Thiruvananthapuram: The India Meteorological Department (IMD) on Tuesday revised its weather forecast, extending the orange alert for Ernakulam, Idukki, Thrissur, Palakkad and Malappuram. A yellow alert has been issued for Thiruvananthapuram, Kollam, Pathanamthitta, Alappuzha, Kottayam, Wayanad, Kannur and Kasaragod.

For Wednesday, a red alert has been sounded for Pathanamthitta, Alappuzha, Kottayam, Ernakulam and Idukki, while an orange alert has been issued for Kozhikode, Wayanad, Pathanamthitta, Alappuzha, Kottayam, Ernakulam and Thrissur. A yellow alert is in place for Kannur, Kasaragod, Thiruvananthapuram and Kollam.

According to the weather agency, a well-marked low-pressure area over the southeast Arabian Sea is likely to intensify into a depression while moving westwards during the next 24 hours. Another low-pressure area is also likely to form over the southeast Bay of Bengal within the same period. It is expected to move west-northwestwards and intensify further into a depression over the central parts of the south Bay of Bengal and adjoining west-central Bay of Bengal over the subsequent 48 hours.

The upper air cyclonic circulation over south Kerala and adjoining Comorin area now lies over the southeast Arabian Sea off the Kerala coast and extends up to 1.5 km above mean sea level. A trough runs from this cyclonic circulation to the south Andaman Sea, across the southeast Arabian Sea, at about 0.9 km above mean sea level.

Under the influence of these systems, widespread rainfall activity with heavy (7–11 cm in 24 hours) to very heavy rainfall (12–20 cm in 24 hours) is very likely at one or two places in Kerala between October 22 and 24. Heavy rainfall is also likely at isolated places on October 21, 25, and 26, and over Lakshadweep between October 20 and 22.

Districts under red alert: 
October 22: Idukki, Palakkad and Malappuram

Districts under orange alert:
October 21: Ernakulam, Idukki, Thrissur, Palakkad and Malappuram
October 22: Pathanamthitta, Alappuzha, Kottayam, Ernakulam, Thrissur, Kozhikode and Wayanad
October 23: Kozhikode, Wayanad

Districts under yellow alert:
October 21: Thiruvananthapuram, Kollam, Pathanamthitta, Alappuzha, Kottayam, Wayanad, Kannur and Kozhikode  
October 22: Thiruvananthapuram, Kollam, Kannur and Kasaragod
October 23: Thiruvananthapuram, Kollam, Pathanamthitta, Kottayam, Malappuram, Kozhikode and Wayanad

Probable impacts due to heavy rain
The IMD has warned of several possible impacts due to the heavy to very heavy rainfall expected in the coming days. Poor visibility and traffic congestion are likely during intense spells of rain, along with waterlogging, uprooting of trees, and damage to power lines. Kutcha houses and other vulnerable structures may also suffer damage, while flash floods, landslides, and flooding in low-lying areas are possible. Surface and helicopter transport could be disrupted, and heavy rainfall may harm standing crops and vegetables, causing soil erosion. There is also a risk of lightning injuries to people and cattle in open areas.

Authorities have advised the public to follow traffic advisories and avoid waterlogged or landslide-prone regions. People are urged to stay away from vulnerable structures and riverfronts. Farmers have been asked to provide mulch at the base of crops and avoid working in the fields during thunderstorms. Tourism and recreational activities are expected to be regulated, and sowing of seeds should be postponed to prevent water stagnation. The IMD has also urged residents to stay updated with official weather alerts.