Will End of El Niņo Mean a Stormier Season?
As anyone who lives near the Atlantic and Gulf coast knows too well, hurricane season has been in the breeze since June 1, and will last through November; the heart of the season is mid-August through mid-October. All the latest long-range hurricane forecasts so far have predicted higher than normal storm activity this season, which is being blamed on a waning El Niņo perhaps transitioning to a weak La Niņa condition during the peak of the season.
"This is an 'El Niņo rebound' year, in which the previous winter's El Niņo has ended," according to Stu Ostro, senior meteorologist with The Weather Channel. "Such hurricane seasons have historically been dangerous. Also, water temperatures in the tropical Atlantic have been running at record high levels, which is another factor conducive to this being an active year," said Ostro. "What can't be predicted as part of a seasonal forecast is the track of each tropical storm and hurricane, so folks in all coastal locations ought to be closely monitoring the latest developments in the tropics."
El Niņo is characterized by warmer than average ocean temperatures in the Equatorial Pacific; La Niņa is characterized by colder than average ocean temperatures there. The two conditions are a naturally occurring climate cycle that varies in timing and intensity-and both entail a significant transfer of energy via water temperature that can have major climate impacts. The change in water temperature brings a change in the jet stream-which guides weather systems worldwide.
Long-term research indicates El Niņo conditions about a third of the time, La Niņa conditions about a quarter of the time, and "neutral" (or transitions from one to the other) for the rest.
Ostro noted that the El Niņo effect is more of an inhibitor of Atlantic hurricanes than La Niņa is a driver. "Atlantic hurricane seasons tend to be active also when 'neutral' conditions-neither El Niņo nor La Niņa-are present. As an extreme example, the record 2005 season was a 'neutral' one," said Ostro. "The seasonal outlooks that have been calling for a lot of storms have been based more on those record warm ocean temperatures and the end of El Niņo, rather than on whether or not La Niņa develops."
For more information about and forecasts of the 2010 hurricane season, go to www.weather.com.
Return to Current Edition