Kona storm

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A subtropical storm on December 19, 2010, originally a Kona storm 98C dec 19 2010 0000Z.jpg
A subtropical storm on December 19, 2010, originally a Kona storm

Kona storms (also called Kona lows) are a type of seasonal cyclone in the Hawaiian Islands, usually formed in the winter from winds coming from the westerly "kona" (normally leeward) direction. [1] They are mainly cold core cyclones, which places them in the extratropical cyclone rather than the subtropical cyclone category. Hawaii typically experiences two to three annually, which can affect the state for a week or more. Among their hazards are heavy rain, hailstorms, flash floods and their associated landslides, high elevation snow, high winds which result in large surf and swells, and waterspouts.

Contents

Origin of term

Kona is a Hawaiian language term (related to similar words in other Polynesian languages) for the western (to southwestern) side of an island. [2] The Kona District for example on the Big Island of Hawaiʻi still uses this name. Although normally dry and leeward, the traditional easterly (to northeasterly) tradewinds slacken and reverse during one of these cyclones.

Character of the cyclones

Once termed as subtropical cyclones, a change in the definition of the term during the early 1970s makes categorization of the systems not straightforward. Kona lows are typically cold core, making them extratropical cyclones. [3] However, they generally share the subtropical cyclone characteristic of losing their associated weather fronts with time, since the cyclones tend to retrograde slowly.

Otkin and Martin identified three types of kona storms: cold-frontal cyclogenesis cyclones (CFCs), trade wind easterlies, and cold-frontal cyclogenesis/trade wind easterlies cyclones. Of the three, CFC cyclones are the most common. [4]

Rainfall in a Kona storm is more pronounced than a cold front storm, and most intense from south to east of the storm and in front of the storm's center. Steady rains may last from several hours to days, with longer lasting storms typically interrupted by intervals of lighter rain and partial clearing. Intense showers may appear on more moderate but steady rain. [1]

Frequency and effects

Some winters occur without a single Kona storm, with a high of four or five. Hawaii typically experiences two to three annually [5] between October and April. [6] The cyclone events for Hawaii can be long-lived, affecting the state for a week or more. [7] Kona lows produce a wide range of weather hazards for Hawaii. Among them are heavy rain, hailstorms, flash floods and their associated landslides, high winds which result in large surf and swells, waterspouts, and heavy snows on the higher mountains. [8]

Kona winds

Kona winds are associated with cyclones with central pressures below 1,000.0 hectopascals (29.53 inHg) which pass within 500 miles/820 km northwest of the Hawaiian Islands. Strong Kona winds usually last for a day. Considerable damage is caused to boats lying southwest of the islands. On land, trees are uprooted and roofs can be blown off homes. When passing through mountain gaps and over mountains, downsloped winds gust over 100 mph/165 km/h, which causes much of the destruction. [9]

Examples

A kona storm on November 4, 1995 KonaLowNovember041995IR.jpg
A kona storm on November 4, 1995

The most powerful Kona storm in the last fifty years struck the Hawaiian islands between 8 January and 11 January 1980. The low pressure primarily responsible for the severe conditions had a barometric pressure of 975mb on January 8, while passing north of the state, one of the lowest pressure readings ever recorded in Hawaiian waters as a result of an extratropical storm. [10] The storm caused severe weather across the entire state, forcing the closure of all airports. Rainfall from the storm was extremely heavy, surpassing twenty inches in many locations, particularly on the Big Island and Maui. High surf from the storm caused extensive damage, particularly along the Kona coast of the Big Island, where the towns of Kailua-Kona and Puako received extensive damage. [10] Winds from the storm averaged around 40-50 mph on the open ocean, but varied tremendously on land due to unique geographic features. Some areas experienced wind gusts well over hurricane force, including a low altitude gust of 106 mph (171 km/h) on Lahaina Roads, Maui. Haiku, on the windward coast of Maui, experienced a wind gust of 75 mph (121 km/h). On the high mountain summits of the Big Island and Maui, winds of over 110 mph (180 km/h) were recorded. Damage from the storm was estimated at between $25 and 35 million (in 1980 dollars). [10] [11]

In December 2008, lightning strikes from a Kona storm caused the entire power grid of the island of Oahu to black out, while then President-elect, Barack Obama was visiting. [12] In December 2010, a Kona storm became fully subtropical and eventually became Tropical Storm Omeka.

The fourth episode of the sixth season of Magnum, P.I. is entitled "The Kona Winds."

Related Research Articles

<span class="mw-page-title-main">Cyclone</span> Large scale air mass that rotates around a strong center of low pressure

In meteorology, a cyclone is a large air mass that rotates around a strong center of low atmospheric pressure, counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere as viewed from above. Cyclones are characterized by inward-spiraling winds that rotate about a zone of low pressure. The largest low-pressure systems are polar vortices and extratropical cyclones of the largest scale. Warm-core cyclones such as tropical cyclones and subtropical cyclones also lie within the synoptic scale. Mesocyclones, tornadoes, and dust devils lie within smaller mesoscale. Upper level cyclones can exist without the presence of a surface low, and can pinch off from the base of the tropical upper tropospheric trough during the summer months in the Northern Hemisphere. Cyclones have also been seen on extraterrestrial planets, such as Mars, Jupiter, and Neptune. Cyclogenesis is the process of cyclone formation and intensification. Extratropical cyclones begin as waves in large regions of enhanced mid-latitude temperature contrasts called baroclinic zones. These zones contract and form weather fronts as the cyclonic circulation closes and intensifies. Later in their life cycle, extratropical cyclones occlude as cold air masses undercut the warmer air and become cold core systems. A cyclone's track is guided over the course of its 2 to 6 day life cycle by the steering flow of the subtropical jet stream.

<span class="mw-page-title-main">Subtropical cyclone</span> Cyclonic storm with both tropical and extratropical characteristics

A subtropical cyclone is a weather system that has some characteristics of both tropical and an extratropical cyclone.

<span class="mw-page-title-main">Low-pressure area</span> In meteorology, a cyclone

In meteorology, a low-pressure area, low area or low is a region where the atmospheric pressure is lower than that of surrounding locations. Low-pressure areas are commonly associated with inclement weather, while high-pressure areas are associated with lighter winds and clear skies. Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis forces. Low-pressure systems form under areas of wind divergence that occur in the upper levels of the atmosphere (aloft). The formation process of a low-pressure area is known as cyclogenesis. In meteorology, atmospheric divergence aloft occurs in two kinds of places:

<span class="mw-page-title-main">Westerlies</span> Prevailing winds from the west

The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and trend towards the poles and steer extratropical cyclones in this general manner. Tropical cyclones which cross the subtropical ridge axis into the westerlies recurve due to the increased westerly flow. The winds are predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere.

<span class="mw-page-title-main">Tropical wave</span> Type of atmospheric trough

A tropical wave, in and around the Atlantic Ocean, is a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which moves from east to west across the tropics, causing areas of cloudiness and thunderstorms. Tropical waves form in the easterly flow along the equatorial side of the subtropical ridge or belt of high air pressure which lies north and south of the Intertropical Convergence Zone (ITCZ). Tropical waves are generally carried westward by the prevailing easterly winds along the tropics and subtropics near the equator. They can lead to the formation of tropical cyclones in the north Atlantic and northeastern Pacific basins. A tropical wave study is aided by Hovmöller diagrams, a graph of meteorological data.

<span class="mw-page-title-main">Cyclogenesis</span> The development or strengthening of cyclonic circulation in the atmosphere

Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere. Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyclone, and at any size from the microscale to the synoptic scale.

<span class="mw-page-title-main">Tropical Storm Gilda (1973)</span> Atlantic tropical storm in 1973

Tropical Storm Gilda in 1973 was the first documented tropical cyclone on record to transition into a subtropical cyclone. It formed on October 16 in the western Caribbean Sea from a tropical wave, and strengthened to reach peak winds of 70 mph (110 km/h) before striking Cuba. It later moved slowly through the Bahamas before weakening to tropical depression status. On October 24, with the assistance of a cold front off the coast of the eastern United States, Gilda transformed into a subtropical storm, becoming very large and strong. The storm later accelerated northeastward and became extratropical, ultimately dissipating near Greenland.

<span class="mw-page-title-main">Hurricane Gustav (2002)</span> Category 2 Atlantic hurricane

Hurricane Gustav was a Category 2 hurricane that paralleled the East Coast of the United States in September 2002 during the 2002 Atlantic hurricane season. It was the seventh named storm and first hurricane of the season. Initially a subtropical depression north of the Bahamas, Gustav passed just to the east of the Outer Banks, North Carolina as a tropical storm before traveling northeastward, making two landfalls in Atlantic Canada as a Category 1 hurricane. The storm was responsible for one death and $100,000 in damage, mostly in North Carolina. The interaction between Gustav and a non-tropical system produced strong winds that caused an additional $240,000 (2002 USD) in damage in New England, but this damage was not directly attributed to the hurricane.

<span class="mw-page-title-main">Subtropical Storm Nicole</span> Atlantic subtropical storm in 2004

Subtropical Storm Nicole was the first subtropical storm to receive a name using the standard hurricane name list that did not become a tropical cyclone. The fifteenth tropical or subtropical cyclone and fourteenth named storm of the 2004 Atlantic hurricane season, Nicole developed on October 10 near Bermuda from a broad surface low that developed as a result of the interaction between an upper level trough and a decaying cold front. The storm turned to the northeast, passing close to Bermuda as it intensified to reach peak winds of 50 mph on October 11. Deep convection developed near the center of the system as it attempted to become a fully tropical cyclone. However, it failed to do so and was absorbed by an extratropical cyclone late on October 11.

<span class="mw-page-title-main">Extratropical cyclone</span> Type of cyclone

Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are low-pressure areas which, along with the anticyclones of high-pressure areas, drive the weather over much of the Earth. Extratropical cyclones are capable of producing anything from cloudiness and mild showers to severe gales, thunderstorms, blizzards, and tornadoes. These types of cyclones are defined as large scale (synoptic) low pressure weather systems that occur in the middle latitudes of the Earth. In contrast with tropical cyclones, extratropical cyclones produce rapid changes in temperature and dew point along broad lines, called weather fronts, about the center of the cyclone.

<span class="mw-page-title-main">Subtropical Storm Andrea (2007)</span> Atlantic subtropical storm in 2007

Subtropical Storm Andrea was the first named storm to form in May in the Atlantic Ocean in 26 years. Andrea caused large waves and tropical-storm force winds along the southeast coast of the United States. The first named storm and the first subtropical cyclone of the 2007 Atlantic hurricane season, Andrea developed out of a non-tropical low on May 9 about 150 miles (240 km) northeast of Daytona Beach, Florida, three weeks before the official start of the season. After encountering dry air and strong vertical wind shear, Andrea weakened to a subtropical depression on May 10 while remaining nearly stationary, and the National Hurricane Center discontinued advisories early on May 11. Andrea's remnant was subsequently absorbed into another extratropical storm on May 14. Andrea was the first pre-season storm to develop since Tropical Storm Ana in April 2003. Additionally, the storm was the first Atlantic named storm in May since Tropical Storm Arlene in 1981.

<span class="mw-page-title-main">2006 Central Pacific cyclone</span> Unusual cyclonic formation in the Pacific Ocean

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<span class="mw-page-title-main">Climate of Hawaii</span>

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Hybrid low may refer to a number of different meteorological depressions:

<span class="mw-page-title-main">Glossary of tropical cyclone terms</span>

The following is a glossary of tropical cyclone terms.

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<span class="mw-page-title-main">October 2017 North American storm complex</span> Meteorological bomb that affected United States and Canada

The October 2017 North American storm complex was a major explosive cyclogenesis storm, also called bomb, in the Northeastern United States and Atlantic Canada from October 29–31, 2017. Forming from an extratropical cyclone on October 29 the system moved rapidly up the East Coast of the United States, bombing out with a minimum pressure of 975 millibars (28.8 inHg) on October 30. It brought heavy rain and extremely strong winds, and power outages, over 1.3 million customers being without power in the Northeast. Hurricane-force wind gusts resulted in downed trees, power lines, and widespread damage to buildings. The number of power outages in the state of Maine surpassed the Ice Storm of 1998.

References

  1. 1 2 Climate of Hawaii Archived 2008-03-14 at the Wayback Machine on Western Regional Center web site
  2. lookup of "Kona" Archived 2012-12-28 at archive.today on Hawaiian Dictionary
  3. Pennsylvania State University. Subtropical cyclones. Archived 2010-07-01 at the Wayback Machine Retrieved on 2009-05-22.
  4. Otkin, J. A., and J. E. Martin. (2004). A synoptic-climatology of the subtropical Kona storm. Mon. Wea. Rev., 132, 1502-1517. Download PDF
  5. Jan TenBruggencate. Rain-making Kona systems behind persistent downpours Honolulu Advertiser, retrieved on 2009-05-22
  6. Steven Businger and Thomas Birchard, Jr. A Bow Echo and Severe Weather Associated with a Kona Low in Hawaii. Retrieved on 2007-05-22.
  7. Steven Businger. Kona Lows in Hawaii. Archived 2007-06-18 at the Wayback Machine Retrieved on 2007-05-22.
  8. Ian Morrison and Steven Businger. Synoptic Structure and evolution of a Kona low Retrieved on 2009-05-22.
  9. Pacific Disaster Center. High Wind in Hawaii. Archived 2007-04-24 at the Wayback Machine Retrieved on 2007-05-22.
  10. 1 2 3 . Unusual Winter Storm, Hawaii. Retrieved on 2007-11-23.
  11. "Lane could be the largest Maui storm since one in 1980".
  12. "Major Power Outage in Honolulu as Obama Visits" in Time Magazine, December 27, 2008