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Hurricane Florence (1994)
Encyclopedia
Hurricane Florence was a strong, late season hurricane
that remained out over the open waters of the Central Atlantic
for nearly a week, before being absorbed into a large extratropical cyclone
. With peak winds of 110 mph (175 km/h) and a minimum pressure of 972 mbar
(hPa
; 28.71 inHg), Florence was the strongest storm of the 1994 Atlantic hurricane season
. Florence developed out of an area of low pressure
associated with a stalled frontal system
located 1,150 mi (1,850 km) east-southeast of Bermuda
in late October. The system gradually became better organized and was classified a subtropical depression
on November 2. The storm intensified into a subtropical storm shortly thereafter before weakening to a depression the next day.
After gaining tropical characteristics throughout most of the day on November 3, the storm was designated Tropical Depression Eleven. The depression quickly strengthened into Tropical Storm Florence, the sixth named storm of the season. The storm briefly underwent rapid intensification
, strengthening into a hurricane, before leveling out as a Category 1 hurricane. Florence was subsequently upgraded to a Category 2 hurricane on November 7. However, a large extratropical cyclone located to the north caused the hurricane to rapidly accelerate, with forward speeds reaching 58 mph (93 km/h). By the next day, Florence lost its identity, while still producing hurricane-force winds, as it was absorbed by the extratropical cyclone.
located 1,150 mi (1,850 km) east-southeast of Bermuda
. The low gradually detached from the front and began developing convective banding features
. The system was not fully tropical as the strongest winds were recorded a couple hundred miles from the center, leading to the system being classified a subtropical cyclone on the morning of November 2. Minor intensification followed shortly after and the subtropical depression was upgraded to a subtropical storm. This was based on ship reports of 40 mph (65 km/h) sustained winds associated with the system. By November 3, the storm became slightly disorganized and was downgraded to a subtropical depression. By the afternoon, the subtropical system began to undergo a transition from a subtropical system to tropical system
. Later that day, the storm was classified Tropical Depression Eleven while located 875 mi (1,400 km) east-southeast of Bermuda. The depression was moving towards the northwest at 8 mph (13 km/h) and the same general motion was expected as a large upper-level low
situated over the system was forecast to move towards the northeast, leading to Eleven moving around the periphery of the low.
The depression was upgraded to Tropical Storm Florence the next morning. However, outflow from the storm remained poor as the upper-level low was still interacting with the center of Florence and the storm was still not completely tropical but there was slight improvement. By the afternoon of November 4, Florence completed its transition into a tropical cyclone and deep convection developed, causing the storm to quickly intensity; with winds increasing by 20 mph (30 km/h) in a 6 hour time period. The trend in intensification was forecast to continue and Florence was forecast to become the second hurricane of the season within 12 hours. Late on November 4, Florence was upgraded to a hurricane as a solid area of deep convection developed around the center of circulation. An eye feature
also appeared on infrared satellite but was not associated with significant strengthening. Florence slowly intensified as the eye persisted and the structure slightly improved. By the morning of November 6, the eye became less defined and the cloud tops around it warmed. The storm also shifted its foreword motion northward as the trough located to the southeast began to move towards the east, moving the steering currents with it. As the low moved further to the east, steering currents in the area of Florence weakened, leading to the storm stalling late on November 6.
By the morning of November 7, the eye began to reappear and the storm turned towards the northwest and the foreword motion began to rapidly increase. Later that morning, Florence had developed a large, 35 to 40 mi (55 to 65 km/h) wide eye and the foreword motion continued to increase. The intensification continued and by the afternoon hours, Florence was upgraded to a Category 2 hurricane with winds of 100 mph (155 km/h). A strong extratropical cyclone located to the north of Florence was causing the storm to move towards the northwest at a rapid pace of 30 mph (48 km/h). Operationally, Florence was reported to have peaked at that intensity, but post season analysis determined that the storm reached its peak intensity just short of major hurricane—a storm with winds of 111 mph (178 km/h) or higher—status late on November 7. By the morning of November 8, Florence weakened slightly to Category 1 status. The large system to the north continued to cause Florence to move at 58 mph (93 km/h). Since the storm was very close to a cold front
, Florence was expected to rapidly transition into an extratropical cyclone. Later that morning, Florence was absorbed into the extratropical cyclone while still maintaining hurricane-force winds.
were issued, and the storm was never forecast to strike land.
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...
that remained out over the open waters of the Central Atlantic
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...
for nearly a week, before being absorbed into a large extratropical cyclone
Extratropical cyclone
Extratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
. With peak winds of 110 mph (175 km/h) and a minimum pressure of 972 mbar
Bar (unit)
The bar is a unit of pressure equal to 100 kilopascals, and roughly equal to the atmospheric pressure on Earth at sea level. Other units derived from the bar are the megabar , kilobar , decibar , centibar , and millibar...
(hPa
Pascal (unit)
The pascal is the SI derived unit of pressure, internal pressure, stress, Young's modulus and tensile strength, named after the French mathematician, physicist, inventor, writer, and philosopher Blaise Pascal. It is a measure of force per unit area, defined as one newton per square metre...
; 28.71 inHg), Florence was the strongest storm of the 1994 Atlantic hurricane season
1994 Atlantic hurricane season
The 1994 Atlantic hurricane seasonofficially began June 1, 1994, and officially ended November 30, 1994. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin....
. Florence developed out of an area of low pressure
Low pressure area
A low-pressure area, or "low", is a region where the atmospheric pressure at sea level is below that of surrounding locations. Low-pressure systems form under areas of wind divergence which occur in upper levels of the troposphere. The formation process of a low-pressure area is known as...
associated with a stalled frontal system
Weather front
A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses, fronts are depicted using various colored lines and symbols, depending on the type of front...
located 1,150 mi (1,850 km) east-southeast 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...
in late October. The system gradually became better organized and was classified a subtropical depression
Subtropical cyclone
A subtropical cyclone is a weather system that has some characteristics of a tropical and an extratropical cyclone. As early as the 1950s, meteorologists were unclear whether they should be characterized as tropical or extratropical cyclones. They were officially recognized by the National...
on November 2. The storm intensified into a subtropical storm shortly thereafter before weakening to a depression the next day.
After gaining tropical characteristics throughout most of the day on November 3, the storm was designated Tropical Depression Eleven. The depression quickly strengthened into Tropical Storm Florence, the sixth named storm of the season. The storm briefly underwent rapid intensification
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...
, strengthening into a hurricane, before leveling out as a Category 1 hurricane. Florence was subsequently upgraded to a Category 2 hurricane on November 7. However, a large extratropical cyclone located to the north caused the hurricane to rapidly accelerate, with forward speeds reaching 58 mph (93 km/h). By the next day, Florence lost its identity, while still producing hurricane-force winds, as it was absorbed by the extratropical cyclone.
Meteorological history
The origins of Florence can be traced back to an area of low pressure which developed in late October along a stationary frontStationary front
A stationary front is a boundary between two different air masses, neither of which is strong enough to replace the other. On a weather map, this is shown by an inter-playing series of blue spikes pointing one direction and red domes pointing the other. They tend to remain essentially in the same...
located 1,150 mi (1,850 km) east-southeast 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...
. The low gradually detached from the front and began developing convective banding features
Rainband
A rainband is a cloud and precipitation structure associated with an area of rainfall which is significantly elongated. Rainbands can be stratiform or convective, and are generated by differences in temperature. When noted on weather radar imagery, this precipitation elongation is referred to as...
. The system was not fully tropical as the strongest winds were recorded a couple hundred miles from the center, leading to the system being classified a subtropical cyclone on the morning of November 2. Minor intensification followed shortly after and the subtropical depression was upgraded to a subtropical storm. This was based on ship reports of 40 mph (65 km/h) sustained winds associated with the system. By November 3, the storm became slightly disorganized and was downgraded to a subtropical depression. By the afternoon, the subtropical system began to undergo a transition from a subtropical system to tropical system
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...
. Later that day, the storm was classified Tropical Depression Eleven while located 875 mi (1,400 km) east-southeast of Bermuda. The depression was moving towards the northwest at 8 mph (13 km/h) and the same general motion was expected as a large upper-level low
Cold-core low
A cold-core low, also known as a cold 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. It is a low pressure system which strengthens with height in accordance with the thermal wind relationship. These...
situated over the system was forecast to move towards the northeast, leading to Eleven moving around the periphery of the low.
The depression was upgraded to Tropical Storm Florence the next morning. However, outflow from the storm remained poor as the upper-level low was still interacting with the center of Florence and the storm was still not completely tropical but there was slight improvement. By the afternoon of November 4, Florence completed its transition into a tropical cyclone and deep convection developed, causing the storm to quickly intensity; with winds increasing by 20 mph (30 km/h) in a 6 hour time period. The trend in intensification was forecast to continue and Florence was forecast to become the second hurricane of the season within 12 hours. Late on November 4, Florence was upgraded to a hurricane as a solid area of deep convection developed around the center of circulation. An eye feature
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...
also appeared on infrared satellite but was not associated with significant strengthening. Florence slowly intensified as the eye persisted and the structure slightly improved. By the morning of November 6, the eye became less defined and the cloud tops around it warmed. The storm also shifted its foreword motion northward as the trough located to the southeast began to move towards the east, moving the steering currents with it. As the low moved further to the east, steering currents in the area of Florence weakened, leading to the storm stalling late on November 6.
By the morning of November 7, the eye began to reappear and the storm turned towards the northwest and the foreword motion began to rapidly increase. Later that morning, Florence had developed a large, 35 to 40 mi (55 to 65 km/h) wide eye and the foreword motion continued to increase. The intensification continued and by the afternoon hours, Florence was upgraded to a Category 2 hurricane with winds of 100 mph (155 km/h). A strong extratropical cyclone located to the north of Florence was causing the storm to move towards the northwest at a rapid pace of 30 mph (48 km/h). Operationally, Florence was reported to have peaked at that intensity, but post season analysis determined that the storm reached its peak intensity just short of major hurricane—a storm with winds of 111 mph (178 km/h) or higher—status late on November 7. By the morning of November 8, Florence weakened slightly to Category 1 status. The large system to the north continued to cause Florence to move at 58 mph (93 km/h). Since the storm was very close to a cold front
Cold 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...
, Florence was expected to rapidly transition into an extratropical cyclone. Later that morning, Florence was absorbed into the extratropical cyclone while still maintaining hurricane-force winds.
Impact and naming
As Florence remained out over the open waters of the central Atlantic, no effects, damages, or fatalities were reported. No tropical storm watches or warningsTropical cyclone warnings and watches
Warnings and watches are two levels of alert issued by national weather forecasting bodies to coastal areas threatened by the imminent approach of a tropical cyclone of tropical storm or hurricane intensity. They are notices to the local population and civil authorities to make appropriate...
were issued, and the storm was never forecast to strike land.
See also
- Other storms of the same name
- List of storms in the 1994 Atlantic hurricane season