IMD monsoon forecast: Kerala set for weak monsoon onset as El Nino threat grows

PTC Web Desk: The southwest monsoon is expected to make a soft entry over Kerala this week as crucial atmospheric conditions required for a strong onset are yet to fully develop, according to the latest weather model projections from the India Meteorological Department (IMD).

Recent runs of the IMD’s Global Forecast System (GFS) model indicate that the upper-level easterly winds, considered vital for strengthening monsoon circulation over South India, are likely to become fully active only after June 5 or 6. As a result, the monsoon’s arrival over Kerala may begin on a weaker note before gradually gaining momentum in the following days.

The southwest monsoon plays a critical role in India’s economy and agriculture, delivering nearly 70% of the country’s annual rainfall between June and September. The seasonal winds help replenish reservoirs, support kharif crop sowing, and offer relief from scorching summer temperatures.

Meteorologists say the delay in strengthening monsoon winds is partly linked to the presence of a Western Disturbance,  a weather system originating from the Mediterranean region that carries moisture and affects atmospheric circulation over northern India. Until this system clears, the strong easterly winds needed to energise the monsoon flow over southern India are expected to remain weak.

The monsoon has already shown signs of advancement with pre-monsoon showers lashing several parts of Kerala. However, the IMD has not yet officially declared the onset as all required parameters are still not being met simultaneously.

For the IMD to confirm the onset of the monsoon over Kerala, three key conditions must be satisfied at the same time. These include rainfall occurring at 60% of designated weather stations in Kerala for two consecutive days, adequate westerly wind speeds over the Arabian Sea and sufficient cloud cover in the region.

At present, rainfall activity and cloud formation are considered favourable, but the westerly winds remain below the required strength. Weather experts believe cyclonic activity in the Bay of Bengal earlier weakened the monsoon flow, slowing its progress toward the Kerala coast.

Despite the delay, meteorologists expect wind patterns to improve gradually during the first week of June, increasing the likelihood of the monsoon officially arriving over Kerala within the next few days.

The IMD had earlier projected the monsoon onset around May 26, but changing atmospheric conditions forced repeated revisions in the forecast. The latest estimate places the onset window between June 2 and June 4.

While the monsoon’s arrival appears imminent, concerns remain over the overall performance of the rainy season. The IMD has already predicted below-normal rainfall for the country this year due to emerging El Nino conditions in the Pacific Ocean, which typically weaken Indian monsoon rainfall.

The department initially estimated seasonal rainfall at 92% of the Long Period Average (LPA), but recently revised the forecast downward to 90% of the LPA. The downgrade has raised worries about the possible impact on agriculture, water supply, and power demand during the peak summer months.

The situation is especially significant as large parts of northern and central India continue to reel under intense heatwave conditions. Farmers across several states are awaiting timely monsoon showers to begin sowing operations for the kharif season.

Weather experts, however, point out that monsoon systems evolve continuously and forecasts may change as new atmospheric data becomes available. Current indications suggest that although the onset may be less vigorous than usual, rainfall activity is likely to strengthen progressively through June.