A major pattern change is set to deliver California’s first atmospheric river of the season next week. Significant rain and snow is in the forecast for the Golden State, while damp, dreary days are ahead for other parts of the West as signs of El Niño’s influence on the upcoming winter season emerge.
Less than a year after facing historic water shortages, California this week was declared drought-free thanks to a year of epic rains, with an El Niño forecast that could keep wet conditions going into 2024.
For California, especially Southern California, El Niño can typically mean larger storms in the winter which can mean more rainfall and larger waves along the coast. Graphic: NOAA
As we get closer to winter, the phrase “atmospheric river” is more likely to pop up in headlines.
Here’s an explanation of what these phenomena are and how they impact weather in Northern California.
It’s still more than seven weeks before the official start of winter (Dec. 21), but weekend storms in Colorado’s high country are reason enough to look in on snowpack levels that will eventually provide the water that flows to Lake Mead.
A month into the 2023 “water year,” snowpack levels are slightly above normal in the Upper Colorado River Basin: 114% as of Nov. 1, according to data on the U.S. Bureau of Reclamation’s website. The water year runs from Oct. 1 to Sept. 30 each year.
The first measurable, widespread snow is expected in California’s Sierra Nevada Wednesday into Thursday, with a cold storm from the Gulf of Alaska poised to sweep the Golden State, according to the National Weather Service. There’s another chance for snow later in the week as well.
Every manifestation of the dangerous weather wreaking havoc around the world has one thing in common: water. As the Earth’s climate changes, the lack of water, or its sudden abundance, is reshaping the global economy and international trade. From prolonged drought slowing down ships in the Panama Canal to deluges halting industrial production in Japan, it’s one of the most obvious ways that rising temperatures are affecting businesses.
September was one of the warmest ever in the United States, with records falling in 111 counties, but conditions were moderate in Southern California.
Most of the country baked under record heat in September as large swaths of hot air covered the Midwest and East. The final tally put September 2023 as the seventh warmest in the last 129 years.
The National Oceanic and Atmospheric Association (NOAA) said it was also the third-driest September ever recorded in the lower 48 states.
After a summer of record-smashing heat, warming somehow got even worse in September as Earth set a new mark for how far above normal temperatures were, the European climate agency reported Thursday.
Last month’s average temperature was 0.93 degrees Celsius (1.7 degrees Fahrenheit) above the 1991-2020 average for September. That’s the warmest margin above average for a month in 83 years of records kept by the European Space Agency’s Copernicus Climate Change Service.
“It’s just mind-blowing really,” said Copernicus Director Carlo Buontempo. “Never seen anything like that in any month in our records.”
Current El Niño conditions appear likely to become comparable to the “great” El Niño of 1997-98, according to an experimental prediction system used by the National Science Foundation’s National Center for Atmospheric Research.
“Our forecast system has shown that it can do a remarkably good job of accurately hindcasting past El Niño events when we’ve tested it using historical data, which gives us high confidence in this forecast,” said NCAR scientist Stephen Yeager, who helped lead the modeling effort.
Thanks to a decades-long supply diversification strategy and continued efficient use of water across the region, the San Diego County Water Authority announced today that the region has reliable supplies to meet demands in Water Year 2024, which started Oct. 1.
Hydrologists use Oct. 1 to begin measuring the snow and rain that will help carry water users through dry summer months the following calendar year. This fall, El Niño conditions continue to strengthen and could bring above-average precipitation to Southern California.
The Water News Network is San Diego County’s source for water news and information.
