Northeast monsoon strengthens; cyclone possible by November 19 in Tamil Nadu

By Tom Whitfield

Tamil Nadu and Puducherry recorded 25.4 cm of rainfall between October 1 and November 9, four per cent above the 24.3 cm seasonal normal. In its November 10 report from Chennai, the Regional Meteorological Centre (RMC) said the northeast monsoon had intensified across Tamil Nadu, with further rain forecast through the middle of November.

The surplus does not remove the immediate operational risk. The RMC forecast “widespread downpours” and warned that a low-pressure area over the Bay of Bengal “could develop into a cyclonic storm next week.” Farmers must separate the short-term rain forecast from the longer storm threat rather than treat the seasonal surplus as an all-clear.

What changes for field operations?

RMC expects moderate rain across the Delta and southern districts until November 15. Heavy showers with thunderstorms are forecast for isolated places in Ramanathapuram and Thoothukudi. The contrast matters operationally because continuous rain and isolated thunderstorms do not create the same field-access risk.

For growers, the immediate choices concern spraying, irrigation scheduling and machinery movement. A grower can use the November 15 window to protect a work programme, but isolated thunderstorms require a forecast for the exact work location. The combined 25.4 cm total cannot replace that local check.

Because the bulletin does not identify individual farms or crops, it offers a timetable rather than a prescription to apply or withhold inputs. It does, however, give growers two clear dates for reviewing their plans.

• Through November 15: Plan around moderate rain across the Delta and southern districts, with local allowances for heavy showers and thunderstorms in Ramanathapuram and Thoothukudi.
• Around November 12: Reassess the coastal threat when the RMC expects a fresh low-pressure system to form over the southeastern Bay of Bengal.
• By November 19: Do not treat the date as a confirmed landfall. The developing system could intensify and move towards the Tamil Nadu coast, with potential cyclone status by that date.

The forecast calendar creates a practical sequence. Until November 15, the main issue is whether rain and thunderstorms interrupt planned work. From November 12, farmers also need to track the developing low over the southeastern Bay of Bengal. The two windows overlap, so a short-term work plan and a storm contingency have to run together.

The low-pressure area does not yet equal a cyclone. The RMC's forecast gives a conditional path: intensification, movement towards the Tamil Nadu coastline and possible cyclone status by November 19. No confirmed landfall point or timing appears in the report, and a track towards the coast does not establish landfall.

That uncertainty argues for updating plans, not assuming the worst. Farmers can keep non-urgent work flexible through the rain window and use official local forecasts before committing labour and machinery to time-sensitive operations. If the low strengthens or warnings change, the operational response can move from routine weather delays to a more serious coastal contingency.

The current four per cent surplus also needs a restrained interpretation. It confirms that the northeast monsoon has delivered more rain than its seasonal benchmark across Tamil Nadu and Puducherry through November 9. It does not remove the possibility of further heavy falls because a fresh system is expected to form around November 12, after that measurement period.

That final point keeps the operational response proportionate. The 25.4 cm total describes rainfall through November 9; forecasts from November 10 onward describe what has not arrived. Farmers should use the near-term signal to adjust daily operations, while treating the November 19 cyclone horizon as a separate risk that can change as the low develops.

The next checkpoints are November 15, when the current moderate-rain window runs out, and November 19, the outer date for possible cyclone status. Local RMC updates will show whether field plans remain routine or shift into storm contingency.