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Hurricane Lisa (2004)
Encyclopedia
Hurricane Lisa was a long-lived Cape Verde-type hurricane
in the 2004 Atlantic hurricane season
. It was the twelfth named storm, as well as the ninth and final hurricane of the season. Lisa formed on September 19 and spent nearly two weeks fluctuating between a tropical depression and a tropical storm while traversing the central Atlantic. It briefly became a hurricane on October 2 in the north Atlantic before weakening and becoming extratropical shortly afterward. It was never a threat to land.
that crossed the Africa
n coast on September 16. The wave slowly organized as it tracked south of Cape Verde
, and it organized enough to be declared Tropical Depression Thirteen on September 19 while to the southwest of Cape Verde. From the outset, the system was hindered by significant wind shear
from the southwest as a result of the outflow of Karl
to its west. Nonetheless, on the morning of September 20, the depression organized enough to become Tropical Storm Lisa with maximum sustained winds of 45 mph (70 km/h). A poorly defined eye
also began to develop at that time despite its relatively weak intensity.
Lisa continued to gradually intensify that afternoon and evening as shear briefly subsided. The lower shear allowed it to strengthen to a high-end tropical storm with 70 mph (110 km/h) winds and a central pressure of 990 mbar by the morning of on September 21, following an initial track slightly to the north of that of Karl in the central Atlantic. The intensity held at such for most of that day as Lisa tracked westward. However, as the storm dipped somewhat to the south into Karl's wake early on September 22, it began to weaken and become more disorganized due to increased shear. In addition, the poor organization made it prone to impacts from a second tropical disturbance to the east, which the NHC thought could develop into a tropical cyclone in itself or absorb Lisa. Lisa began interacting with the disturbance to its east that afternoon and continued to weaken.
The gradual weakening trend continued into September 23 as Lisa continued to absorb the adjacent disturbance amidst a high-shear environment. That afternoon, Lisa briefly weakened to a tropical depression before restrengthening to a tropical storm that evening as the shear moderated. The storm maintained its small but distinct low-level circulation as the other disturbance was absorbed by Lisa. At that point, Lisa began to make a turn to the northwest. The intensity fluctuated on September 24 between depression and storm strength as it tracked northwest. Early on September 25, the fluctuations ended and Lisa regained tropical storm intensity, while turning more to the north. The storm gradually gained strength late on September 25 and early in the morning of September 26, reaching a second peak of 65 mph (100 km/h) that morning as shear moderated. However, the combination of an increase in shear from the southwest and the cool wake of Karl to the north weakened Lisa once again. The trend continued into the afternoon of September 27, when Lisa levelled off as a low-end tropical storm. The intensity remained stable into the morning of September 28, as Lisa remained disorganized in a high-shear environment.
Despite the fact that conditions remained quite hostile for development, Lisa slowly intensified once again on the 28th. That afternoon, an eye began to reform as it tracked northward. Lisa approached hurricane intensity once again that evening, and held at 70 mph (110 km/h) throughout the day on September 29 as shear subsided somewhat and the sea surface temperatures remained favorable for development. Despite the favorable conditions at the time, Lisa did not strengthen into a hurricane at that time. Early on September 30, the storm began to weaken somewhat once again as it tracked once again into the cooler water left behind by Karl.
The weakening trend was short-lived, however. The eye feature redeveloped once again late on the 30th and Lisa began to restrengthen, despite cooler water as it tracked into higher latitudes, turning somewhat to the northeast due to a southwesterly flow ahead of a trough
. The storm strengthened back to just below hurricane intensity on the morning of October 1. Operationally, Lisa was upgraded to a hurricane that afternoon, however, a QuikSCAT
pass was re-analyzed and indicated that the surface winds were somewhat overestimated. Early on October 2, Lisa finally became a hurricane with 75 mph (120 km/h) at 40.3°N latitude, while racing northeastward over relatively cool waters of 74°F (23°C). After only 12 hours as a hurricane, Lisa weakened back to a tropical storm that afternoon and began to lose tropical characteristics in the north Atlantic over cool waters. The system continued to disorganize itself that evening and by early on October 3, Lisa was declared extratropical while still at tropical storm intensity. Shortly thereafter, the system was absorbed by a larger frontal zone.
and never threatened any land areas. No damage or fatalities were reported.
Cape Verde-type hurricane
A Cape Verde-type hurricane is an Atlantic hurricane that develops near the Cape Verde islands, off the west coast of Africa. The average hurricane season has about two Cape Verde-type hurricanes, which are usually the largest and most intense storms of the season because they often have plenty of...
in the 2004 Atlantic hurricane season
2004 Atlantic hurricane season
The 2004 Atlantic hurricane season officially began on June 1, 2004, and lasted until November 30, 2004. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin...
. It was the twelfth named storm, as well as the ninth and final hurricane of the season. Lisa formed on September 19 and spent nearly two weeks fluctuating between a tropical depression and a tropical storm while traversing the central Atlantic. It briefly became a hurricane on October 2 in the north Atlantic before weakening and becoming extratropical shortly afterward. It was never a threat to land.
Meteorological history
The system originated out of a tropical waveTropical wave
Tropical waves, easterly waves, or tropical easterly waves, also known as African easterly waves in the Atlantic region, are a type of atmospheric trough, an elongated area of relatively low air pressure, oriented north to south, which move from east to west across the tropics causing areas of...
that crossed the Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
n coast on September 16. The wave slowly organized as it tracked south of Cape Verde
Cape Verde
The Republic of Cape Verde is an island country, spanning an archipelago of 10 islands located in the central Atlantic Ocean, 570 kilometres off the coast of Western Africa...
, and it organized enough to be declared Tropical Depression Thirteen on September 19 while to the southwest of Cape Verde. From the outset, the system was hindered by significant wind shear
Wind shear
Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere...
from the southwest as a result of the outflow of Karl
Hurricane Karl (2004)
Hurricane Karl was a powerful Cape Verde-type hurricane during the 2004 Atlantic hurricane season. It was the eleventh named storm, eighth hurricane and sixth major hurricane of the 2004 season. Karl formed on September 16, originating from a strong tropical wave that emerged off of Africa. It...
to its west. Nonetheless, on the morning of September 20, the depression organized enough to become Tropical Storm Lisa with maximum sustained winds of 45 mph (70 km/h). A poorly 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...
also began to develop at that time despite its relatively weak intensity.
Lisa continued to gradually intensify that afternoon and evening as shear briefly subsided. The lower shear allowed it to strengthen to a high-end tropical storm with 70 mph (110 km/h) winds and a central pressure of 990 mbar by the morning of on September 21, following an initial track slightly to the north of that of Karl in the central Atlantic. The intensity held at such for most of that day as Lisa tracked westward. However, as the storm dipped somewhat to the south into Karl's wake early on September 22, it began to weaken and become more disorganized due to increased shear. In addition, the poor organization made it prone to impacts from a second tropical disturbance to the east, which the NHC thought could develop into a tropical cyclone in itself or absorb Lisa. Lisa began interacting with the disturbance to its east that afternoon and continued to weaken.
The gradual weakening trend continued into September 23 as Lisa continued to absorb the adjacent disturbance amidst a high-shear environment. That afternoon, Lisa briefly weakened to a tropical depression before restrengthening to a tropical storm that evening as the shear moderated. The storm maintained its small but distinct low-level circulation as the other disturbance was absorbed by Lisa. At that point, Lisa began to make a turn to the northwest. The intensity fluctuated on September 24 between depression and storm strength as it tracked northwest. Early on September 25, the fluctuations ended and Lisa regained tropical storm intensity, while turning more to the north. The storm gradually gained strength late on September 25 and early in the morning of September 26, reaching a second peak of 65 mph (100 km/h) that morning as shear moderated. However, the combination of an increase in shear from the southwest and the cool wake of Karl to the north weakened Lisa once again. The trend continued into the afternoon of September 27, when Lisa levelled off as a low-end tropical storm. The intensity remained stable into the morning of September 28, as Lisa remained disorganized in a high-shear environment.
Despite the fact that conditions remained quite hostile for development, Lisa slowly intensified once again on the 28th. That afternoon, an eye began to reform as it tracked northward. Lisa approached hurricane intensity once again that evening, and held at 70 mph (110 km/h) throughout the day on September 29 as shear subsided somewhat and the sea surface temperatures remained favorable for development. Despite the favorable conditions at the time, Lisa did not strengthen into a hurricane at that time. Early on September 30, the storm began to weaken somewhat once again as it tracked once again into the cooler water left behind by Karl.
The weakening trend was short-lived, however. The eye feature redeveloped once again late on the 30th and Lisa began to restrengthen, despite cooler water as it tracked into higher latitudes, turning somewhat to the northeast due to a southwesterly flow ahead of a trough
Trough (meteorology)
A trough is an elongated region of relatively low atmospheric pressure, often associated with fronts.Unlike fronts, there is not a universal symbol for a trough on a weather chart. The weather charts in some countries or regions mark troughs by a line. In the United States, a trough may be marked...
. The storm strengthened back to just below hurricane intensity on the morning of October 1. Operationally, Lisa was upgraded to a hurricane that afternoon, however, a QuikSCAT
QuikSCAT
The QuikSCAT is an earth-observing satellite that provided estimates of wind speed and direction over the oceans to National Oceanic and Atmospheric Administration and others. This "quick recovery" mission intended to replace the NASA Scatterometer , which failed in June 1997...
pass was re-analyzed and indicated that the surface winds were somewhat overestimated. Early on October 2, Lisa finally became a hurricane with 75 mph (120 km/h) at 40.3°N latitude, while racing northeastward over relatively cool waters of 74°F (23°C). After only 12 hours as a hurricane, Lisa weakened back to a tropical storm that afternoon and began to lose tropical characteristics in the north Atlantic over cool waters. The system continued to disorganize itself that evening and by early on October 3, Lisa was declared extratropical while still at tropical storm intensity. Shortly thereafter, the system was absorbed by a larger frontal zone.
Impact
Lisa remained in the open Atlantic OceanAtlantic 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...
and never threatened any land areas. No damage or fatalities were reported.
See also
- List of tropical cyclones
- List of Atlantic hurricane seasons
- 2004 Atlantic hurricane season2004 Atlantic hurricane seasonThe 2004 Atlantic hurricane season officially began on June 1, 2004, and lasted until November 30, 2004. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin...
- Timeline of the 2004 Atlantic hurricane seasonTimeline of the 2004 Atlantic hurricane seasonThe 2004 Atlantic hurricane season was notable as one of the deadliest and most costly Atlantic hurricane seasons on record. It officially began on June 1, 2004 and ended on November 30, although storm activity continued into December. This timeline documents tropical cyclone formations,...
External links
- NHC's Tropical Cyclone Report on Hurricane Lisa