Possibility of first cyclone of the year in the north Indian Ocean in the third week of May

By: Vagarian Vineet Kumar Singh (Researcher IITM )

For the first time after 2018, a cyclone likely to form in the Arabian Sea in May (figure 1a). As per various global model forecasts, chances of genesis of cyclone is possible between 16-18 May 2021 in the south central Arabian Sea.

Currently an active Madden Julian Oscillation (MJO) wave is passing through the north Indian Ocean (phase 2 as on 6 May) with amplitude 2 indicating very active MJO in the Arabian Sea. As per the model forecast (figure 1b) the active MJO conditions likely to prevail in the north Indian Ocean for another 3-4 days however it is likely to weaken thereafter (models have low confidence in predicting its strength after next 3-4 days). Further on the trailing edge of the MJO enhanced convection a rossby wave response to the MJO is forecasted in the Arabian Sea which will further amplify the relative vorticity in the region close to the equator. So MJO and Rossby wave coupled together likely to provide conducive conditions for the cyclone formation in the Arabian Sea between 16-18 May 2021. Further, warm ocean surface and subsurface conditions (as seen from SST anomalies and tropical cyclone heat potential, figure 2) likely to aid the intensification of the cyclone.