Category 5 hurricanes are tropical cyclones that reach Category 5 intensity on the Saffir-Simpson Hurricane Scale. They are the most catastrophic hurricanes that can form on planet Earth. They are rare in the eastern Pacific Ocean and generally form only once every several years. In general, Category 5s form in clusters in single years. Landfalls by such storms are rare due to the generally westerly path of tropical cyclones in the northern hemisphere.
The term "hurricane" is used for tropical cyclones in the Pacific Ocean, north of the equator and east of the international date line. A Category 5 Pacific hurricane is therefore a tropical cyclone in the north Pacific Ocean that reached Category 5 intensity east of the international dateline. Identical phenomena in the north Pacific Ocean west of the dateline are called "typhoons" or "super typhoons". Category 5 super typhoons generally happen several times per season, so cyclones of that intensity are not exceptional for that region. This difference in terminology therefore excludes storms such as Super Typhoon Paka and Super Typhoon Oliwa of 1997, which formed east of the dateline but did not reach Category 5 intensity until after crossing the dateline.
Contents |
| Saffir–Simpson Hurricane Scale | ||||||
| TD | TS | C1 | C2 | C3 | C4 | C5 |
A Category 5 hurricane sustained winds of greater than 135 knots (155.4 mph; 250.0 km/h).[1] Sustained winds refers to a one-minute average measured 10 metres (32 ft 9.7 in) above the ground. Short gusts can be up to 50% higher than the sustained winds.[2] As a tropical cyclone is moving, its wind field is asymmetric. In the northern hemisphere, the strongest winds are on the right side of the storm (relative to the direction of motion). The highest winds given in advisories are those from the right side.[3]
Between the 1959 and 2010 seasons inclusive, only 14 hurricanes have reached and were recorded as a Category 5. There are no known Category 5 storms occurring before 1959. It is possible that some earlier storms reached Category 5 over open waters, but they were never recognized because they never affected land and remained at sea.[4]
This lists all of the Category 5 hurricanes in the order in which they formed. Only 1994's Hurricane Emilia and 2006's Hurricane Ioke have reached Category 5 intensity more than once; that is, by weakening into a Category 4 or weaker storm and then re-strengthening to a cat 5 again.
Before the advent of reliable geostationary satellite coverage in 1966, the number of eastern Pacific tropical cyclones was significantly underestimated.[5] It is therefore very possible that there are additional Category 5's other than those listed, but they were not reported and therefore not recognized. However, the lack of Pacific Category 5's during the late 1970s, 1980s, and early 1990s, is certain.[4]
| Name | Season | Max. 1 min. average sustained wind | |||
|---|---|---|---|---|---|
| knots | km/h | mph | |||
| 1950s | |||||
| Patsy | 1959 | 150 | 280 | 175 | |
| "Mexico" | 1959 | 140 | 260 | 160 | |
| 1970s | |||||
| Ava | 1973 | 140 | 260 | 160 | |
| 1990s | |||||
| Emilia | 1994 | 140 | 260 | 160 | |
| Gilma | 1994 | 140 | 260 | 160 | |
| John | 1994 | 150 | 280 | 175 | |
| Guillermo | 1997 | 140 | 260 | 160 | |
| Linda | 1997 | 160 | 300 | 185 | |
| 2000s | |||||
| Elida | 2002 | 140 | 260 | 160 | |
| Hernan | 2002 | 140 | 260 | 160 | |
| Kenna | 2002 | 145 | 270 | 165 | |
| Ioke | 2006 | 140 | 260 | 160 | |
| Rick | 2009 | 155 | 285 | 180 | |
| 2010s | |||||
| Celia | 2010 | 140 | 260 | 160 | |
Hurricanes have reached Category 5 intensity during every month from June to October. The earliest Category 5 has formed in a season is June 7, by 1973's Hurricane Ava. The latest Category 5 to form in a season is the 1959 Mexico hurricane, which reached peak intensity on October 27. Hurricanes Ava, Gilma, Guillermo, Linda, and Rick are the most intense storms to form in their respective months. There have been no May, November, or off-season Category 5's.[4]
Two Pacific hurricanes are known to have reached Category 5 intensity multiple times: Emilia and Ioke. Both did it twice, and Ioke reached Category 5 status a third time as a typhoon while in the Western Pacific.[4] Hurricane Ioke was tied for the longest-lasting Category 5 hurricane recorded, spending 42 hours at that strength,[6] while hurricanes John and Linda had the longest time spent consecutively at that intensity.[4]
| Name | Date attained | Date lost | Time as a Category 5 |
|---|---|---|---|
| Ava | June 7 | June 8 | 12 hours |
| Celia | June 24 | June 25 | 12 hours |
| Emilia | July 19 | July 20 | 18 hours |
| July 20 | July 21 | ||
| Gilma | July 24 | July 25 | 18 hours |
| Elida | July 25 | July 25 | 6 hours |
| Guillermo | August 4 | August 5 | 12 hours |
| John | August 22 | August 24 | 42 hours |
| Ioke | August 24 | August 25 | 42 hours |
| August 26 | August 26* | ||
| Hernan | September 1 | September 1 | 12 hours |
| Patsy | September 6 | September 6 | 6 hours |
| Linda | September 12 | September 13 | 42 hours |
| Rick | October 17 | October 18 | 24 hours |
| Kenna | October 24 | October 25 | 18 hours |
| "Mexico" | October 27 | October 27 | 6 hours |
| *Ioke did not lose Category 5 status on August 26, however, it moved into the Western North Pacific, and thus was no longer considered a hurricane, but rather a typhoon. | |||
For its first time as a Category 5, Emilia was at that intensity for 6 hours; the second time was for 12 for a total of 18 hours.[7] For its first time as a Category 5, Ioke was at that intensity for 18 hours; the second time was 24 additional hours east of the dateline, giving a total of 42 hours.[4]
| Name | Lowest Pressure | |
|---|---|---|
| Millibars | Inches of Mercury | |
| Linda | 902 | 26.6 |
| Rick | 906 | 26.7 |
| Kenna | 913 | 27.0 |
| Ava | ≤915 | ≤27.0 |
| Guillermo | 919 | 27.1 |
| Gilma | ≤920 | ≤27.2 |
| Ioke | 920 | 27.2 |
| Elida | 921 | 27.2 |
| Hernan | 921 | 27.2 |
| Emilia | 926 | 27.3 |
| Celia | 926 | 27.3 |
| John | ≤929 | ≤27.4 |
| "Mexico" | ≤958 | ≤28.3 |
| Patsy | unknown | unknown |
The minimum central pressure of these storms is, for the most part, estimated from satellite imagery using the Dvorak technique. In the case of Kenna[8] and Ava,[9] the central pressure was measured by hurricane hunter aircraft flying into the storm. In the case of the 1959 Mexico hurricane, the best central pressure reading was measured after landfall.[4] Because of the estimation of central pressures, it is possible that other storms more intense than these have formed.[10]
The reason for estimating the pressure is the fact that most of these storms did not threaten land.[11] As Kenna was threatening land, its pressure was measured by a dropsonde.[8] Hurricane Ava never threatened land.[4] However, it was flown into to test equipment and conduct research.[9]
Before 1997, the means for estimate pressure from satellite imagery was not available. Older storms have incomplete pressure readings taken by ships, land-based observations, or recon aircraft. Ava's minimum known pressure was measured when it was a Category 4, for example.[4] John and Gilma have incomplete pressures because the Central Pacific Hurricane Center, in general, did not publish pressure on systems in the central Pacific (140°W to the dateline) at the time.[12]However, it should be noted that this list is not identical to the list of most intense Pacific hurricanes. The most intense known Category 4 storms in the eastern Pacific were 1994's Hurricane Olivia and 2001's Hurricane Juliette. The lowest pressure of these two storms were 923 millibars, which exceedes that of some category 5's, such as Emilia.[4]
In the eastern Pacific, Category 5 hurricanes usually occur only in El Niño years. During El Niño years, conditions are more favorable for tropical cyclones because of warmer sea surface temperatures and reduced wind shear. This is why Category 5's cluster in single seasons. The effects of El Niño are most significant in the central Pacific (140°W to the dateline).[13]
The general lack of Category 5's in non warm-ENSO years is because of there being limited space for development. The prevailing ocean currents of the area carry warm water to the west. As there is no large piece of land to block the water and cause it to "pile up" like in the Atlantic, the area suitable for all tropical cyclones is small. Farther out to sea, while waters are still warm, wind shear limits the development of tropical cyclones in the waters south of Hawaii. This makes an otherwise ideal region unfavorable for tropical cyclones.
This does not mean that a Category 5 cannot form outside of an El Niño event. The entire year of 1959 was neither an El Niño or a La Niña, but had two Category 5's (Patsy and the Mexico Hurricane) and was the deadliest Pacific hurricane season ever recorded in history. Most of 1973 was during a La Niña, which reduces tropical cyclone activity in the eastern Pacific, yet Hurricane Ava, a category 5 hurricane, formed in June of that year.[14] The 2009 season and the 2010 season are the only two seasons in which a Category 5 hurricane formed in consecutive years (Rick and Celia, respectively).[15]
Of all of the Category 5 Pacific hurricanes, the only ones to make landfall at any intensity were the 1959 Mexico hurricane, Hurricane Kenna, and Hurricane Rick. The 1959 hurricane was the only one to make landfall as a Category 5, Kenna had weakened to a Category 4 at the time of its landfall, and Rick was a tropical storm at its landfall. The Mexico Hurricane and Kenna are the strongest and third strongest landfalls by east Pacific tropical cyclones, respectively—the second strongest was 1976's Hurricane Madeline, which didn't reach Category 5 strength, but made landfall as a stronger Category 4 storm than Kenna.[8]
In addition to these three systems, Hurricanes John, Linda, and Ioke all threatened land for a while. John and Ioke had minimal impact on Johnston Atoll and John caused heavy surf in Hawaii.[7] Linda was briefly forecast to approach southern California, and it passed close to Socorro Island near peak intensity.[6][16]
The reason for the lack of landfalls is that tropical cyclones in the northern hemisphere usually travel to the west.[17] In the Atlantic, this sends hurricanes towards North America. In the eastern Pacific, this sends tropical cyclones out into the open ocean to dissipate over waters too cool to support them or in environments with high wind shear. Hawaii, the only heavily populated island chain in the eastern Pacific, is protected from most hurricanes by a subtropical ridge and is small enough to avoid being hit simply due to low odds.
| Book: Category 5 Pacific hurricanes | |
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