March 7, 2014
El Nino Forecast A Sign Of Relief For Drought-Stricken Californians
Brett Smith for redOrbit.com - Your Universe Online
El Niño is a weather-generating phenomenon based on the surface water temperatures off the western coast of South America and NOAA’s long-range forecast has said there is about a 50-50 chance that it will form this summer or fall – potentially bringing wetter weather to the southern United States.
“There are still dominoes that have to fall here. This is not a guarantee, but certainly we’re issuing this watch so folks have a heads-up,” said Michelle L’Heureux, a climate scientist at NOAA’s Climate Prediction Center in College Park, Maryland – according to Bloomberg News.
“On the precipitation side of it, you can have a more active winter storm track coming into California, and if you get a strong mode then you get a real good storm track coming across the southern US, too,” said Joel Widenor, a meteorologist at Commodity Weather Group in Bethesda, Maryland.
An El Niño doesn’t automatically mean stormy weather, but it does arrange parts of the atmosphere to make storms most likely. The phenomenon forces the jet stream to drop south over North America, guiding storms to the California coast and across the southern US. La Niña, the cycle's cool-water equivalent, is linked with drier weather in those same locations.
If El Niño were to develop this year – it would be the first since 2009-10, when a moderate El Niño was followed the next season by La Niña. Over the past two years the eastern tropical Pacific has stayed in a neutral state some experts have called "La Nada."
The decision to issue the watch came as the waters beneath the Pacific’s surface have warmed in recent weeks. Winds accumulate warm water in the western Pacific where it dips beneath the surface – eventually moving toward the coast of South America. A phenomenon referred to as a Kelvin Wave.
“Kelvin Waves are a necessary condition for El Nino but they’re not necessarily sufficient, meaning we have still yet to see what sort of impact this will have,” L’Heureux said.
She added that ocean heating has to been linked to modifications in the atmosphere, which trigger the worldwide shifts in weather patterns. The whole process is called the El Niño Southern Oscillation, or ENSO.
Most of the effects of an El Nino are determined by its strength, and predictions of strength are more difficult to make, L’Heureux said. NOAA scientists said it may be June or July before scientists know what will happen for sure.
El Niño conditions have also been shown to restrict tropical activity in the Atlantic basin. The atmospheric effects of thunderstorms pass into the western Atlantic Ocean throughout the summer months, producing strong wind shear that gets rid of tropical storms before they have a possibility to form. In 1997, during the strongest El Niño ever recorded, only 8 named storms and 3 hurricanes formed.