Did Delhi experience an improbable Kalbaisakhi on Sunday? The cause of the unseasonable storm

This explanation does an excellent job of connecting the unusual mid-May thunderstorms in Delhi-NCR to a broader pattern of climate variability and shifting weather dynamics. Let’s synthesise and sharpen the key points, offering a clearer view of what’s happening and why it matters:

Unseasonal Storms in Delhi-NCR: A Climate Warning

Delhi-NCR has been experiencing intense rainfall, strong gusty winds, and thunderstorms, typically not expected in mid-May. While the showers offer a brief respite from the scorching heat, their timing and intensity raise red flags about changing climate patterns and evolving weather systems.

 Could This Be a Kalbaisakhi in the Northwest?

What makes this even more unusual is the possibility that the recent storms resemble “Kalbaisakhi” or Nor’westers—fierce pre-monsoon thunderstorms traditionally confined to Eastern India (like West Bengal, Odisha, Assam, and Bihar).

Now, such phenomena seem to be migrating westwards, striking Delhi-NCR and surrounding areas—a striking example of how climate change is blurring regional meteorological boundaries.

Key Characteristics of a Nor’wester-Type Storm

• Strong straight-line winds (up to 100 km/h), sometimes comparable to derechos

• Sudden, heavy rainfall causing flash floods

• Hail or rare tornadoes in intense cases

• Radar signature often shows a bow echo—a classic sign of an organised, damaging storm system

Delhi’s late-night storm on Saturday-Sunday (around 2 a.m.) bore several of these hallmarks.

Why Did It Rain So Heavily in Delhi-NCR?

Meteorologically, four key factors converged:

1. Western Disturbance:
   A Mediterranean-origin low-pressure system collided with local heat and moisture, triggering large-scale instability.

2. Cyclonic Circulation:
   An upper-air system over Haryana and Punjab, powered by moisture from both the Arabian Sea and Bay of Bengal, enhanced convective potential.

3. Convective Heating:
   High temperatures in the plains led to intense upward motion of moist air, forming powerful thunderclouds. This energy helped drive the system southeast, towards Delhi.

4. Monsoon Trough Influence:
   Though it's still pre-monsoon, the monsoon trough has started shifting, drawing in moisture and aiding thunderstorm formation earlier than usual.

Together, these created a perfect pre-monsoon storm setup, combining large-scale systems with localized energy.

A Bigger Climate Signal?

What’s striking here is the geographical and seasonal displacement of known weather patterns:

• Kalbaisakhi-like storms are no longer restricted to Eastern India.

• May is becoming more volatile and storm-prone, not just hot.

• The intensity of wind and rainfall seems to be increasing.

These are textbook examples of what climate scientists predict—as global temperatures rise:

• Atmospheric moisture increases

• Extreme weather becomes more frequent and unpredictable

• Regional patterns shift, sometimes dramatically