El Niño brewing in Pacific likely bringing wet winter
July 10, 2009
 |
| Soaked: A powerful El Niño in late 1997 and early 1998 dropped heavy rain on the Bay Area, with 47 inches falling in San Francisco and flooding in Petaluma, above. (AFP/Getty Images) |
SAN FRANCISCO — If you like to bet, you might want to put your money on an extra umbrella and rain boots in preparation for an unusually wet winter.
Weather experts say there’s a 50/50 chance the skies could become nasty this holiday season. That’s due to the return of El Niño, a periodic warming of the tropical Pacific Ocean that can influence severe weather in the Bay Area, including storms that invite flooding and landslides.
The event is not new — it occurs on average every two to five years and typically lasts about 12 months — but it never fails to raise eyebrows. Depending on the strength of an El Niño event, there’s the potential for record-breaking rainfall during the fall and winter months,
Steve Anderson, a forecaster for the National Weather Service said.
The most recent El Niño occurred in 2006, but was considered weak by scientific standards. In late 1997 and early 1998, however, a powerful version helped trounce downtown San Francisco with 47 inches of seasonal rainfall, which was more than double the average, according to data compiled by Golden Gate Weather Services.
At this point, signs indicate that El Niño will be weak to moderate this time around, Anderson said. However, the National Oceanic and Atmospheric Administration warned Thursday that “further strengthening is possible.”
In the next few months, experts will continue monitoring forecasts and ocean conditions for El Niño-related patterns. The NOAA frequently tests sea surface temperatures along a narrow band in the eastern equatorial Pacific in order to monitor potential climate patterns.
“We don’t know how big it’s going to get,” said Dr. Oswaldo Garcia, chair and professor of the Geosciences Department at San Francisco
State University.
El Niño could strengthen in the coming months, but there’s a chance the trend could remain weak or reverse into La Niña-type conditions, when the waters of the eastern Pacific are cooler than normal, Garcia said.
“Nobody should be freaking out,” he said. “But everybody should be paying attention.”
In the past few years, the Pacific had been in what’s called a neutral state, but NOAA said the sea surface temperature climbed by 1.8 degrees in June.
Past El Niños have been associated with damaging storms in California — particularly in the southern part of the state — but can also help combat drought conditions, according to NOAA.
maldax@sfexaminer.com
