Hurricane Lisa (2004)

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Hurricane Lisa
Category 1 hurricane (SSHS)
Hurricane Lisa churning the Atlantic on October 2, 2004

Hurricane Lisa churning the Atlantic on October 2, 2004
Formed September 19, 2004
Dissipated October 3, 2004
Highest
winds
75 mph (120 km/h) (1-minute sustained)
Lowest pressure 987 mbar (hPa; 29.16 inHg)
Fatalities None
Damage None
Areas
affected		 No land areas
Part of the
2004 Atlantic hurricane season

Hurricane Lisa was a long-lived Cape Verde-type hurricane in the 2004 Atlantic hurricane season. The tropical cyclone was only briefly a hurricane; it spent most of its lifetime as a tropical storm or tropical depression. It was the twelfth named storm and the ninth (and final) hurricane of the 2004 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 finally became a hurricane on October 2 in the north Atlantic before weakening and becoming extratropical shortly afterward. It was never a threat to land.

Contents

[edit] Storm history

Storm path
Storm path

The system originated out of a tropical wave that crossed the African 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.[1] 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.[2] 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).[1] A poorly-defined eye also began to develop at that time despite its relatively weak intensity.[3]

Lisa continued to gradually intensify that afternoon and evening as shear briefly subsided.[4] 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.[1] 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. [5] Lisa began interacting with the disturbance to its east that afternoon and continued to weaken.[6]

The gradual weakening trend continued into September 23 as Lisa continued to absorb the adjacent disturbance amidst a high-shear environment.[7] 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.[1] The intensity fluctuated on September 24 between depression and storm strength as it tracked northwest.[8] Early on September 25, the fluctations ended and Lisa regained tropical storm intensity, while turning more to the north.[1]

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.[1] However, the combination of an increase in shear from the southwest and the cool wake of Karl to the north weakened Lisa once again.[9] 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.[10]

Tropical Storm Lisa on September 29
Tropical Storm Lisa on September 29

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.[11] 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.[12] 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.[13][1]

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.[14] The storm strengthened back to just below hurricane intensity on the morning of October 1.[1] Operationally, Lisa was upgraded to a hurricane that afternoon[15], 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).[16][1]

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.[1]

[edit] Impact, records and naming

Lisa remained in the open Atlantic Ocean and never threatened any land areas. No damage or fatalities were reported.[1]

Lisa spent 11¾ days as a tropical cyclone between it becoming a tropical storm on September 20 and becoming a hurricane on October 2, which is the longest time ever between becoming a tropical storm and a hurricane. Hurricane Dennis of the 1981 Atlantic hurricane season took longer overall but dropped to a tropical wave before regenerating. Lisa's total development time from tropical depression to hurricane, at 12½ days, is second only to Hurricane Josephine of the 1990 Atlantic hurricane season.[17]

It was the second time that the name Lisa was used; the first time being in the 1998 Atlantic hurricane season. Due to the lack of any impacts, the name was not retired and is scheduled to be used again in the 2010 Atlantic hurricane season.

[edit] References

  1. ^ a b c d e f g h i j k National Hurricane Center (2004). Tropical Cyclone Report: Hurricane Lisa. NOAA. Retrieved on 2006-03-18.
  2. ^ National Hurricane Center (2004). Tropical Depression Thirteen Discussion #1. NOAA. Retrieved on 2006-12-20.
  3. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #4. NOAA. Retrieved on 2006-12-20.
  4. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #9. NOAA. Retrieved on 2006-12-20.
  5. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #12. NOAA. Retrieved on 2006-12-20.
  6. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #13. NOAA. Retrieved on 2006-12-20.
  7. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #17. NOAA. Retrieved on 2006-12-20.
  8. ^ National Hurricane Center (2004). Tropical Depression Lisa Discussion #22. NOAA. Retrieved on 2006-12-20.
  9. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #31. NOAA. Retrieved on 2006-12-20.
  10. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #35. NOAA. Retrieved on 2006-12-20.
  11. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #37. NOAA. Retrieved on 2006-12-20.
  12. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #42. NOAA. Retrieved on 2006-12-20.
  13. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #45. NOAA. Retrieved on 2006-12-20.
  14. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #49. NOAA. Retrieved on 2006-12-20.
  15. ^ National Hurricane Center (2004). Tropical Storm Lisa Discussion #50. NOAA. Retrieved on 2006-12-20.
  16. ^ National Hurricane Center (2004). Hurricane Lisa Discussion #52. NOAA. Retrieved on 2006-12-20.
  17. ^ Atlantic Oceanography and Meteorological Laboratory (2006). Re-Analysis Project. NOAA. Retrieved on 2006-12-17.

[edit] See also

Tropical cyclones Portal

[edit] External links

Tropical cyclones of the 2004 Atlantic hurricane season
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Saffir-Simpson Hurricane Scale
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