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El Niño fueling most extreme tropical cyclone season on record in Northern Hemisphere — The Washington Post

By Jason Samenow

In modern records, the Northern Hemisphere has never had as many super intense storms as 2015. An incredible 21 category four or five tropical cyclones have formed in the Northern Hemisphere in 2015, shattering the record of 18 set in 2004.

Records for these storms date back to about 1980. Prior to that, tropical cyclone data is less reliable.

These 21 category four or five storms are comprised of both high-end hurricanes and super typhoons, which share the same characteristics, but are called different things. They are the fiercest storms that form on the planet.

The amount and degree of storminess may come as a surprise, since the tropical Atlantic Ocean has produced below normal activity this year. But tropical activity in the tropical Pacific has been super-charged, fueled by the record-challenging El Niño event, which has boosted ocean temperatures in the central and eastern tropical Pacific.

Tropical cyclones thrive off of warm ocean waters, which have soared to previously unsurpassed levels in vast expanses of the Pacific.

Every section of the sprawling Pacific Ocean basin in the Northern Hemisphere has experienced the most major storms (category 3 or higher) in at least 20 years.

Phil Klotzbach, the Colorado State University tropical weather researcher, shared the following statistics through October 20:

In the northeast Pacific

  • There have been nine category three or higher hurricanes, the most since 1992 (which had 10 of this date; 1993 and 2014 also had nine).
  • There have been 23 total named storms, the most since 1992 (which had 26 as of this date).

In the central Pacific

  • There have been five category three or higher hurricanes, the most on record. The old record was three (from 1994).
  • A record 14 named storms have at some point resided within the basin including six that originated from the Northeast Pacific. The previous record for total number of storms was 10 (from 1982).
  • A record eight named storms have formed within the basin. The previous record was four (1982).

In the northwest Pacific

  • There have been 14 category three or higher typhoons, the most since 1965.
  • 17 typhoons have formed, the most since 2004, which had 18.
  • Eight super typhoons (category 4 and 5) have formed, the most since 1997 which had nine.

Not only is the number of the most intense storms at record levels in the Northern Hemisphere, but also the metric that describes the amount of storm energy overall, known as Accumulated Cyclone Energy or ACE. “We’re in a dead heat with 2004 in terms of ACE,” Klotzbach said.

The surge in activity in the central Pacific Ocean, in particular, has impressed Klotzbach. “It has broken nearly every possible record,” he said. “Sea surface temperatures off Hawaii have been extraordinarily warm, much warmer than anything in the past.”

Wind shear, which is often destructive to developing tropical cyclones, has been “crazy low”, Klotzbach added.
Hurricane Olaf, the latest category four storm to form in the central Pacific, is among the many to benefit from the unusually favorable environmental conditions for intensification.
Olaf has distinguished itself in several ways in central Pacific cyclone history:

  • It is the strongest hurricane so late in the year (Eric Blake via Twitter )
  • Is is the latest storm on record to cross into central Pacific from northeast Pacific (Phil Klotzbach via Twitter)
  • It is the closest category 4 hurricane to the equator (i.e. farthest south) in the Western Hemisphere on record (Eric Blake via Twitter)

While El Niño, in particular, has spurred the hyper activity in the Pacific, a blob of warm water in the central Pacific, somewhat independent from El Niño has also contributed. Klotzbach attributed the warm water there to the Pacific meridional mode, a cyclical pattern.

Global warming may also be playing some role in the intensity attained by these storms. Ocean temperatures in the Northern Hemisphere have ranked warmest on record year-to-date, 1.4 degrees above the long-term average.

Klotzbach hesitated to make a direct link between the climate warming and cyclone activity noting it’s unclear how the warming impacts El Niño, the primary driver of the activity. He added that the amount of available historical cyclone data is short for establishing solid connections with recent warming trends.

NOAA’s Geophysical Fluid Dynamics Laboratory (GFDL) has concluded the activity we’re observing this year may be a harbinger of the future. “There are better than even odds that the numbers of very intense (category 4 and 5) hurricanes will increase by a substantial fraction in some basins [in the coming century],” it wrote in a synthesis of projected impacts of warming on hurricane activity, updated Sept. 30.

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