THIRUVANANTHAPURAM: Isolated showers are likely till Friday in the southern districts of the state. The central and northern districts will receive normal rainfall with thunderstorms. The rain is due to the cyclone formed in the Bay of Bengal. This will likely turn into a low pressure on Tuesday. It will strengthen again into extreme low pressure and move towards the coast of Tamil Nadu. Yellow alert has been issued for Chennai and other districts in northern Tamil Nadu. Yellow alert has been issued for Thiruvananthapuram, Kollam, Pathanamthitta, Kottayam, Idukki, Ernakulam, Thrissur, Palakkad, Malappuram, Kozhikode and Wayanad.