Forecasters with the National Oceanic and Atmospheric Administration have upgraded their prediction for the global weather phenomenon known as El Niño, saying that all signs now suggest the pattern to be “significant and strengthening.”
In its latest monthly update, federal scientists say a consensus now unanimously favors a strong El Niño, pointing to higher-than-normal sea surface temperatures, weakening easterly winds, and other atmospheric factors as evidence for a strengthening prediction.
“What’s new this month is that we’re predicting this El Niño could be among the strongest El Niños in the historical record dating back to 1950,” said Mike Halpert, the deputy director of NOAA’s Climate Prediction Center.
NOAA forecasts a greater than 90 percent chance that the weather phenomenon will continue through the fall and an 85 percent chance it will last through the winter.
Halpert noted that surface temperatures in the eastern Pacific ocean near the equator are measuring 2 degrees Celsius above normal over the previous three months -- “a value that we’ve recorded only three times in the last 65 years.”
During the most recent of those times, the winter of 1997-98, Southern California saw double its usual amount of rain. Rivers throughout the state fattened to flood stages. Mudslides caused more than half a billion dollars in damage. And officials reported 17 storm related deaths.
Halpert says as of right now, the current El Niño isn't as strong as the '97 event at the same point in its development.
"In July and August of '97 was a stronger signal than what we're seeing now," Halpert said. "Right now, we're sitting behind '97."
More than rain, what matters to California water managers is the potential snowfall in the Sierra Nevada Mountains. That snowfall feeds reservoirs and rivers – the major sources of water for the state.
NOAA says a strong El Niño means the dice are loaded for heavy rains in the southern part of the state this winter. But what matters more is the potential snowfall in the Sierra Nevada Mountains, which feeds reservoirs and rivers.
The strong El Niño of 1997-98 yielded almost double the normal amount of snow. But this winter’s odds for Northern California snow remain murky – even according to NOAA’s consensus models.
“You see a very wide spread in those individual model results,” said Jeanine Jones, deputy drought manager for the Department of Water Resources That really conveys some of the uncertainty associated with making these forecasts.”
Federal forecasters are cautioning that while El Niño may result in a wetter-than-average winter, busting the drought would take more than that.
“We would need something on order with the wettest year on record to balance the four year deficit,” said Kevin Werner, who directs NOAA’s western regional climate services.
Right now, closing that deficit and ending the drought would require precipitation of two-and-half to three times above average, according to NOAA.
There’s also widespread debate over how El Niño will interact with a regional weather pattern nicknamed “The Blob,” a stretch of warmer than average water off the West Coast believed to be caused by a persistent ridge of high pressure that 's been deflecting storms away from California.
El Niño vs. "The Blob"
Predictions for an El Niño weather phenomenon collapsed around this time last year. Which is why Felicia Marcus, chair of the State Water Resources Control Board, says she’s not relying on hopes to undergird the state’s plans. “We got over hope as a strategy last year,” she says.
Marcus and her agency have limited water rights, demanded deep cutbacks in how people water their lawns, and funneled money to poor communities without reliable water supplies. She says none of that will change any time soon.
“What I’ve been saying is, it ain’t over till it’s over,” she said. Forecasters, too, are directing that message to drought-weary Californians.