The India Meteorological Department (IMD) has issued a depression formation alert over the east-central Arabian Sea off north Karnataka-Goa. A preparatory cyclonic circulation, marked by intense convection and cloud building early on Wednesday morning, formed over the area ahead of the expected onset of the monsoon.
The circulation (Invest 93A) will descend to lower levels to become a low-pressure area, pushing north and intensifying into a depression. Low wind shear and optimum sea-surface temperatures will aid this development.
Wind shear is change in speed and direction with height in this context. Higher wind shear will not allow storm tower to build to required specifications. Warm seas help with accelerated evaporation, convection and cloud formation. Shear values can go up once monsoon establishes to full scale, which is why cyclones do not usually form during the midst of the season.
