El Nino’s Emergence Reduces Hurricane Forecast
The Atlantic hurricane season has gotten off to such a slow start that scientists at Colorado State University, the nation's premier hurricane forecasting team, revised their forecast Tuesday, bringing the number of predicted hurricanes down to four.
The team now expects that 10 named tropical storms will form in the Atlantic basin (which also includes the Caribbean Sea and the Gulf of Mexico), with four predicted to become hurricanes and two expected to develop into major hurricanes, with sustained winds of 111 mph or greater.
"The main reason why we reduced our forecast is that El Nino has come on pretty quickly," says Phil Klotzbach, the lead author of the forecasts. El Nino is a warming of tropical Pacific Ocean water that can affect weather patterns around the globe.
"El Nino events tend to be associated with increased levels of vertical wind shear and decreased levels of Atlantic hurricane activity," says Colorado State's William Gray, who is in his 26th year of forecasting hurricanes. Wind shear weakens or destroys tropical storms before they can form into hurricanes.
The previous forecast, issued in June, predicted that 11 named storms, five hurricanes and two major hurricanes would form. A typical season sees 10 named storms, of which six are hurricanes.
So far this year, no tropical storms or hurricanes have developed in the Atlantic. Only an unnamed tropical depression formed in late May, which stayed off the Eastern Seaboard, according to the National Hurricane Center in Miami.
This calm season so far isn't unusual. Although the "official" start to the Atlantic hurricane season was June 1, the average date of the first hurricane is Aug. 14, reports Dennis Feltgen of the hurricane center. He says that since the naming of storms began in 1953, the latest the first hurricane formed was Anita on Aug. 29, 1977.
So far this year, six named storms have formed in the Pacific, including Hurricane Felicia, which reached hurricane status late Tuesday. Eastern Pacific hurricanes seldom affect the USA.
Colorado State forecasters say the chance of a major Atlantic hurricane making landfall this year along the U.S. coastline is 46%, compared with the 20th-century average of 52%.
"We will certainly see some activity this year," says Klotzbach, noting that tropical Atlantic Ocean sea-surface temperatures have warmed since June.
The National Oceanic and Atmospheric Administration will revise its forecast Thursday.