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Naysayers:
Some experts dispute dire El Nino predictions
From San Francisco Bureau Chief Greg Lefevre
(CNN) -- Has the El Nino hype gone too far? A vocal group of meteorologists in California thinks so. They have grown increasingly skeptical about projections of massive rainfall on the U.S. West Coast this winter.
"Some of the numbers of five times normal rainfall for example. They're just not possible from a meteorological point of view," said Jan Null, the lead forecaster of the National Weather Service's Monterey, California, office.
Null has lectured local emergency officials on preparedness. He expects more rain than usual, but less than the 500 percent jump forecast by some meteorologists over the summer. He predicts the increase will be closer to 50 percent.
Null said that while it's always nice to be ready, warnings about this El Nino -- which some say could be the worst in a century -- have been overstated.
Clive Dorman of the Scripps Institution of Oceanography agrees that rainfall in California this winter will fall short of predictions.
"The heaviest rainfall we ever got was about two-point-eight times normal. That was once out of 135 years," he said. And, he adds, that wasn't during a documented El Nino year.
Null also differs with those who attribute the unusually warm off the California coast to El Nino.
"Warm waters off our coast were incorrectly linked to El Nino. It was offshore winds," Null told CNN.
Winds flowing west off the deserts, heated as they flowed downhill to the sea, bathed the beaches in hot air and raised the water temperatures by 2 to 5 degrees, according to Null.
Null charted the El Nino years since 1947. Of the eight heaviest El Nino years, he says, rainfall averaged only 35 percent above normal.
Only two years were significantly above normal: 1957, which saw a 70 percent increase, and 1982, which saw an 80 percent increase. Two of the heavy El Nino years, 1965 and 1991, were drought years with less than normal rainfall.
As evidence that early forecasts of this El Nino were way off mark, scientists point to what they call "the incredible shrinking predictions."
Last July some were predicting 500 percent of normal rainfall, then those forecasts were revised down to 200 percent.
By September, experts were warning of rainfalls 180 percent above normal. And early October, Wayne Higgins of the Climate Prediction Center cut it further: "We're talking more about something in the range of 150 percent of normal."
Other scientists hedge even further.
"If it's spread out over a bunch of months it's going be indistinguishable for most people," Dorman said.
Perhaps most important, Null says, is comparing the 1982 El Nino conditions and the winter that followed with the present El Nino measurements. Null says none of the current measurements are as great as in 1982.
For the record, the Bay Area's heaviest rainfall came more a century ago. In 1862 it rained 49 inches. Since then it's never come close.
It's tough to accurately predict effects of El Nino because science has data on relatively few El Nino's to study and each El Nino has been wildly different from the other.
Is it a mistake to plan for disaster? Not at all, says Dan Lunsford, head of San Leandro, California, Emergency Services Department. "We instruct and train our community to prepare each winter for the worst-case scenarios."
Norm Hoffmann, Meteorologist in Charge, National Weather Service, doesn't worry that El Nino may fizzle. "Odds are that it looks like it's going to be above normal 'precip.' Be prepared," he says.
Related sites:
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- National Weather Service San Francisco
- NWS El Nino Page
- Scripps El Nino Page
- Experimental Climate Prediction Center at Scripps
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