THIRUVANANTHAPURAM: The Central Meteorological Department has predicted heavy thundershowers in the state till November 1. Orange alert has been sounded in Thiruvananthapuram, Kollam, Pathanamthitta, Alappuzha, Kottayam and Idukki districts tomorrow. Rainfall in the state is a result of low pressure formed in the central part of the Bay of Bengal. Isolated showers are also possible. The state disaster management authority asked the people to be vigilant.