Week-Long Pre-Monsoon Weather Activity Over Kerala

Pre-monsoon weather activity has generally been subpar over the northern, western, eastern and central parts of the country so far. Rainfall deficiency is to the tune of 50% for Northwest India and East & Northeast India. The shortfall is about 18% over the central parts, outside the Konkan & Goa region. However, South Peninsula has recorded an excess of 92% rainfall between 01st March and 10th April. Most subdivisions of South India, except Coastal Andhra Pradesh, have registered ‘large excess’ rainfall. The state of Kerala has a surplus of 96% rainfall during this period. In quantitative terms, the subdivision has recorded 44.3 mm of rainfall against the normal of 23.1mm during this period. Moderate to intense showers are likely for the state over the next one week, increasing the rainfall margins and likely going beyond 100%.

The main feature triggering pre-monsoon activity over the state is the Peninsular India trough. It is a semi-permanent feature, running through and through the central parts of the peninsula during April and May. This trough oscillates left and right, shifting the weather belt along with it. The heat factor in the afternoon is the additional catalyst, increasing the spread and intensity of weather. Most of the activity takes place in the late afternoon, evening and early night hours during this season.

There is a cyclonic circulation in the lower levels over the Telangana and adjoining Maharashtra region. A north-south trough is extending from this circulation and running across North Interior Karnataka, Rayalaseema, South Interior Karnataka and border areas between Tamil Nadu and Kerala. This will be the primary source of weather activity for the state over the next one week. There are two more features aiding the weather activity. A cyclonic circulation is marked over the Southeast Arabian Sea and Lakshadweep region in the lower levels. And yet another trough along and off the Tamil Nadu Coast in the Southwest Bay of Bengal, streaming moist southerly winds. These features are going to act in tandem to keep the pre-monsoon activity live over the South Peninsula for the next one week.  In this, the state of Kerala will have a bigger share. Fairly widespread rain and thundershowers are likely across the region, with chances of heavy thunderstorms and lightning at a few places. Late nights, early mornings and the forenoon period will remain relatively free of any significant weather activity. Caution needs to be exercised in the late afternoon , evening and early night.