Rapid Movement of Cyclone Viyaru Just Before Landfall-A Case Study

Abstract

A depression formed over southeast Bay of Bengal at 1430 h IST of 10 May 2013 near latitude 5.0° N and longitude 92.0° E. It moved northwestwards and intensified into a deep depression in the evening of the same day. Continuing its northwestward movement, it further intensified into a cyclonic storm, Viyaru in the morning of 11 May 2013. Under the influence of the anti-cyclonic circulation lying to the east, the cyclonic storm changed its direction of movement initially from northwestward to northward and then to north-northeastward on 13 and 14 May, respectively. On 15 May, it further came under the influence of the mid-latitude westerly trough running roughly along 77° E, which further helped in enhancing the north-northeastward movement of the cyclonic storm. As this trough came closer on 16th, the north-northeastward speed of the cyclonic storm significantly increased, becoming about 40–50 kmph. The cyclonic storm crossed Bangladesh coast near latitude 22.8° N and longitude 91.4° E, about 30 km south of Feni around 1330 h IST of 16 May 2013 with a sustained maximum surface wind speed of about 85–95 kmph. Maximum surface wind of 92 kmph has been reported over Patuakhali, Bangladesh during the time of landfall. Widespread rainfall with isolated heavy to very heavy falls occurred over Bangladesh. Fairly, widespread rainfall with isolated heavy rainfall also occurred over Mizoram, Manipur and Tripura. A storm surge of height of about 1 m has been reported in section of media. After the landfall, it continued to move north-northeastwards and weakened gradually due to interaction with land surface. It weakened into a deep depression over Mizoram in the evening and into a depression over Manipur around mid-night of 16th. It further weakened into a well-marked low pressure area over Nagaland in the early morning and moved away towards Myanmar as a low pressure area in the morning of 17th.