 Karen 's organization and intensity remained steady for the next day . Early on September 26 , however , the storm strengthened significantly . In post @-@ operational analysis the cyclone was determined to have reached hurricane @-@ strength for about twelve hours . The strengthening was short @-@ lived because a sharp upper @-@ level trough to the west of Karen increased the amount of vertical wind shear over the hurricane . By September 28 these unfavorable conditions had weakened Karen to a marginal tropical storm and left its low @-@ level circulation exposed . Meanwhile , the storm began heading northward and experiencing intermittent bursts of deep convection . However , the relentless wind shear exposed the system 's circulation until it dissipated in the mid @-@ Atlantic on September 29 . Karen 's remnants lingered near the Leeward Islands for the next few days , although the system never directly affected land . As a result , no reported damages or casualties were associated with Karen . 
