Monsoon's Kerala date postponed, weak onset predicted by IMD
What's the story
The India Meteorological Department's (IMD) latest weather model forecasts a delayed monsoon onset over Kerala. The Global Forecast System (GFS), a sophisticated computer model, indicates that strong upper-level winds necessary for a vigorous southwest monsoon may not establish until after June 5-6. This delay could result in a mild or weak start to the monsoon season in Kerala, with rainfall intensifying gradually.
Weather dynamics
Reasons for delayed monsoon onset
The GFS model shows that a Western Disturbance, a weather system from the west, needs to clear out before essential upper-level easterly winds can strengthen over southern India. Until then, the initial monsoon flow over Kerala is likely to remain subdued. Pre-monsoon showers have already brought some rain to parts of the state, but full-fledged conditions for declaring monsoon are still developing.
Onset criteria
Conditions for declaring monsoon onset
The IMD has three conditions for declaring the monsoon onset over Kerala: sustained rainfall over 60% of designated weather stations, westerly winds of a certain speed over the Arabian Sea, and sufficient cloud cover. Currently, rain and cloud cover are adequate, but westerly winds are weak due to cyclonic activity in the Bay of Bengal. Experts expect these winds to strengthen from Monday (June 1).
Forecast revision
IMD revises rainfall forecast
The IMD has also revised its monsoon rainfall forecast for this year, now predicting below-normal rainfall due to emerging El Niño conditions in the Pacific. The initial forecast was 92% of the long-period average (LPA) for the season, but it has been downgraded to 90% of LPA. This revision raises concerns over how much impact the emerging El Niño will have on such a critical season.