Blame it on El Niño. Thats what people did during the extreme weather of 1997-98 that brought flooding to California, tornadoes to Florida, and generally wreaked havoc to parts in between. But before anyone could breathe a sigh of relief, as soon as El Niño ended along came his cooler sisterLa Niña. And apparently shes here to stay.
Normally both El Niño and La Niña last six months to a year, but this is not the case with the current La Niña that began in 1998, according to Jim OBrien, climate expert and director of the Center for Ocean Atmosphere Prediction Studies (COAPS) at Florida State University. "This is an unusual year in that La Niña was supposed to die last summer, [but] its come back again. So basically when the water in the Pacific turned cold in July 98, its persisted and we think its probably going to persist into the spring." He says the wildfires caused by dry conditions brought on by La Niña will continue to rage in California.
What Is La Niña?
|The term El Niño originated when Peruvian fisherman noticed periodic warm water currents around Christmas. They named it "the little boy" as a reference to the Christ child. Naming the cooling trend La Niñawhich means "the little girl"followed, but La Niña is also sometimes called El Viejo or anti-El Niño or simply "a cold event." |
El Niño and La Niña are extremes of a climate cycle known as El Niño/Southern Oscillation, or ENSO. A La Niña starts when cooler subsurface water in the tropical Pacific is brought to the surface by atmospheric currents and waves in a process that is not yet understood. La Niña events sometimes occur after El Niños and can vary in intensity. While we have known about El Niño since the 1960s, scientists have only been studying La Niña since the 1980s.
Even though a La Niña starts with a cooling of water in the Pacific Ocean, its effects are felt around the world and are generally the opposite of what takes place during an El Niño. For instance, places plagued by drought during an El Niño, such as Indonesia, would be wetter than usual during La Niña. In the U.S., both events affect the jet stream. During the warm phase the jet stream runs in an east-to-west pattern, but during La Niña it comes in over the northwest, dips down, and then heads back up toward the east.
What To Expect?
The persistence of La Niña into 2000 means that spring could bring bad news for many parts of the country still suffering from last years damage. "California will be dry and were going to have extra tornadoes in the Ohio-Tennessee Valley, and a very bad drought in the coastal counties of the Carolinas, in south Georgia, Alabama, and particularly Florida," says OBrien. "There will be a lot of forest fires again this spring."
Fires arent the only dangers that could be prompted by La Niña. Depending on how long it hangs on, our next hurricane season could rival the last one. "La Niña was of course responsible for the heavy hurricane season in the Atlantic last year," says OBrien. "We had almost a record number of hurricanes, and several hit the United States." He thinks were in for at least two or three hurricanes during the next season.
La Niña also has an impact on tornadoes. Instead of tornadoes mainly occurring in Texas and up into the Midwestthe so-called Tornado AlleyLa Niña can send them into other parts of the country, such as Georgia, Tennessee, Kentucky, Michigan and even Florida, according to OBrien. "I think responsible people in that area should be very alert for the severe storms showing up this spring," he says.
As for this winter, once it gets going, past records show northerners can start waxing their skis. OBrien predicts lots of water and snow in the higher elevations of the northwest, as well as Utah, Montana, and eastern Colorado in the spring. "The people in Chicago, Detroit and Minneapolis should be using their snowblowers," adds OBrien.
"I expect it to be pretty coldthe kind of winters their grandmothers told them about." Although the northeast is not likely to see much of La Niñas effects, OBrien predicts adequate snow in upper New England.
Any Good News?
Farmers in central Florida who are worried about their strawberry and orange crops freezing can relax. "The good news is during El Niño and La Niña years, the probability of getting one of those terrible freezes for central Florida is very small," says OBrien. The drought in the southeast brought on by La Niña should be over by the end of April, so rain in May and June should mean a good season for summer crops.
Still, OBrien cautions against the tendency to blame every disaster on El Niño or La Niña. Studies conducted by his team on mosquitoes and encephalitis outbreaks, for example, have shown that the problem is not related to the climate pattern. Nevertheless, most people will breathe a sigh of relief when this La Niña finally takes her leave. "Everybodys going to be glad when this La Niñas over," he says.
Elsewhere on the Web
Answers to La Niña frequently asked questions
List of El Niños and La Niñas since 1950
Regional international forecasts
Historic U.S. El Niño and La Niña impacts
"La Niöa, El Niöo, and Atlantic Hurricane Damages in the United States"
stn2s story on the 1998 La Niña