Three Category 4 Hurricanes in the Pacific Ocean: How Rare Is That?

August 30,2015

A very rare meteorological event occurred Saturday evening into early Sunday morning when three Category 4 hurricanes were ongoing simultaneously in the Pacific Ocean.
At 11 p.m. EDT Saturday, Huricane Kilo (135 mph) was located well southwest of the Hawaiian Islands followed by Hurricane Ignacio (140 mph) to the east of Hawaii and Hurricane Jimena (140 mph) in the eastern Pacific. Kilo was the last of the trio to reach Category 4 status, doing so on Saturday evening. For reference, hurricanes with maximum sustained winds of 130-156 mph are classified as Category 4, which is the second highest category on the Saffir-Simpson Hurricane Wind Scale.
However, by 5 p.m. EDT Sunday both Kilo and Ignacio had begun to weaken and were classified as Category 3 hurricanes, while Jimena maintained its Category 4 status.
This is the first recorded occurrence of three Category 4 hurricanes in the central and eastern Pacific basins at the same time. In addition, it's also the first time with three major hurricanes (Category 3 or stronger) in those basins simultaneously, according to hurricane specialist Eric Blake of the National Hurricane Center.
This satellite image shows the three Category 4 hurricanes in the Pacific Sunday morning (Kilo - left, Ignacio - center, Jimena - right).

Three Category 4 hurricanes on Sunday morning in the Pacific. Kilo (left), Ignacio (center) and Jimena (right).
(NASA)

Dr. Phil Klotzbach of Colorado State University and blogger for wunderground.com said in a tweet on Saturday that this was also the first time the central Pacific, bounded by the International Date Line and 140 degrees west longitude, has had two major hurricanes (Kilo and Ignacio) ongoing at the same time. This piles on to what has already been a record hurricane season in the central Pacific basin.
Blake said on Aug. 21 that Loke was the record fifth named storm to form in the central Pacific basin this season. The others were Ela, Halola, Iune and Kilo. In addition, three eastern Pacific storms have tracked through the basin, including Guillermo, Hilda and Ignacio.
NOAA's 2015 Central Pacific hurricane season outlook cited El Nino's tendency for reduced wind shear and more storm tracks coming from the eastern Pacific as reasons to expect an active season in the central Pacific Basin.
The Pacific tropical activity can be attributed, in part, to impressively warm ocean water.
El Nino is an anomalous, yet periodic, warming of the central and eastern equatorial Pacific Ocean. For reasons still not well understood, every 2 to 7 years, this patch of ocean warms for a period of 6 to 18 months.
The eastern Pacific basin also typically sees an increase in named storms during a moderate to strong El Nino thanks to diminished vertical wind shear.
The opposite is true in the Atlantic basin, since wind shear tends to increase in a moderate to strong El Nino, particularly in the Caribbean Sea.

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