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Hurricane forecasts were off, but nobody is complaining about our good luck.
By JACOB H. FRIES, Times Staff Writer
Published November 29, 2007
No one is complaining. Not even those Boy Scout types who loaded up on extra batteries, granola bars and canned peas for the killer storm that never came.
But now, with the official end of the 2007 hurricane season on Friday, people are scratching their heads. What happened? Where were all the storms? Is hurricane prediction just a load of bunk?
Hold on. Before we toss out the prognosticators, let's ask an expert.
What did we learn this year?
"We learned that seasonal forecasts are wrong a lot," said Jeff Masters, a former National Oceanic and Atmospheric Administration meteorologist and co-founder of wunderground.com, a weather forecasting Web site. "They do have some skill, but it's not a lot. And we're finding out that sometime, you have multiple years in a row that seasonal forecasts go bad. ... This was a blown one."
Not exactly confidence inspiring.
"Too much attention is given to these seasonal forecasts by the public," Masters said. "They are not very good yet."
The preseason forecast: The National Hurricane Center predicted an above average season, with 13-17 named storms for the Atlantic, seven to nine of those developing into hurricanes and three to five of those expected to become major hurricanes (111 mph or more).
Reality: There were 14 named storms, five of them hurricanes, two of them major ones (Dean and Felix) during hurricane season, which runs from June 1 to Nov. 30. Only one, Humberto, a Category 1 storm, hit the United States, rolling across Texas and Louisiana in September.
Forecasters say several things played havoc on their calculations. For one, there was an unexpected amount of upper level winds, also called shear, that inhibited the formation of storms in September, the peak of the season. Also, African dust spread across the Atlantic earlier in the year and absorbed warmth in the atmosphere.
Take those factors, add in the chaotic nature of the atmosphere, the rise of global warming and the holes in our understanding and - voila! - mistakes will happen.
In 2006, experts expected 17 named storms. We got nine. In 2005, they predicted 13. We got 27.
"Frankly, it's not a simple problem," said Dr. Bob Weisberg, a distinguished professor and oceanographer at the University of South Florida St. Petersburg. "I'm not denigrating those people doing the forecasting, but it's a much more complex problem than some of the prognosticators have been indicating."
The seasonal forecasts were never intended to guide the average person's hurricane preparation. They estimate the activity of the hurricane season, not specifically where storms will hit or how devastating they will be. Insurance companies and some emergency managers look at the predictions, but for most people, they hold little meaning.
"We always try to tell the public, 'Don't do anything different based on the seasonal forecast. You need to prepare your family and your business every season,'" said Chris Landsea, science and operations officer for the National Hurricane Center in Miami. "Because if it hits your city, it's a busy year for you."
Landsea said that while forecasters have missed the mark when predicting a season's activity, they have become much more proficient at anticipating a storm's likely path - information important to public safety.
"I would hope the general public would not see the busted seasonal forecast and assume we have the same difficulties on the track forecasting," Landsea said. "Our tracks have half the errors now than they did 15 years ago."
Every year, our understanding of hurricanes improves, as do the models used to predict their behavior.
Earlier this year, the British government released a new approach, a "numerical model," that takes the analysis out of the hands of mere mortals and gives it to computers. It also gives less weight to historical data, which some scientists say is flawed because of global warming. Scientists and forecasters say the approach, as well as other models being developed, hold great promise for the future.
Okay, but what about next year? Look into the crystal ball: Good, bad, apocalyptic?
"Ever since 1995, we've been in this active period," Masters said. "So it's always good to bet on a more active hurricane season than normal."
[Last modified November 28, 2007, 22:42:48]