The chances of an El Niño that would help relieve a drought-wary California this fall or winter have fallen for a second straight month, to just 60-65%, according to the National Oceanic and Atmospheric Administration (NOOA). In May, forecasters had put the chance of an El Niño occurring at 80%.
Even more disappointing is that forecasters believe the El Niño will be weaker than expected, not nearly enough to pull California out of one of the worst droughts the state has ever experienced.
According to the San Francisco Chronicle, El Niños in the past have correlated with particularly rainy winters in California. In 1997-98, an El Nino helped produce San Francisco’s wettest year ever, with 47.2 inches of rain.
Despite the decreased chances for an El Niño, Climate Prediction Center acting director Mike Halpert told the Chronicle that there are other factors that could determine how wet California’s fall and winter will be.
“Every El Niño is different,” Halpert said. “A weaker El Niño or even no El Niño doesn’t necessarily mean it’s going to be dry in Northern California. If El Niño doesn’t develop, this winter will be dominated by some other pattern that we don’t yet know about. It could certainly be a pattern that is wet.”
Still, the chances of an El Nino are, for the moment, in California’s favor.
“The weekly Niño-3.4 index has increased over the last three weeks, from 0.0C to 0.3C to 0.4C,” National Weather Service climate analyst Michelle L’Heureux told the Washington Post. “Thus, the Pacific is nearing the cusp of meeting El Niño criteria which requires the index to warm to 0.5C, remain at that level for at least one month, and be complemented by an El Niño signal in the atmosphere.”
“We’re not favoring dry,” Mike Halpert told the Chronicle. “Maybe that’s a good thing, but we’re also not favoring wet. Everything is fair game.”