Perhaps because weather prediction is one of those thankless endeavors in which only big mistakes are noticed, the National Oceanic & Atmospheric Administration was cautious in its announcement last week that another El Niño is on the horizon.
NOAA said that slightly warmer ocean temperatures point to a return of El Niño, the capricious climatic system that caused a spate of weather woes in 1997 and 1998.
But the agency noted, "conditions have not developed to the point that guarantees sustained growth of the event." It offered no timeline for when El Niño might develop, and did not say whether people in landlocked areas should purchase some quality boating equipment.
But if El Niño conditions do occur during the next few years, researchers say they will probably be much milder than those of the last system, which killed 24,000 people worldwide, displaced 6 million and caused $34 billion in damage, according to NOAA. Moreover, prediction technology has improved to the point that regional and even local weather can now be finely gauged, allowing regions to better prepare for El Niño's effects.
In its El Niño report, NOAA said that its temperature sensors had detected a 2 to 4 degree (Celsius) temperature increase in a band of the Pacific Ocean that stretches from Papua New Guinea to South America.
NOAA maintains 70 permanently moored buoys in that region that continuously record ocean conditions and transmit them, in real time via satellite, to researchers. (Here are the latest wind and temperature conditions, and here's a Flash-based online presentation that explains how the system works.)
Vernon Kousky, the lead forecaster at NOAA's prediction center, said "for the ocean, that (temperature increase) is rather substantial." It might be enough, he suggested, to affect cloud and rain patterns in the tropical Pacific basin, which causes El Niño.
But Kousky said that during the last El Niño, temperatures rose by as much as 10 degrees, "which means that so far this one looks relatively weak."
El Niño events can occur every four to five years, but a strong one is often followed by a mild one. The El Niño in 1997 was one of the strongest in the last 125 years.
Like most climate researchers, NOAA scientists rely on supercomputer modeling to predict weather changes, and Kousky said his team isn't using any substantially better technology than it had available in 1997.
The major holes in the agency's predictions, he said, are theoretical rather than technological. "We use the supercomputers to simulate the circulation in both the atmosphere and ocean, and it's best if we could couple those models, to see how one affects the other," Kousky said. "They're currently working in a semi-coupled state -- we don't yet have the knowledge base to really couple them, because we don't yet fully understand the physics of it."
Kousky said technological improvements are slowly helping researchers to understand the delicate dance between ocean and atmosphere, but "it will take a number of years until we're fully sophisticated."
That's on a global scale, however. At the same time that researchers have been improving their abilities to predict long-range phenomena like El Niño and its cousin La Niña, they've also become more adept at predicting local weather "at finer resolutions," according to Peter Ungaro, who is IBM's vice president for high-performance computing.
Ungaro said IBM's Deep Thunder project is focused on making short-term, local predictions very accurate.
The system combines very closely spaced weather sensors -- as close as 1 kilometer apart -- and a lot of supercomputing power to predict what the weather will be like over a short term in a small region (a New York City-size area, for instance.)
Because the computing power is great -- "in the range of 2,000 to 3,000 of times the CPU-power you have on your desktop" -- Deep Thunder allows researchers to do "ensemble runs, which is doing the same forecasts many times and changing the input parameters by a small amount each time," Ungaro said.
This lets meteorologists pinpoint the specific regions most likely to be affected by severe weather.
"If an area is going to flood or a hurricane is coming in, an early warning system would evacuate the right people earlier," Ungaro said.
The system could also stem the economic damage associated with erratic weather. "For people who grow oranges in the Southeast," he said, "when it starts to get near freezing temperatures, they can heat up their oranges through the night and not lose their crops."
In the future, such systems can be even further refined to produce something like a "personal weather forecast," Ungaro said. IBM showed off such a system at the 1996 Olympic Games in Atlanta, in which the system accurately predicted that it was going to rain during the closing ceremonies, but that the stadium wouldn't be affected.
