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Hurricane Cristobal was a moderately strong Atlantic tropical cyclone that affected multiple landmasses from Puerto Rico to Iceland in late August and early September 2014. Slow to develop, and plagued by unfavorable wind shear for most of its life, the storm formed on August 23 near the Caicos Islands from a long-tracked tropical wave. Moving generally northward, Cristobal gradually intensified despite a ragged appearance on satellite imagery, and passed midway between Bermuda and North Carolina on August 27. While accelerating toward the northeast the next day, Cristobal achieved its peak strength as a Category 1 hurricane. A colder environment converted Cristobal into an extratropical cyclone on August 29, but it retained much of its strength as it sped across the northern Atlantic and struck Iceland on September 1. Before its classification as a tropical cyclone, the disturbance that would become Cristobal dropped heavy rainfall over Puerto Rico, locally reaching . Widespread flooding and scattered landslides affected the territory, with 19 major rivers exceeding minor flood stage. The system went on to douse the island of Hispaniola with torrential rains, leading to at least four drowning deaths in Haiti and the Dominican Republic. Floodwaters damaged or destroyed over 800 houses and temporarily isolated 23 communities in the Dominican Republic, while about 640 families were displaced in Haiti. Another person was killed by floodwaters in the Turks and Caicos. The hurricane generated strong surf and dangerous rip currents along the U.S. East Coast, killing two swimmers in Maryland and New Jersey and leading to large numbers of lifeguard rescues. Later, the extratropical remnants of Cristobal buffeted Iceland with heavy rain and gusty winds, causing flooding around the capital city of Reykjavík. ==Meteorological history== Hurricane Cristobal originated from a westward-tracking tropical wave which emerged from the western coast of Africa on August 14, accompanied for several days by an expanse of clouds. Some cyclonic turning was evident as the disturbance approached the Leeward Islands by August 21, but a Hurricane Hunters flight tasked with investigating the system did not reveal a strong circulation at the surface. The system failed to consolidate as it traversed Puerto Rico and Hispaniola, but on August 23, further reconnaissance data confirmed the formation of a tropical depression just south of the Caicos Islands. The nascent cyclone slowly moved north-northwestward toward a weakness in the subtropical ridge. Moderate wind shear in the area kept convection over the depression disorganized and outflow limited, and the storm only gradually intensified. The depression strengthened into Tropical Storm Cristobal at 06:00 UTC on August 24, while located just north of Mayaguana in the Bahamas,〔 but its structure was vertically tilted and suboptimally broad. Weak steering currents kept Cristobal's forward motion slow and erratic, and the storm remained heavily affected by shear, with most deep convection displaced from the center. On August 25, the system turned toward the north-northeast in response to a mid-level trough to the north.〔 Despite a ragged cloud pattern characterized by an exposed low-level center and a distinct lack of banding features, Cristobal intensified into a Category 1 hurricane at 00:00 UTC on August 26, as indicated by aircraft observations.〔 The newly upgraded hurricane headed along a general northward path, and for the next couple days, pockets of dry air kept prevented further intensification.〔 Convection fluctuated in intensity and coverage, and early on August 27 the National Hurricane Center remarked that "the satellite presentation resembles a subtropical cyclone". However, later that same day, the hurricane showed signs of increased development while located midway between Bermuda and Cape Hatteras, North Carolina. In particular, its cloud pattern became much more symmetric, and some cloud tops cooled to –70 °C (–95 °F).〔 Around the same time, Cristobal accelerated toward the northeast as it became embedded within the mid-latitude westerlies ahead of an advancing shortwave trough.〔 An area of relatively warm cloud tops at the center of a central dense overcast gave way to an eye feature evident on visible satellite imagery on August 28. Rapidly gaining latitude, Cristobal reached its peak intensity at 18:00 UTC, with winds of 85 mph (140 km/h), roughly due south of Halifax, Nova Scotia.〔 Shortly thereafter, the hurricane began to degrade as it moved over significantly colder waters and began to encounter further dry air, signalling the beginning of its transition to an extratropical cyclone. Cristobal's circulation soon began to interact with a frontal boundary, and deep convection became distanced well to the north of the center. Consequently, the hurricane lost its tropical identity by 12:00 UTC on August 29, just north of 44°N.〔 Baroclinic processes preserved much of the extratropical cyclone's intensity,〔 allowing it to maintained hurricane-force winds until August 30. Speeding generally northeastward, the storm slowly weakened over the northern Atlantic, making landfall on Iceland on September 1. It merged with another storm system north of the country by the next day.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hurricane Cristobal (2014)」の詳細全文を読む スポンサード リンク
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