The weak-to-moderate El Ni-o affecting weather in the Sierra Nevada this year is expected to continue to bring above-average amounts of moisture to the region through March, a climate expert says.
El Ni-o describes the warming of thousands of miles of ocean off the coast of South America. The warmer waters influence the global climate, causing relatively dry places to get more moisture and wet places to get less.
Climatologists are predicting a 40 percent chance that a large number of storms will continue to roll through the region. But they say they have no way to determine if the storms will drop enough moisture to pull the area out of the drought it's been in during the last three years.
La Ni-a, the term used when ocean temperatures in the Pacific are colder than normal, put the Northern Sierra in a drought, said Edward O'Lenic, chief of climate operations at the National Oceanic and Atmospheric Administration.
O'Lenic spoke Tuesday at Operation Sierra Storm, an annual weather conference held at the Resort at Squaw Creek.
He said there have been 12 El Ni-o patterns in the last 50 years. A British climatologist named Sir Gilbert Walker, who crunched global weather data for a living, was the first scientist to document what became known as El Ni-o.
Walker made the discovery around 1920 but the phenomenon has existed for thousands of years.
"El Ni-o tends to last on the order of a year," O'Lenic said. "Occasionally it will last two years running. No one really knows why El Nino persists."
O' Lenic said his staff of climatologists probably will make predictions for next winter in May.
"We're still in the discovery phase in El Ni-o," O'Lenic said. "We're being taught humbling lessons by nature."
In the Sierra, a winter season affected by El Ni-o tends to be a warmer one, said O' Lenic, but they can also end up being drier than normal seasons.
"But there's a higher probability it will be wet," he said.
The last El Ni-o to affect the Sierra came in the winter of 1997-98. It was much more powerful than this El Ni-o.
The meteorological phenomenon led to a 100-year flood on New Year's Eve after rain melted a deep snowpack. Homes at the Tahoe Keys got the worst of the flood.