Topic > Northern Hemisphere Hurricane Rainfall

Hurricane Irene struck the Caribbean and much of the U.S. East Coast and was one of the most damaging tropical cyclones of the 2011 Atlantic tropical cyclone season. originated east of the Lesser Antilles from a well-defined Atlantic tropical wave in that area, and became Tropical Storm Irene on August 20, 2011. Irene reached its highest point as a 120 mph Category 3 hurricane. Irene was ranked as the seventh costliest hurricane with damages costing approximately $15.6 billion in the United States. Irene produced record rainfall in the mid-Atlantic and northeastern United States. The highest rainfall recorded during Hurricane Irene's storm surge occurred in Bayboro, North Carolina, with approximately 15.7 inches of rain. At least half of the deaths caused by Irene in the United States were due to freshwater flooding from heavy rain. As tropical cyclones cross the northeastern United States, they are restructured by the course of the extratropical transition. This is caused by contact with strong westerly winds that are associated with a mid-latitude trough and causes increased storm forward motion, vertical wind shear, and vorticity. An increase in the forward motion of the storm also plays a role in the speed of the wind produced by the hurricane. Where the circulating winds and the entire storm move in the same direction, the wind speed is amplified by the forward motion of the storm. In the Northern Hemisphere, the right side of a hurricane, when looking at the path it is moving, has the greatest wind speed and therefore is the most dangerous part of the storm. Strong vertical wind shear within the troposphere also reduces the development of tropical cyclones. This makes half the paper the 12 tropical cyclones examined in this study. Hurricane Floyd was the tropical cyclone in this study with the most similar trajectory to Irene. Floyd had produced the highest rainfall totals over 24% of the study region. Spatial precipitation patterns differed for all 12 tropical cyclones considered, but followed similar paths. This can be explained by looking at where the highest rainfall totals occurred along the route. Some tropical cyclones produced higher precipitation totals in the southern or western part of the study region, while others produced higher precipitation totals closer to the storm's path. Other tropical cyclones had a rain field that widened or narrowed during their storm period. Thus, there is no single pattern that can be captured by the 12 similar tropical cyclone tracks in this study.