Hurricane Cosme (2007)

From Wikipedia, the free encyclopedia

Hurricane Cosme

Category 1 Hurricane (SSHS)
Hurricane Cosme near peak intensity
Formed	July 14, 2007
Dissipated	July 23, 2007
Highest winds	75 mph (120 km/h) (1-minute sustained)
Lowest pressure	987 mbar (hPa; 29.16 inHg)
Fatalities	None reported
Damage	Minimal
Areas affected	Hawaii
Part of the 2007 Pacific hurricane season

Hurricane Cosme was a minimal hurricane that threatened Hawai'i in mid-July. The sixth tropical cyclone, third named storm and first hurricane of the 2007 Pacific hurricane season, the hurricane originated from a tropical wave that emerged off the coast of Africa on June 27 and tracked westward before emerging in the eastern Pacific. The wave organized, and was classified as a tropical depression on July 14, a tropical storm on July 15, and a hurricane on July 16. Cosme reached peak intensity as a Category 1 hurricane, but quickly weakened due to cooler waters. Steadily decreasing in strength, the storm was downgraded to a tropical depression before passing to the south of the Hawaiian Islands. The depression crossed into the Central Pacific and degenerated into a remnant low by July 23. Because Cosme stayed far from land, effects were mostly minor. Swells up to 9 ft (2.7 m) and up to 6.94 in (176 mm) of rainfall were reported, in addition to wind gusts of 40 mph (64 km/h). No fatalities or injuries were reported, and only minimal damage occurred.

Contents 1 Storm history 2 Preparations and impact 3 See also 4 References

[edit] Storm history

The origins of Cosme can be traced back to a tropical wave that left the coast of Africa on June 27, 2007. Due to a lack of associated convection, the wave was difficult to track across the Atlantic Ocean and Caribbean Sea. It is estimated that the wave emerged into the Pacific Ocean on July 8. Because the system was embedded within the Intertropical Convergence Zone (ITCZ), development was initially slow. However, when it separated from the ITCZ on July 13, it increased in convective organization, and was classified as Tropical Depression Six-E about midway between Mexico and Hawaii.^[1] It tracked westward at 12 mph (19 km/h) under the steering currents of a deep tropical easterly flow. Although wind shear was generally light, ocean temperatures were only marginal for tropical cyclone intensification.^[2][3] The depression was still in its formative stages, causing difficulty in locating the exact center of circulation. By July 14, convection had steadily decreased,^[4] and its movement was initially uncertain due to its presence within a larger system.^[5] Early on July 15 the overall cloud pattern improved,^[6] and at 1800 UTC it was upgraded to Tropical Storm Cosme.^[1]

Shortly after attaining tropical storm status, the formerly broad circulation consolidated as banding features increased.^[7] The inner core gradually condensed and tightened, as indicated by an AMSR-E overpass.^[8] On July 16 an eye began to form and Cosme intensified to attain winds of 65 mph (105 km/h). Tracking northwest towards a weakness in the mid-level ridge,^[9] the cyclone continued to intensify and was upgraded to Hurricane Cosme late on July 16, about 1,600 mi (2,600 km) east of Hilo, Hawaii.^[1] The hurricane reached peak intensity of 75 mph (121 km/h), although due to cooler waters it quickly weakened to a tropical storm^[1] as the eye became ragged and cloud-filled and convective cloud tops warmed slightly.^[10]

Initially, Cosme was predicted to make landfall on Hawaii as a tropical storm.^[11] By July 17, the cloud pattern had deteriorated, and its winds decreased to 46 mph (74 km/h).^[12] The center subsequently became exposed, with just a few thunderstorms confined to the southwest portion of the storm as it began to accelerate to the west.^[13] As easterly vertical wind shear increased, convection temporarily reformed in a concentrated area southwest of the center.^[14] As Cosme reached steadily cooler water temperatures, it was downgraded to a tropical depression late on July 18 about 900 mi (1,400 km) southeast of Hilo, Hawaii; at around the same time, the storm entered the forecast responsibility of the Central Pacific Hurricane Center.^[1] Tracking westward at 14 mph (23 km/h), maximum sustained winds were 35 mph (56 km/h) with localized higher gusts.^[15] Gradually weakening, Tropical Depression Cosme passed south of the Hawaiian islands on July 20 with a minimum central pressure of 1010 mbar.^[16] On July 22, the depression came within 180 mi (290 km) of Johnston Island,^[17] and later that day, it degenerated into a remnant low pressure system.^[1]

[edit] Preparations and impact

In anticipation of Cosme, the National Weather Service issued a flash flood watch for the island of Hawaii on July 20. Also, small craft advisories were in effect for Maui and Hawaii^[18] in addition to wind advisories for summits in those locations.^[19] High surf advisories were also put into effect for coastal areas.^[20] The Hawaii County Civil Defense prepared for the storm by planning for increases in emergency response personnel and opening of evacuation centers.^[21] County crews worked to clean out drains and culverts to prevent flooding.^[20]

Because the depression stayed far from land, the effects were mostly minor and little damage was reported.^[1] A strong trade wind swell north of Cosme generated waves up to 9 ft (2.7 m) high.^[22] Rain bands produced up to 6.94 in (176 mm) of rainfall,^[23] causing small stream and drainage ditch flooding, and ponding on roadways in portions of Hilo, Puna, and Kau districts on the windward side of the Island of Hawaii.^[24] The rainfall helped to relieve a persistent drought which had existed for several months.^[25] Wind gusts reached 40 mph (64 km/h) in southern portions of Hawaii, causing no known damage.^[25]

[edit] See also

• List of Hawaii hurricanes
• Other tropical cyclones named Cosme

[edit] References