Satellite images are often used to assess the state of a tropical cyclone's environment, helping to determine the direction, magnitude and vertical extent of wind shear that is affecting the storm. Tropical cyclones that are affected by wind shear often appear elongated with there deep convection confined on the down shear side of the storm. Sometimes, however, in very weak wind shear conditions asymmetries arise for different reasons. The purpose of this work is to observationally determine the convective asymmetries that arise in association with the motion of the tropical cyclone. This is an important stepping stone toward the understanding of convective asymmetries in tropical cyclones, and will help in creating better assessments of vertical wind shear from satellite imagery alone.
Convective asymmetries of tropical cyclones, which are maintaining nearly constant intensities and have clearly defined eyes, are examined using average storm relative infrared images. Individual images that make up the averages have been centered and rotated along the motion vector. Of particular interest is the tendency for the new cold cloud tops to most often form on the forward edge of the eyewall. These colder clouds then rotate around the left edge of the eyewall forming a clear asymmetry. Other motion related asymmetries would be discussed.