sonoma’s Russian River Valley usually gets more rain than the Alexander Valley, and that was the case during these storms.
The season’s rain has brought much of the state out of severe drought risk but, as a whole, California remains moderately or abnormally dry. “We’ll take all the rain we can get,” said Hanzell president and director of winemaking Jason Jardine. “A rainy day is never a disappointing day!”
Harnessing the rain
Of course, rain has to fall at the right time for vintners. Winter months are the best time for rain in the vineyard. The grapevines are dormant up until budbreak. And a big drink, thanks to Mother Nature, helps fill reservoirs and ponds, allowing vintners to use water at will for frost protection or irrigation throughout the season. On the other hand, too much rain, in rare cases where vineyards become flooded for extended periods, can waterlog vines and prevent oxygen from reaching the roots, impeding the vines from gathering water and nutrients.
How vintners use the rain depends a lot on their specific approach in the vineyards. At Hanzell in Sonoma, Jardine farms biodynamically, and early rains in October and November helped establish cover crops, which are now flourishing thanks to the rain in December and January. Moisture also activates microorganisms, which help break down organic matter and liberate minerals for the vines.
Erosion is a big concern for Jardine because of Hanzell’s hillside vineyards. Erosion can wash away those key minerals and nutrients. Many growers combat the problem with hay bales, but cover crops, grasses and herbs planted between the rows, can also prevent soil from washing away. They also help vintners control moisture levels year round.
Jardine uses cover crops and a no-till strategy to create a sponge layer to soak up the rain. Later in the season, he crimps cover crops to avoid disrupting topsoil. That layer then acts as a buffer against the sun, aiding in retaining moisture in the soil for extended periods. This also keeps the soil temperatures cooler, which can, depending on the subsequent weather…
Source : https://www.winespectator.com/articles/did-the-pineapple-express-end-californias-drought