While California will not receive a soaking rain similar to what occurred at the beginning of the week, residents across the state can expect unsettled weather to stick around through Wednesday.
More rain and mountain snow will move through the West, including communities in worsening drought, in the early part of the week ahead. This wet pattern began when an area of low pressure moved into the California coast on Sunday. It brought more than an inch of rain to much of the Los Angeles area.
In the rolling hills of Fallbrook, California, Joseph Rossi and his family have been growing avocados at Rossi Ranch for 23 years.
The fruit has become so popular they now rely on their farm alone to make a living.
“It’s 100 percent of our income for the past seven years now,” Rossi said.
February has been amazingly dry in California, if anyone hasn’t noticed. No precipitation at all in February, a dry forecast, about 51% of seasonal Sacramento Valley precipitation (a bit less for the San Joaquin and Tulare basins), and only about half (45-57%) of normal snowpack for this time of year. Unless March is wet, this dry year seems likely to advance the onset of the fire season and threaten forest health this year.
Reservoir levels are still not bad for this time of year. Many are fuller than average, perhaps reflecting some snowpack loss. Some other reservoirs are a bit low. This is inherent in the first year of a drought, low precipitation and snowpack, but mostly ok reservoirs.
Groundwater has recovered somewhat from the previous 2012-2016 drought, better in the north, but less in the state’s more overdraft-prone areas in the San Joaquin and Tulare basins.
Scientists have documented how climate change is sapping the Colorado River, and new research shows the river is so sensitive to warming that it could lose about one-fourth of its flow by 2050 as temperatures continue to climb. Scientists with the U.S. Geological Survey found that the loss of snowpack due to higher temperatures plays a major role in driving the trend of the river’s dwindling flow. They estimated that warmer temperatures were behind about half of the 16% decline in the river’s flow during the stretch of drought years from 2000-2017, a drop that has forced Western states to adopt plans to boost the Colorado’s water-starved reservoirs.
The snowpack in the Rocky Mountains is currently 14 percent above average for this time of year, but last year’s dry summer could reduce runoff to the Colorado River.
All of those dry January days have taken a toll on California’s snowpack, but officials say it’s too early to worry about drought conditions.
Surveyors with the California Department of Water Resources trekked through a snow-covered field Thursday at the department’s Phillips station, above Lake Tahoe, to take the second seasonal measurement that serves as an important marker for the state’s water supply.
Last month, the state’s snow survey team saw snow levels just shy of average and on Thursday the trend continued downward.
“Seventy-nine percent of an average February and 58% of the April 1 average here at this location,” said Sean de Guzman, chief of the Department of Water Resources’ Snow Surveys and Water Supply Forecasting Section.
Along with measurements taken at the station near Echo Summit, measurements at 260 other locations indicate the snowpack is below average.
The California Department of Water Resources announced Friday an increase in 2020 State Water Project allocations to 15 percent of requested supplies, up from the year’s initial 10 percent allocation announced on Dec. 2.
Allocations are reviewed monthly based on snowpack and runoff information and are typically finalized by May, according to DWR officials.
As the world warms and precipitation that would have generated snowpack instead creates rain, the western U.S. could see larger floods, according to new Stanford research. An analysis of over 400 watersheds from 1980 to 2016 shows that winter floods driven by rainfall can be more than 2.5 times as large as those driven by snowmelt. The researchers also found that flood sizes increase exponentially as a higher fraction of precipitation falls as rain, meaning the size of floods increased at a faster rate than the increase in rain.
The Water News Network is San Diego County’s source for water news and information.
