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Tropical Storm Henri was the eighth named tropical cyclone in the 2009 Atlantic hurricane season. A weak and disorganized cyclone, Henri formed on October 6 from a tropical wave and moved northwestward for most of its life. Persistent wind shear prevented it from intensifying beyond a weak tropical storm. After peaking in strength on October 7 it began to deteriorate, and weakened to a remnant low on October 8. Henri remained over open waters and did not affect any land areas, although the storm is noted for its sudden formation from a disturbance that was initially not expected to develop.

Meteorological history

Template:Storm path Henri's origins are traced back to a tropical wave which emerged from the western coast of Africa on October 1, 2009. As it tracked westward across the Atlantic Ocean, it produced intermittent showers and thunderstorms.[1] By October 4, the system had become accompanied by a large area of disorganized convective activity, and the National Hurricane Center remarked upon the possibility for tropical cyclone development.[2] While located about 950 mi (Template:Convert/km) east of the Windward Islands on October 5, the system became better organized and more well-defined as it continued generally towards the west.[3] Later that day, a broad area of low pressure formed in association with the wave.[4] Although the strong thunderstorm activity was displaced to the east of the center of circulation, the disturbance had become a tropical depression around 0000 UTC on October 6 while located about 775 mi (Template:Convert/km) east of the Lesser Antilles.[1] Operationally, however, the storm was not designated a tropical cyclone until later that day, when it was immediately declared a tropical storm.[5]

Affected by strong southwesterly wind shear, Henri remained weak and disorganized, and its center continued was still located on the western edge of the main area of convection.[1] Moving northwestward under the steering currents of a mid-level subtropical ridge to the north, the cyclone strengthened slightly late on October 6, but it was still anticipated to dissipate within 48 hours.[6] By early the next morning, convection increased in intensity and coverage around the center, and Henri reached its peak intensity with winds of 50 mph (85 km/h) and a minimum central pressure of 1005 mbar (hPa; 29.68 inHg) at around 0600 UTC.[1]

The period of development was short-lived, however: the cyclone quickly began to deteriorate once again as the vertical wind shear grew stronger,[1] and the center of circulation had become further detached from the strongest thunderstorm activity.[7] The storm continued to weaken, and on October 8, it was downgraded to a tropical depression.[1] The depression remained disarranged, and satellite imagery suggested that multiple low-level vortices were present within the more broad circulation.[8] Just 12 hours after degenerating into a depression, the cyclone decreased to a remnant area of low pressure. The storm's remnants continued northwestward for the next day, until high pressure over the western Atlantic turned the system southwestward; the remains of Henri dissipated near Hispaniola several days later.[1]

Impact and forecasting

As a tropical cyclone, Henri remained over open waters of the Atlantic and did not impact any land areas. As a result, no deaths or damages occurred in association with the storm, and no tropical cyclone watches and warnings were issued. Additionally, no ships recorded tropical storm-force winds from the storm.[1] In general, the storm's formation was poorly forecast. Although the possibility of tropical development was mentioned 36 hours prior to Henri's designation, it was initially assessed as having less than a 30% of strengthening into a depression.[9]

See also




External links

Template:Commons category

Template:2009 Atlantic hurricane season buttons


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