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Hurricane Bonnie (1992)
Encyclopedia
Hurricane Bonnie was a long-lived storm in the 1992 Atlantic hurricane season
. It was the third tropical storm
(including the April subtropical storm) and second hurricane of the 1992 season. Bonnie formed at high latitudes in the central Atlantic on September 17. Devoid of any real steering currents for much of its lifespan, it was nearly stationary for over a week in the central Atlantic Ocean
. On September 27, it began to slowly track east and northeast towards the Azores
. Just before becoming extratropical, it affected the Azores on September 30, although no damage was reported.
that moved off the U.S. East Coast
on September 11. The front moved gradually off the coast and into the subtropical Atlantic Ocean
before becoming stationary just east of Bermuda
on September 15. Over the next two days, the cloud cover slowly detached itself from the front and form into a tropical low in its own right. On the afternoon of September 17, the system was organized enough to be declared Tropical Depression Four.
The depression organized steadily that evening and into the morning of September 18. It was upgraded to Tropical Storm Bonnie early on the 18th and it began to move slowly to the northeast. Like most storms that develop in higher latitudes, Bonnie was embedded in a larger-scale cyclonic circulation at first, which minimized shear (allowing it to develop) and provided weak steering currents. The low shear allowed Bonnie to rapidly develop
and a small but well-defined eye
formed late that morning. The storm was upgraded to Hurricane Bonnie early that afternoon while meandering in the open ocean. The intensification rate slowed down after becoming a hurricane. In addition, Bonnie began to slowly move more to the northeast on September 19 as steering currents slowly developed. Bonnie strengthened into a Category 2 hurricane on the Saffir-Simpson hurricane scale
that morning as well, peaking at 105 mph (165 km/h) with a 970 mbar central pressure. The general track and intensity maintained itself throughout the day and into September 20, when the eye became less distinct and Bonnie weakened slightly, although remaining a Category 2 hurricane. Early on September 21, the eye became better defined once again and Bonnie restrengthened slightly while continuing its slow northeast motion. That afternoon, the storm gradually strengthened some more and reached its peak intensity of 110 mph (175 km/h) and a central pressure of 965 mbar, just under Category 3 intensity. Bonnie maintained its strength through the evening and into the early morning of September 22, when it began to weaken very gradually and level off. Bonnie also began to turn more eastward at that point before it became held up by a blocking mid-latitude ridge of high pressure
, which stalled the motion.
Bonnie remained virtually stationary until the morning of September 23 when it drifted very slowly to the west-southwest in response to the ridge. It also began to gradually weaken as the low-level center became exposed and the storm became poorly organized. Convection also diminished, and on the afternoon of September 24, Bonnie was downgraded to a tropical storm as it drifted over cooler waters. Bonnie continued to lose most of its deep convection during the day on September 25 as it began to make a turn back around to the south. That evening, Bonnie was downgraded to a tropical depression.
The weakening trend ended early on September 26 and Bonnie regained tropical storm status that afternoon as deep convection re-established itself. Bonnie continued its change in direction, turning to the southeast at this point as it slowly redeveloped despite being in a high-shear environment. It had also briefly showed signs of becoming extratropical on September 27 as it made the turn to the northeast as a weak tropical storm, and was operationally declared extratropical at that point until the afternoon of September 28. During that period, Bonnie actually strengthened back into a high-end tropical storm. Bonnie roughly followed Hurricane Charley's path towards the Azores thereafter. The storm became entrenched in an environment with greater wind shear, although it only weakened slightly on September 29 as it accelerated towards the northeast. The storm crossed over the Azores on September 30 as a strong tropical storm with 65 mph (100 km/h) winds. After that, Bonnie quickly lost its tropical characteristics and was declared extratropical late that afternoon, just east of the Azores. The extratropical low drifted back to the southwest in a clockwise loop, actually approaching the Azores once again while dissipating. It dissipated on October 2.
only four days after Charley, it resulted in tropical storm-force winds across much of the island chain. Lajes Air Base
reported sustained winds of 40 mph (64 km/h) with gusts to 59 mph (94 km/h). No damage or fatalities were reported.
1992 Atlantic hurricane season
The 1992 Atlantic hurricane season had one of the latest dates on record for the first named storm. The season officially began on June 1, 1992, and lasted until November 30, 1992. It was the least active hurricane season in nine years due to a strong El Niño...
. It was the third tropical storm
Tropical cyclone
A tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturated air rises, resulting in condensation of water vapor...
(including the April subtropical storm) and second hurricane of the 1992 season. Bonnie formed at high latitudes in the central Atlantic on September 17. Devoid of any real steering currents for much of its lifespan, it was nearly stationary for over a week in the central Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
. On September 27, it began to slowly track east and northeast towards the Azores
Azores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
. Just before becoming extratropical, it affected the Azores on September 30, although no damage was reported.
Meteorological history
The origins of the system was a cold frontCold front
A cold front is defined as the leading edge of a cooler mass of air, replacing a warmer mass of air.-Development of cold front:The cooler and denser air wedges under the less-dense warmer air, lifting it...
that moved off the U.S. East Coast
East Coast of the United States
The East Coast of the United States, also known as the Eastern Seaboard, refers to the easternmost coastal states in the United States, which touch the Atlantic Ocean and stretch up to Canada. The term includes the U.S...
on September 11. The front moved gradually off the coast and into the subtropical Atlantic Ocean
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
before becoming stationary just east of Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
on September 15. Over the next two days, the cloud cover slowly detached itself from the front and form into a tropical low in its own right. On the afternoon of September 17, the system was organized enough to be declared Tropical Depression Four.
The depression organized steadily that evening and into the morning of September 18. It was upgraded to Tropical Storm Bonnie early on the 18th and it began to move slowly to the northeast. Like most storms that develop in higher latitudes, Bonnie was embedded in a larger-scale cyclonic circulation at first, which minimized shear (allowing it to develop) and provided weak steering currents. The low shear allowed Bonnie to rapidly develop
Rapid deepening
Rapid deepening, also known as rapid intensification, is a meteorological condition that occurs when the minimum sea-level atmospheric pressure of a tropical cyclone decreases drastically in a short period of time. The National Weather Service describes rapid deepening as a decrease of...
and a small but well-defined eye
Eye (cyclone)
The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the second most severe weather of a cyclone...
formed late that morning. The storm was upgraded to Hurricane Bonnie early that afternoon while meandering in the open ocean. The intensification rate slowed down after becoming a hurricane. In addition, Bonnie began to slowly move more to the northeast on September 19 as steering currents slowly developed. Bonnie strengthened into a Category 2 hurricane on the Saffir-Simpson hurricane scale
Saffir-Simpson Hurricane Scale
The Saffir–Simpson Hurricane Scale , or the Saffir–Simpson Hurricane Wind Scale , classifies hurricanes — Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms — into five categories distinguished by the intensities of their sustained winds...
that morning as well, peaking at 105 mph (165 km/h) with a 970 mbar central pressure. The general track and intensity maintained itself throughout the day and into September 20, when the eye became less distinct and Bonnie weakened slightly, although remaining a Category 2 hurricane. Early on September 21, the eye became better defined once again and Bonnie restrengthened slightly while continuing its slow northeast motion. That afternoon, the storm gradually strengthened some more and reached its peak intensity of 110 mph (175 km/h) and a central pressure of 965 mbar, just under Category 3 intensity. Bonnie maintained its strength through the evening and into the early morning of September 22, when it began to weaken very gradually and level off. Bonnie also began to turn more eastward at that point before it became held up by a blocking mid-latitude ridge of high pressure
High pressure area
A high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
, which stalled the motion.
Bonnie remained virtually stationary until the morning of September 23 when it drifted very slowly to the west-southwest in response to the ridge. It also began to gradually weaken as the low-level center became exposed and the storm became poorly organized. Convection also diminished, and on the afternoon of September 24, Bonnie was downgraded to a tropical storm as it drifted over cooler waters. Bonnie continued to lose most of its deep convection during the day on September 25 as it began to make a turn back around to the south. That evening, Bonnie was downgraded to a tropical depression.
The weakening trend ended early on September 26 and Bonnie regained tropical storm status that afternoon as deep convection re-established itself. Bonnie continued its change in direction, turning to the southeast at this point as it slowly redeveloped despite being in a high-shear environment. It had also briefly showed signs of becoming extratropical on September 27 as it made the turn to the northeast as a weak tropical storm, and was operationally declared extratropical at that point until the afternoon of September 28. During that period, Bonnie actually strengthened back into a high-end tropical storm. Bonnie roughly followed Hurricane Charley's path towards the Azores thereafter. The storm became entrenched in an environment with greater wind shear, although it only weakened slightly on September 29 as it accelerated towards the northeast. The storm crossed over the Azores on September 30 as a strong tropical storm with 65 mph (100 km/h) winds. After that, Bonnie quickly lost its tropical characteristics and was declared extratropical late that afternoon, just east of the Azores. The extratropical low drifted back to the southwest in a clockwise loop, actually approaching the Azores once again while dissipating. It dissipated on October 2.
Impact
When Bonnie passed over the AzoresAzores
The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
only four days after Charley, it resulted in tropical storm-force winds across much of the island chain. Lajes Air Base
Lajes Field
Lajes Field or Lajes Air Base , officially designated Air Base No. 4 , is a multi-use air field, home to the Portuguese Air Force Base Aérea Nº4 and Azores Air Zone Command , a United States Air Force detachment , and a regional air passenger terminal located near Lajes...
reported sustained winds of 40 mph (64 km/h) with gusts to 59 mph (94 km/h). No damage or fatalities were reported.
See also
- Other storms of the same name
- Timeline of the 1992 Atlantic hurricane seasonTimeline of the 1992 Atlantic hurricane seasonThe 1992 Atlantic hurricane season was a below-average season that produced six named tropical cyclones. The season officially started on June 1, 1992 and finished on November 30; however, Subtropical Storm One formed outside the official timeline on April 21...
External links
- NHC's Preliminary Report on Hurricane Bonnie