El Niño spawns record-shattering Pacific hurricane seasons

Tuesday, December 1, 2015, 4:09 PM - Is El Nino 2015/16 a record breaker? Just from the activity in the central and eastern Pacific Ocean, the answer to that question is a definitive "Yes." Here's what happened.

As of Monday, November 30, the Atlantic and Pacific Hurricane Seasons have officially come to an end for 2015. 

Activity in the Atlantic Ocean was relatively quiet - as predicted - with a total of 11 named storms, four of which developed to hurricane strength (Danny, Fred, Joaquin and Kate), and two of which (Danny and Joaquin) developed into major hurricanes (Category 3 or stronger).

Hurricane Joaquin was particularly noteworthy, as it was the first Category 4 hurricane to impact the Bahamas during the month of October since 1866.

Although two storms made landfall in the United States - Ana on May 10 and Bill on June 16 - each with their own impacts, both were tropical storms at the time. That makes this the 10th season in a row without a major hurricane landfall in the United States (the last was Category 3 Wilma, in October 2005).

According to NOAA's summary on December 1, there was an entirely different story going on in the Pacific Ocean.

With El Niño pumping up ocean temperatures in the central and eastern equatorial Pacific Ocean, and causing the weakest vertical wind shear conditions on record over both regions, the result was record-shattering.

For the eastern Pacific Ocean:

• 18 named storms total, with 13 hurricanes, 9 of which became major hurricanes, makes this the second most active season in the eastern Pacific.

• Those 9 major hurricanes, however, represent the highest number ever seen in the eastern Pacific since reliable record keeping began in 1971.

• Hurricane Patricia, which spun up from October 20-24 to reach Category 5 strength, became the most intense hurricane ever seen in the western hemisphere. It clocked the strongest winds (325 km per hour) and logged the lowest central pressure (879 hPa) on record, beating out Hurricane Linda (at 295 km/h and 902 hPa) from 1997.

• Hurricane Sandra, which formed on Nov 23 and persisted over the next five days, is now the latest-forming Category 4 hurricane ever recorded in the Pacific, surpassing Hurricane Kenneth from 2011 in both time and intensity.

For the central Pacific Ocean:

• At 14 named storms, 8 of which became hurricanes, and 5 of those major hurricanes, the central Pacific had its busiest season on record.

• For the first time ever, three major hurricanes - Ignacio, Kilo and Jimena - were spinning in the central Pacific, east of the International Date Line, at the same time.

NOAA's GOES West satellite captured the record-breaking trio of Kilo, Ignacio, and Jimena on August 31, 2015. Credti: NOAA Environmental Visualization Lab

According to NOAA, it was the influence of El Niño that brought about both the quiet season in the Atlantic and the record-breaking seasons in the Pacific.

"El Niño produces a see-saw effect, suppressing the Atlantic season while strengthening the eastern and central Pacific hurricane seasons," Gerry Bell, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center, said in a statement. "El Niño intensified into a strong event during the summer and significantly impacted all three hurricanes seasons during their peak months."

Tropical cyclones depend on warm ocean temperatures, humid air and low vertical wind shear (the difference in speed and direction between winds near the surface and winds aloft). Although the tropical Atlantic Ocean was certainly warmer than normal during the season, dry air restricted how much moisture potential storms had access to, and strong vertical wind shear made it difficult for storms to develop and stunted their growth by cutting off their highest cloud layers. In the Pacific, some of the warmest ocean temperatures on record, coupled with the weakest vertical wind shear ever recorded, produced conditions ideal for storm formation and growth.

Although no storms are currently spinning in the Atlantic or Pacific Oceans, the end of the official season has no bearing on whether storms will develop after this. There have been post-season storms in the past, and as long as the right conditions are present - even as El Niño may be weakening - more tropical cyclones could still develop.

Sources: NOAA | NOAA Climate.gov