The influence of upper level surrounding winds on tropical cyclone motion: a case study of the Bay of Bengal region

The study is an attempt to classify the observed tropical cyclone (TC) track patterns over the Bay of Bengal (BoB) region. It is hypothesized that winds at 200 hPa level can determine the direction of TC motion. We found that the mean TC genesis locations were shifted southward from October to December with the shifting of the regional wind circulation patterns. The wind circulation pattern during the straight moving TCs were very similar to the recurving TCs. Straight moving TCs were embedded in a deep easterly flow whereas the recurving TCs significantly moved further northward compared to the straight tracks which brought them under the influence of mid-latitude westerlies and changed their paths towards northeast. A TC track prediction scheme is presented to evaluate the effectiveness of 200 hPa level surrounding winds in TC motion prediction. Sea level pressure fall and relative vorticity advection also have been used as supportive factors. We found results comparable with other TC track prediction models which did not consider the upper level surrounding winds as a TC track predictor. Hence, the use of 200 hPa level winds might be beneficial to improve the existing TC track prediction models over the BoB region.