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Why It’s Way Too Early to Worry About Rain Deficits in SoCal

Yes, it’s been pretty dry so far this winter, but there is no need to worry. The major winter storm that roared through Southern California Monday proved we can erase a month’s worth of rain deficit in one day. I recently explained how the climate where we live — the Mediterranean Climate — sees the majority of its annual rainfall in the winter months. In fact, a whopping 80% of Southern California’s annual rain and snow falls from December through March.

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Dry Start to California’s Water Year

A dry start to California’s water year is reflected in the season’s first snow survey of the Sierra Nevada snowpack. The statewide snowpack is 52% of average for Dec. 30. On average, the Sierra snowpack supplies about 30% of California’s water needs.

The California Department of Water Resources manual survey at Phillips Station recorded 30.5 inches of snow depth and a snow water equivalent of 10.5 inches, which is 93% of the January 1 average at that location, according to DWR officials. The snow water equivalent,or SWE, measures the amount of water contained in the snowpack and is a key component of DWR’s water supply forecast.

While the Phillips Station measurement was positive, DWR’s electronic readings from 130 stations placed throughout California show the statewide snowpack’s SWE is 5 inches, or 52% of the December 30 average.

“The snow survey results reflect California’s dry start to the water year and provide an important reminder that our state’s variable weather conditions are made more extreme by climate change,” said DWR Director Karla Nemeth. “We still have several months left to bring us up to average, but we should prepare now for extended dry conditions. The Department, along with other state agencies and local water districts, is prepared to support communities should conditions remain dry.”

Water supply diversity meets regional demand

“The first snowpack survey of the water year points to California’s climate variability, which is why a diverse water portfolio is needed to provide a reliable supply,” said Goldy Herbon, San Diego County Water Authority senior water resources specialist. “The Water Authority and its 24 member agencies have successfully diversified water sources, and continue to expand those sources, to ensure our supply meets the needs of the region’s 3.3 million people and its $245 billion economy.”

The supply sources include water from the Claude “Bud” Lewis Carlsbad Desalination Plant, where ten workers volunteered to live on-site in 2020 to keep the water flowing during the coronavirus pandemic.

Sierra Nevada Snowpack-Snow Water Content

Climate change brings less snow

When the Sierra Nevada snowpack melts, it feeds into rivers and is stored in reservoirs across California. Reservoirs are tapped as needed during the dry months. However, state officials again said that climate change is affecting California’s snowpack, as more precipitation falls as rain and less as snow. And they urged Californians to make water conservation a “way of life.”

“Today’s survey brought a first glimpse of how the state’s snowpack is shaping up, but there is a lot of winter still ahead,” said Sean de Guzman, chief of DWR’s Snow Surveys and Water Supply Forecasting Section. “While the dry conditions during late summer and fall have led to a below average snowpack, it is still encouraging to have the amount of snow we already have with two of the three typically wettest months still to come.”

DWR conducts five snow surveys at Phillips Station each winter near the first of each month, January through April and, if necessary, May. Guzman said the next survey is scheduled for February 2.

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Sean De Guzman (R), chief of the California Department of Water Resources Snow Surveys and Water Supply Forecasting Section, and Jeremy Hill, DWR water resources engineer, conduct the first snow survey of the 2021 season at Phillips Station in the Sierra Nevada. Photo: Kelly M. Grow/DWR

Utah’s Water Year So Far, and Why People Should ‘Think Snow’

So far this water year that began Oct. 1 has been treating most of Utah like a miserly scrooge, stingy with storms and the accompanying snow. The southern half of the state, as of Monday, was sitting in the 60% of normal accumulation of snowpack, and the Lower Sevier River Basin at 36% of normal is experiencing abysmally dry conditions.

La Niña and California’s New Water Year

It’s that time of the year in California, when water managers, climatologists and meteorologists look at the factors that determine what the winter will bring during Water Year 2020-21 (October 1, 2020 – September 30, 2021).

The National Oceanic and Atmospheric Administration recently said that La Niña conditions are present in the tropical Pacific, “with an approximately 85% chance of La Niña lasting through the winter.” Forecasters currently think this La Niña will be on the stronger side. For California, those conditions typically mean a drier winter, with increasingly dry conditions heading into 2021.

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La Niña and California’s New Water Year

It’s that time of the year in California, when water managers, climatologists and meteorologists look at the factors that determine what the winter will bring during Water Year 2020-21 (October 1, 2020 – September 30, 2021).

The National Oceanic and Atmospheric Administration recently said that La Niña conditions are present in the tropical Pacific, “with an approximately 85% chance of La Niña lasting through the winter.” Forecasters currently think this La Niña will be on the stronger side. For California, those conditions typically mean a drier winter, with increasingly dry conditions heading into 2021.

Fortunately for the San Diego region, any impacts from La Niña will be lessened because of the region’s development of a diversified water supply portfolio. Following a record number of acres burned from wildfires in 2020, La Niña would only increase fire danger.

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La Niña continues in the tropical Pacific, with an approximately 85% chance of lasting through the winter, according to NOAA’s October 2020 La Niña update. Graphic: NOAA

Water Year 2020

But, whether the forecasts come to fruition, and what that means for California’s water supply, won’t be fully known until next spring. What we know now is that the water year that just ended (October 1, 2019 – September 30, 2020) varied across the state.

While Northern California was mostly dry, parts of Southern California experienced above average precipitation, according to the California Department of Water Resources. The agency said that the water year ended below average and pointed to the impact of climate change on the California’s water supply.

Impacts of climate change

“California is experiencing the impacts of climate change with devastating wildfires, record temperatures, variability in precipitation, and a smaller snowpack,” said DWR Director Karla Nemeth. “We must continue to invest in our infrastructure to prepare the state to cope with more extreme weather for the state’s needs today and in the future.”

For Water Year 2020, a lack of precipitation resulted in a snowpack of just 50% of average on April 1, as measured by the California Cooperative Snow Survey Program, making it the 10th smallest snowpack in California since 1950, according to the DWR. California’s reservoirs received just a third of the water runoff from precipitation and snowmelt that they did during the same time period a year ago.

The wet season got off to a slow start, but a series of storms in late November and early December pushed 2019 precipitation to near or above average in central and southern California, according to Goldy Herbon, San Diego County Water Authority senior water resources specialist.

Driest February on record

“The wet start didn’t last with dry conditions taking hold over most of the state in January, and then most of California experienced its driest February on record,” said Herbon.

While precipitation picked up in March 2020 for Southern California, statewide snowpack in mid-March was only 38% of average.

“The dry north/wet south precipitation pattern continued in March and April, with some locations in Southern California setting many daily precipitation records, San Diego included, as northern California precipitation levels remained below average,” said Herbon.

Water supplies in “excellent shape”

Despite the below average year in northern California, Herbon said statewide water supplies are in “excellent shape” thanks to above average precipitation the previous year and good reservoir storage. DWR reports that statewide reservoir storage through the end of September 2020 was projected to be 93% of average.

In the San Diego region, a wet spring boosted rainfall totals to near or above normal.

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Regional precipitation during Water Year 2020. Graphic: National Weather Service San Diego

La Niña May Signal Scant Relief from California’s Seemingly Endless Loop of Hot, Dry Weather

After a brief interlude of mild temperatures Saturday, a warm-up is forecast to begin Sunday as upper-level high pressure builds into California, the National Weather Service said. High temperatures will climb by several degrees on Sunday.

Two Ways to Measure Annual Rainfall

Last Tuesday marked the end of the 2019 rain year, which runs from July 1 through June 30. Wednesday was the start of the 2020 rain year.

The 2018 rainfall season that occurred from July 1, 2018, through June 30, 2019, produced 15.68 inches of rain at the Santa Maria Public Airport, or about 121% of normal.

Snow-Water Equivalent Still Down Despite Recent Storms

Though the last couple of weekends have seen wet weather, it hasn’t been enough to keep up with the yearly average in time for summer in California. The Sierra Nevada snowpack, which is tested regularly by employees of the California Department of Water Resources, has yielded some grim results so far in 2020 in terms of snow-water equivalent.

After Last Week’s Storm, April is Already 3rd Wettest Month on Record

Although a mere 13 days old, this is the third-wettest April on record in San Diego, the National Weather Service reported Monday.

Potent Storm Bringing Heavy Mountain Snow, Flood Risk to California