NOAA Predicts Normal or Below Normal Eastern Pacific Hurricane Season

May 21, 2009

Hurricane Norbert.

Hurricane Norbert, October 9, 2008.

High resolution (Credit NOAA)

NOAA’s National Weather Service Climate Prediction Center today announced that projected climate conditions point to a normal or below normal hurricane season in the Eastern Pacific this year. The outlook calls for a 40 percent probability of a below normal season, a 40 percent probability of a near normal season and a 20 percent probably of an above normal season.

Allowing for forecast uncertainties, seasonal hurricane forecasters estimate a 70 percent chance of 13 to 18 named storms, which includes 6 to 10 hurricanes, of which 2 to 5 will become major hurricanes (Category 3, 4 or 5 on the Saffir-Simpson Scale).

An average eastern Pacific hurricane season produces 15 to 16 named storms, with nine becoming hurricanes and four to five becoming major hurricanes. The Eastern Pacific hurricane season runs from May 15 through Nov. 30, with peak activity from July through September.

The main climate factors influencing this year’s Eastern Pacific outlook are the atmospheric conditions that have decreased hurricane activity over the Eastern Pacific Ocean since 1995 – and the possible development of El Niño.

“We expect either neutral or El Niño conditions this season,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at the Climate Prediction Center. “During this low-activity era, neutral conditions increase the chance of a below-normal season, while El Niño increases the chance of a near normal season. If significant El Niño impacts develop, as a few models suggest, we could even see an above-normal hurricane season for the Eastern Pacific region.”

The outlook is a general guide to the overall seasonal hurricane activity. It does not predict whether, where or when any of these storms may hit land.

Eastern Pacific tropical storms most often track westward over open waters, sometimes reaching Hawaii and beyond. However, some occasionally head toward the northeast and may bring rainfall to the arid southwestern United States during the summer months. Also, during any given season, two to three tropical storms can affect western Mexico or Central America. Residents, businesses and government agencies of coastal and near-coastal regions should always prepare prior to each and every hurricane season regardless of the seasonal hurricane outlook.

NOAA understands and predicts changes in the Earth's environment, from the depths of the ocean to the surface of the sun, and conserves and manages our coastal and marine resources.