Months ago, climate experts anticipated that one of the strongest El Niños on record would bring torrential rainfall to California, potentially leading to an end to the state’s crippling five-year drought. Instead, precipitation has been below average in Southern California and only average in Northern California.
Weather forecasters and millions of Californians welcomed the start of the 2015-2016 rainfall season with preparations for what was supposed to be an epic year of heavy precipitation, mudslides and drought-busting mountain snowpack. Climate scientists were pointing to the development of one of the strongest El Niño events on record, which seemed poised to send moisture-laden storms to the drought-stricken Golden State.
Yet as spring begins, Southern California is far behind average rainfall, a victim of an unforeseen massive ridge of high pressure similar to the one that has steered winter storms to the north in recent years. Northern California is doing better, with the best snowpack in five years, yet precipitation totals there are still no more than average.
Why Did Forecasters Predict Heavy Rain?
As most California residents know, El Niño refers to the periodic warming of the tropical Pacific Ocean off the coast of South America. This phenomenon occurs every two to seven years, while major El Niños, such as the current event, occur every few decades.
There is little historical relationship between weak to moderate El Niños and California rainfall, with some years witnessing historic flooding, while others years seeing average rainfall or even exacerbating drought conditions. But El Niños with sea temperatures warming more than 2°C, such as the current event, tend to bring heavy rain and snow to California and the Southwest U.S., as changes in the jet stream that controls the flow of winter storms favor the region. This occurred during the El Niños of 1982-1983 and 1997-1998, which both resulted in historic rainfall over the Golden State.
No Relief for California’s Drought
California’s current drought began in 2011, following two years of average rainfall. The last truly wet year was back in 2005. Historical records show that Southern California has not had a fourth season of drought since the 1800s. “We have never before had four consecutive years of drought in this part of the world, at least in modern times. Based on that, my gut is telling me it is going to be a wet one,” John Lindsey, a former U.S. Navy meteorologist, told the Santa Barbara Independent back in November. “I mean, if we do have a fifth year, it will signal a fundamental paradigm change. All the rules about what is possible and what is impossible would have to be rewritten.”
Yet the unprecedented appears to be happening, as rainfall has been meager for the Southland all season long, and the entire state has suffered through an almost rainless and abnormally warm February. March appears to be the state’s last chance for heavy rainfall, based on the region’s climate. El Niño tends to favor heavy rainfall through late spring, and storms could occur in April or even May, but rain and snow totals during those months would probably be insufficient to cause significant drought relief.
Orange County Impact
In Santa Ana, Orange County’s largest city and county seat, the average annual rainfall since 1906 has been 13.69 inches.
During the 1997-1998 El Niño, 30.88 inches of rain fell. The 1982-1983 episode brought 24.80 inches.
Following are the rainfall totals for each year since the drought began:
2011-2012 9.89 inches
2012-2013 4.74 inches
2013-2014 3.58 inches
2014-2015 6.63 inches
2015-2016 5.39 inches
SOURCE: http://www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca7888; seasons are calculated from July 1 to June 30 each year, inclusive; 2015-2016 data as of 10 a.m. on March 7
What Can We Expect After El Niño?
Unless a miraculously wet spring refreshes California, there is bad news ahead for the state’s water supplies. La Niña, El Niño’s sister, is likely to strike, potentially worsening drought conditions for years to come.
La Niña, also known as El Viejo, refers to the periodic cooling of the tropical Pacific Ocean. These events tend to occur after major El Niños and can last for years. Often the impacts of La Niña events continue until the next El Niño. The current California drought really kicked in during the La Niña at the start of the decade, for example.
For the United States, La Niña may actually be more significant than El Niño. La Niña tends to cause drought, not only in California, but also in the Midwest U.S., which is one of the world’s chief crop-producing regions. It also diminishes the wind shear that can destroy hurricanes and tropical storms; so, devastating hurricane landfalls are more likely during La Niña years. Finally, severe tornadoes in the Midwest seem to be more common during La Niñas.
Since California is already in unprecedented drought, climate scientists assume that the La Niña that might develop later this year would continue below-average rainfall and quickly reverse any water supply gains that the current El Niño provides.
Why is California’s Unprecedented Drought Happening to Begin With?
California’s climate is prone to periodic droughts, followed by unusually wet years. Yet the current drought has been unprecedented for its duration and severity and no one is certain when – or if – it will end.
As is true of the United States generally, California has a short historical record, as large populations did not inhabit the state until the 1800s. Yet tree ring records, historical lake levels and other natural indicators provide some evidence of what the climate was like in centuries and millennia past. These records seem to show that megadroughts lasting for decades occurred in the western U.S. before Europeans arrived. It is possible that such a drought is occurring again.
It should be noted that during a megadrought, there could still be some wet years, but the overall pattern would be dry. Beginning in the 1990s, much of Australia was in drought until 2012 (known as the Millennium Drought), which had a very negative impact on farming communities in the interior of the vast southern continent.
Climate change may also be playing a role. While earth’s climate is very complex and scientists have much to learn, there is general agreement that the planet is warming rapidly, which is causing more heat waves, melting snowpacks and rises in sea level. These conditions are unprecedented for the era in which humans have lived on planet earth. The abnormally high temperatures that have accompanied California’s drought are likely due at least in part to these broader changes. Some scientists fear that warmer temperatures could combine with a stronger ridge of high pressure to throw the southwest U.S. into a state of permanent drought.
What Will the Economic Impacts Be?
California is the nation’s leading crop-producing state and agriculture has been hard-hit by the drought. These impacts are likely to worsen if the drought persists.
“The economic impact of the current drought can only be approximated and is expected to be about $2 billion loss in output and 17,000 lost jobs, primarily in agriculture in the Central Valley, according to current estimates,” reported Mihaylo Dean Anil Puri and Economics Professor Mira Farka in their spring 2015 Midyear Economic Forecast.
Future impacts will likely depend on whether the drought continues and the state’s success at developing alternative water supplies.