Understanding Nor Westers: Thunderstorms in Eastern India

The question asks about the regions where Nor Westers are frequently observed. Nor Westers are a significant weather phenomenon, particularly in the eastern parts of India and Bangladesh. Understanding their characteristics and the areas they affect is key to answering this question.

What are Nor Westers?

Nor Westers are violent local thunderstorms that occur during the hot weather season, typically from March to May (the pre-monsoon season). They are characterized by:

• Sudden onset, often in the late afternoon or evening.
• Strong, squally winds, sometimes reaching very high speeds.
• Heavy rainfall, often intense but short-lived.
• Occasional hailstorms, which can be destructive, especially to crops.
• A significant drop in temperature after the storm passes.

In West Bengal, these storms are locally known as 'Kalbaisakhi' (কালবৈশাখী), meaning 'calamity of the month of Baisakh' (April-May), highlighting their destructive potential.

Regions Affected by Nor Westers

Nor Westers primarily affect the eastern states of India and Bangladesh. The most impacted regions include:

• West Bengal
• Assam
• Odisha
• Parts of Bihar and Jharkhand
• Bangladesh

These storms originate over the Chota Nagpur Plateau region or the hills of the Eastern Ghats and move eastwards or northeastwards, affecting the plains of West Bengal and Assam.

Analyzing the Options

Let's look at the given options in the context of the regions affected by Nor Westers:

Based on the geographical distribution and characteristics of Nor Westers, they are most prevalent and dreaded in the states of Bengal and Assam.

Revision Table: Key Facts about Nor Westers

Additional Information on Pre-Monsoon Storms

Nor Westers are part of the broader category of pre-monsoon thunderstorms that occur across India. These storms develop due to intense local heating and convergence of winds, leading to instability in the atmosphere.

• While Nor Westers specifically refer to storms in Eastern India, similar phenomena occur in other parts of the country, often under different local names.
• For example, in Karnataka, pre-monsoon showers are sometimes called 'Mango showers' (Amra Varsha) as they are considered beneficial for mango cultivation.
• In Kerala, similar showers are known as 'Cherry Blossom showers' or 'Coffee showers', important for coffee plantations.
• These storms bring much-needed relief from the intense heat but can also cause significant damage due to strong winds and hail.