12A.4 Causes for collapse of transitioning mesoscale convective systems in the East Atlantic

Wednesday, 28 September 2011: 11:15 AM
Monongahela Room (William Penn Hotel)
Amber E. Reynolds, NASA/GSFC, Greenbelt, MD; and G. M. Heymsfield, G. S. Jenkins, and C. C. Weiss

While most MCSs dissipate upon approaching the coast of West Africa and transitioning to the East Atlantic, a few cases have been shown to strengthen, such as Hurricane Cindy (1999). A better understanding of how some MCSs decay is essential for identifying other MCSs that go on to play a role in tropical cyclogenesis. A six-year (2000-2006) climatology of TRMM PR data were used to construct CFADs of three regimes (continental, transition, and oceanic) in the region of West Africa and the Eastern Atlantic. After establishing the differences between MCSs in these three regimes, datasets from the NASA African Monsoon Multidisciplinary Analyses (2006) field campaign were used to investigate the environments of transitioning MCSs as well as small-scale factors contributing to localized convection. Our results show that MCSs that initiate over the continent of West Africa and transition unsuccessfully into the East Atlantic are fundamentally different from subsequent convection associated with tropical cyclogenesis downstream due to changes in updraft structure supporting additional convection. These results should prove useful for incorporation into tropical cyclone models with domains including regions east of the Cape Verde Islands.
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