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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

Surprise Finding: Calif. Drought Vulnerability ‘Very Low’

California is one of the least vulnerable states to drought even as it faces record wildfires, according to a first-ever state ranking funded by NOAA. The “Drought Vulnerability Index” finds that Oklahoma is the most susceptible to extreme dryness followed by two other states — Montana and Iowa — with a “very high” drought vulnerability.

Experts Say Drought, Wildfire Risk to Persist Across Much of US This Fall

As historic wildfires continue to burn across California, Oregon and other Western states, government climate experts say much of the U.S. is likely to see persistent drought conditions and fire risk alongside continued above-average temperatures through the fall.

During a briefing Thursday, forecasters with the National Oceanic and Atmospheric Administration said that while wetter conditions are expected to bring some drought relief to parts of the Pacific Northwest and New England in the months ahead, drought conditions are likely to persist or even worsen in Central and Southern California and across the Southwest.

Northern Hemisphere had its Warmest Summer Ever, NOAA says

The Northern Hemisphere had its hottest summer on record in 2020, the National Oceanic and Atmospheric Administration said Monday. Scientists from NOAA also said that 2020 is likely to be one of the five warmest years on record, and that last month was the second-warmest August on record.

NOAA said the 10 warmest Augusts have all occurred since 1998 and the five warmest Augusts have occurred since 2015. North America had its warmest August on record, with a temperature departure from average of +2.74 degrees Fahrenheit, according to NOAA.

La Niña May Worsen Southwest Drought This Winter

Climate forecasters said Thursday that the world had entered La Niña, the opposite phase of the climate pattern that also brings El Niño and affects weather across the globe. Among other impacts, La Niña has the potential this winter to worsen what are already severe drought conditions in the American Southwest.

How Record-Smashing Heat Invited Infernos to the West

Two weeks ago, the Pine Gulch Fire became the largest wildfire in Colorado history when it grew to an area nearly the size of Chicago. The 139,000-acre blaze, ignited July 31, was fueled by another record: The area where the fire occurred experienced its hottest August in at least 126 years.

Meteorologists Forecast Drought-Producing La Niña Weather Pattern this Winter

Federal weather forecasters on Thursday predicted the development of drought-producing La Niña pattern that could to last through the winter.

There is a 60% chance that La Niña will develop during the Northern Hemisphere fall, with a 55% chance the pattern will continue through the winter of 2020-21, the National Weather Service’s Climate Prediction Center said in its monthly forecast.

Escondido Creek Conservancy Receives NOAA Grant for Environmental Education

Funds to support 3rd grade students in the Escondido Union School District have been awarded to The Escondido Creek Conservancy.

The Conservancy has been awarded a national grant from the National Oceanic and Atmospheric Administration Planet Stewards Education Project to fund environmental education and stewardship in Escondido. The program will support 3rd grade students in the Escondido Union School District as they work to address the problem of litter in their community, in conjunction with their learning about local habitats and the impacts of humans on the environment.

NOAA’s La Niña Watch Could Signal a Dry Winter for Los Angeles

The National Oceanic and Atmospheric Administration issued a La Niña watch earlier this month, meaning that conditions are favorable for development of a La Niña in the next six months.

Major Ocean Research Effort Centered in San Diego

The Scripps Institution of Oceanography in San Diego will host a major research initiative funded by the federal government.

UC San Diego will host the Cooperative Institute for Marine, Earth and Atmospheric systems, and it will get up to $220 million in funding for research over a five-year period.

The National Oceanic and Atmospheric Administration is making the investment locally after a competitive bidding process.