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End of 2015 hurricane season

Below-normal Atlantic hurricane season, but active eastern and central Pacific season shatters records.

Image credit: NASA Earth Observatory/Joshua Stevens

The maps above and below are based on data from Unisys Weather, which compiles information from the U.S. National Weather Service and the Joint Typhoon Warning Center. The maps show the tracks and intensity of all tropical cyclones in 2015Image credit: NASA Earth Observatory/Joshua Stevens

Hurricane season in the Atlantic Ocean, and eastern and central Pacific Ocean, ended a week ago (November 30) and NOAA published a summary of the season on December 1, 2015. NOAA wrote that the Atlantic season stayed below normal. Meanwhile, hurricanes in the eastern and central Pacific – where this year’s above-average El Niño is ongoing – were above normal with both regions shattering all-time records. Hurricanes and cyclones in 2015 menaced regions that do not usually see them: the central Pacific Ocean and the Arabian Sea (northwest Indian Ocean). NOAA said its scientists credit El Niño as the leading climate factor influencing both the Atlantic and Pacific hurricane seasons this year.

The Atlantic was quieter than usual, the third year in a row with below-average storm activity, with 11 named storms, including four hurricanes (Danny, Fred, Joaquin and Kate). One storm, Fred, became the easternmost hurricane on record in the Atlantic, lashing the Cabo Verde islands in September. In November, Hurricane Kate hit The Bahamas, becoming one of the latest storms ever recorded in the islands.

Although no hurricanes made landfall in the United States this year, two tropical storms – Ana and Bill – struck the northeastern coast of South Carolina and Texas, respectively. Hurricane Joaquin is the first Category 4 hurricane since 1866 to hit the Bahamas during the month of October.

Image credit: NASA

Image credit: NASA

The waters of the eastern Pacific warmed significantly in 2015 with the arrival of a potent El Niño. According to NOAA data, 18 named storms and 13 hurricanes hit the region, nine of them major — the most since reliable records were started in 1971. Fueled by warm air and sea temperatures, Patricia grew rapidly into the strongest hurricane ever recorded in the Western Hemisphere.

In the North Central Pacific – the region above the equator from 140 to 180 degrees western latitude — 14 named storms and eight hurricanes formed or moved into the region. The previous record for the region was four hurricanes in 1982. Five of this year’s storms reached category 3 or above, eclipsing the previous record of three. At one point in August, three major hurricanes spun through the region east of the International Date Line at the same time, the first time any meteorologist has seen such activity.

Image credit: NASA

Image credit: NASA

In the western Pacific, near Asia and the islands of Oceania, the season was noteworthy not for the total number of storms, but for the number of intense ones. Fifteen typhoons grew to category 3 strength or higher in 2015, said NOAA, tying records set in 1958 and 1965. Near the end of the tropical storm season, two cyclones stirred up the waters of the Arabian Sea. The region is normally so dry and windy that storms cannot reach shore. Yet both a hurricane and a tropical storm made landfall in Yemen and nearby Socotra Island within a week in November.

Gerry Bell, Ph.D. islead seasonal hurricane forecaster at NOAA’s Climate Prediction Center. Bell said:

El Niño produces a see-saw effect, suppressing the Atlantic season while strengthening the eastern and central Pacific hurricane seasons. El Niño intensified into a strong event during the summer and significantly impacted all three hurricanes seasons during their peak months.

Bell said that El Niño suppressed the Atlantic season by producing strong vertical wind shear combined with increased atmospheric stability, stronger sinking motion and drier air across the tropical Atlantic, all of which make it difficult for tropical storms and hurricanes to form and strengthen. However, El Niño fueled the eastern and central Pacific seasons this year with the weakest vertical wind shear on record.

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Bottom line: Hurricane season in the Atlantic Ocean, and eastern and central Pacific Ocean, ended on November 30, 2015. According to NOAA, the Atlantic season stayed below normal. Meanwhile, hurricanes in the eastern and central Pacific – where this year’s above-average El Niño is ongoing – were above normal with both regions shattering all-time records. Hurricanes and cyclones in 2015 menaced regions that do not usually see them

Via NOAA

Deborah Byrd

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