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IMD Issues Orange, Yellow Alerts After Nor’wester Storm Damage in Odisha
Severe Nor’wester (Kalbaisakhi) storms caused damage in Odisha, highlighting their role as intense pre-monsoon convective systems in eastern India.
Nor’wester (Kalbaisakhi) :
| Aspect | Key Details |
|---|---|
| Type | Convective pre-monsoon thunderstorm system. |
| Local Name | Kalbaisakhi. |
| Occurrence | March to May (pre-monsoon season). |
| Region | Eastern India (West Bengal, Assam, Odisha) and Bangladesh. |
| Wind Pattern | Blows from northwest to southeast. |
| Thermal Instability | Intense heating over Chota Nagpur Plateau creates unstable air masses. |
| Moisture Source | Warm, moist air from the Bay of Bengal. |
| Air Interaction | Cold dry winds from northwest meet warm moist air, creating instability. |
| Cloud Formation | Strong vertical wind shear leads to towering cumulonimbus clouds (18–20 km). |
| Trigger Mechanism | Local factors like sea breeze convergence trigger sudden convection. |
| Wind Speed | Typically 50–100 km/h. |
| Positive Effects | Relief from heatwaves, rainfall for crops, soil moisture retention. |
| Negative Effects | Damage to infrastructure, crop loss, uprooting of trees, lightning fatalities. |
| IMD Warning System | Green: No warning | Yellow: Be aware | Orange: Be prepared | Red: Take action. |
| Climatic Significance | Indicates transition from pre-monsoon to monsoon conditions. |