The Andhra Pradesh coast can heave a sigh of relief as the erstwhile very severe cyclone Lehar has weakened many times below cyclone status.

The erstwhile storm is now just a deep depression, the class below cyclone, even as it looks to weaken before crossing Machilipatnam this afternoon.

The precipitous fall from being a monster storm to a comparatively innocuous-looking deep depression was matched only by its frenetic intensification in the early stages.

An increasingly hostile immediate environment literally poured cold water on prospects of a further intensification after Lehar reached peak windspeeds of 140 to 150 km/hr a day ago.

Cooler waters near the coast effectively choked the supply of moisture, which essentially fuels the storm.

Moisture can be generated only from very warm waters of above 28 deg Celsius and the process of convection (cloud-building) that they promote. Additionally, it had to contend with increasing vertical wind shear.

The latter refers to the sudden change in wind strength and direction with height. Higher values of vertical wind shear lop the top off the storm tower that rises 10 to 12 km into the atmosphere.

The Met Department located the deep depression (remnant of Lehar) over west-central Bay of Bengal near latitude about 80 km east-southeast of Machillipatnam. It would move west-northwestwards, weaken further and cross the Andhra Pradesh coast near Machillipatnam.