Kona storms (also called Kona lows) are a type of seasonal

cyclone 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 (opposite to an ant ...

in the

Hawaiian Islands The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to nort ...

, usually formed in the winter from winds coming from the westerly "kona" (normally

leeward In geography and seamanship, windward () and leeward () are directions relative to the wind. Windward is ''upwind'' from the point of reference, i.e., towards the direction from which the wind is coming; leeward is ''downwind'' from the point o ...

) direction. They are mainly

cold core A cold-core low, also known as an upper level low or cold-core cyclone, is a cyclone aloft which has an associated cold pool of air residing at high altitude within the Earth's troposphere, without a weather front, frontal structure. It is a low ...

cyclones, which places them in the

extratropical 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 p ...

rather than the

subtropical cyclone A subtropical cyclone is a weather system that has some characteristics of both tropical cyclone, tropical and extratropical cyclones. As early as the 1950s, meteorologists were uncertain whether they should be characterized as Tropical 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 Rain is a form of precipitation where water drop (liquid), droplets that have condensation, condensed from Water vapor#In Earth's atmosphere, atmospheric water vapor fall under gravity. Rain is a major component of the water cycle and is res ...

hail Hail is a form of solid Precipitation (meteorology), precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailsto ...

storms,

flash flood A flash flood is a rapid flooding of low-lying areas: washes, rivers, dry lakes and depressions. It may be caused by heavy rain associated with a severe thunderstorm, hurricane, or tropical storm, or by meltwater from ice and snow. Flash f ...

s and their associated

landslide Landslides, also known as landslips, rockslips or rockslides, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, mudflows, shallow or deep-seated slope failures and debris flows. Landslides ...

s, high elevation

snow Snow consists of individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water througho ...

, high winds which result in large surf and swells, and

waterspout A waterspout is a rotating column of air that occurs over a body of water, usually appearing as a funnel-shaped cloud in contact with the water and a cumuliform cloud. There are two types of waterspout, each formed by distinct mechanisms. ...

Origin of term

Kona is a

Hawaiian language Hawaiian (', ) is a critically endangered Polynesian language of the Austronesian language family, originating in and native to the Hawaiian Islands. It is the native language of the Hawaiian people. Hawaiian, along with English, is an offi ...

term (related to similar words in other Polynesian languages) for the western (to southwestern) side of an island. The

Kona District Kona is a ''moku'' or district on the Big Island of Hawaii in the State of Hawaii, known for its Kona coffee and the Ironman World Championship Triathlon. In the administration of Hawaii County, the ''moku'' of Kona is divided into North Kon ...

for example on the

Big Island of Hawaii Big or BIG may refer to: * Big, of great size or degree Film and television * ''Big'' (film), a 1988 fantasy-comedy film starring Tom Hanks * ''Big'', a 2023 Taiwanese children's film starring Van Fan and Chie Tanaka * '' Big!'', a Discover ...

still uses this name. Although normally dry and

, the traditional easterly (to northeasterly)

tradewinds The trade winds or easterlies are permanent east-to-west prevailing winds that flow in the Earth's equatorial region. The trade winds blow mainly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere ...

slacken and reverse during one of these cyclones.

Character of the cyclones

Once termed as

s, 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

s. However, they generally share the subtropical cyclone characteristic of losing their associated

weather fronts A weather front is a boundary separating air masses for which several characteristics differ, such as air density, wind, temperature, and humidity. Disturbed and unstable weather due to these differences often arises along the boundary. For in ...

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. 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.Climate of Hawaii
on Western Regional Center web site

Frequency and effects

While some winters occur without a single Kona storm, other winters see a high of four or five. Hawaii typically experiences two to three annually between October and April.Steven Businger and Thomas Birchard, Jr
A Bow Echo and Severe Weather Associated with a Kona Low in Hawaii.
Retrieved on 2007-05-22. The cyclone events for Hawaii can be long-lived, affecting the state for a week or more.Steven Businger
Kona Lows in Hawaii.
Retrieved on 2007-05-22. 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.

Kona winds

Kona winds are associated with cyclones with central pressures below 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.

Examples

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.

Retrieved on 2007-11-23. 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. 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 on Lahaina Roads, Maui. Haiku, on the windward coast of Maui, experienced a wind gust of . On the high mountain summits of the Big Island and Maui, winds of over were recorded. Damage from the storm was estimated at between $25 and 35 million (in 1980 dollars). 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 Barack Hussein Obama II (born August 4, 1961) is an American politician who was the 44th president of the United States from 2009 to 2017. A member of the Democratic Party, he was the first African American president in American history. O ...

was visiting."Major Power Outage in Honolulu as Obama Visits"
in Time Magazine, December 27, 2008 In December 2010, a Kona storm became fully subtropical and eventually became Tropical Storm Omeka.

In popular culture

The fourth episode of the sixth season of

Magnum, P.I. ''Magnum, P.I.'' is an American crime drama television series starring Tom Selleck as Thomas Magnum, a private investigator (P.I.) living on Oahu, Hawaii. The series ran from December 11, 1980, to May 1, 1988, during its first-run broadcast on ...

is entitled "The Kona Winds."

References

{{DEFAULTSORT:Kona Storm Types of cyclone Weather events in Hawaii Storm Extratropical cyclones Subtropical cyclones