Farmers were scurrying to complete field work and harvest activities before a monster storm bore down on the West Coast late Tuesday, Nov. 19, bringing massive amounts of rain and snow that could get this winter’s snowpack and reservoir levels off to a fast start.

In Northern California, crews rushed to finish orchard sanitation and winter pruning knowing it was “all going to come to a screeching halt” when the storm arrived, said Colleen Cecil, executive director of the Butte County Farm Bureau.

“For tree nuts and rice, and for beef cattle like we’ve got in Butte County, everyone’s preparing for the rain and trying to get done what we can,” said Cecil, whose family grows walnuts in Glenn County.

University of California Cooperative Extension orchard systems adviser Luke Milliron was racing to finish some replants in a trial orchard in the hours before the storm.

“If people are anything like myself, they’re scurrying around trying to do all the field work we can ahead of this monsoon,” Milliron said Tuesday afternoon.

Some walnut and citrus growers were also running wind machines and irrigation in response to several nights of freezing temperatures before the big storm arrived.

“With these cold temperatures in November, we don’t see the damage until harvest,” Cecil said.

Related:La Nina to return by late summer

All the activities came before what was expected to be by far the biggest storm to hit the West so far in the water year that started Oct. 1. So far, the storm has knocked out power for nearly 130,000 customers in the Pacific Northwest and California, brought hurricane-force winds to the Oregon Coast, downed trees and prompted numerous flood warnings throughout the region, according to The Associated Press.

Series of storms

The storm – which meteorologists say is a combination of an atmospheric river and bomb cyclone – is the first of a wave of heavy rain and snow events that could continue through Thanksgiving, the National Weather Service warns.

“We’re looking at prolonged periods of rain, mountain snow and rising snow levels,” Sara Purdue, an NWS meteorologist in Sacramento, said in a video presentation. She warned of rapidly rising streams in the first wave, which could continue into Saturday. The next wave late Saturday through Nov. 26 should bring less rain to lower elevations but dump several feet of snow at mountain passes, she said.

“We'll be seeing sharp rises on area waterways, and areas that haven't been flowing since before this summer will start flowing again,” she said. In addition, “there is some potential for wet weather to continue into the Thanksgiving holiday period,” she added.

The harsh weather could pause a multitude of winter harvests in California, from Central Coast lettuce and berries to San Joaquin Valley oranges and late-variety table grapes. The California Olive Ranch, which owns or contracts with oil-olive acreage from Red Bluff to Bakersfield, had already recorded an average of 1.9 inches of rain at its ranches as of mid-afternoon Wednesday, Nov. 20, senior grower relations manager Brittany Fagundes said.

Before the rain arrived, the company prioritized its harvests for ground that would be the most difficult to get equipment into when the rain stopped, Fagundes said.

“When red dirt gets wet, it really doesn’t have a bottom,” she said. “Most of our other ranches up north are on old rice fields that can take about 10 inches of rain. And we have a bunch of grower acres down south that don’t have as much rain.”

This year’s harvest is about 80% complete, she said.

“A couple of years ago we got 7 inches of rain in the second week of harvest, and that was pretty rough,” Fagundes said. “We usually plan on wrapping up harvest around Thanksgiving. This will push that back into early December.”

La Nina winter

This week’s storms are nature’s first major salvo in what is forecast to be a weak La Nina winter, with wetter-than-average conditions in the Pacific Northwest and drier-than-average conditions in the U.S. Southwest through March, according to the federal Climate Prediction Center.

A series of small storms have been spritzing the West Coast in the past couple of weeks, causing only minor disruptions in agriculture. In California, according to the National Agricultural Statistics Service:

The arrival of bigger storms will help reservoir levels that have so far been lagging behind last year’s levels. As of Nov. 18, Shasta Lake, the centerpiece of the federal Central Valley Project, was at 55% of capacity, down from 68% from the same date last year. Lake Oroville, the State Water Project’s main reservoir, was at 47% capacity Nov. 18, down from 66% a year earlier.

The storms will also aid snowpack levels, which were near normal in California as of Nov. 20. However, state Department of Water Resources spokesman Jason Ince cautions that snow accumulation in the fall isn’t usually indicative of where it will end up in the spring. The DWR will begin its regular manual snow surveys around Jan. 1.