Mini-cloudbursts

Why in the News? 

According to the India Meteorological Department (IMD), even as an increase in cloudbursts in India has not been observed; the number of mini-cloudbursts has been on the increase over the past few years. This was noted by IMD Director-General Mrutyunjay Mohapatra, when he gave a press conference (Aug 2025).

Key Points: Mini-cloudbursts

• Cloudbursts: Extremely heavy rainfall (≥100 mm in an hour) over a small area, often in hilly terrain.
• The reason why cloudbursts are unpredictable: Cloudbursts according to IMD can never be forecasted using the current technology as they are constrained and local.

Mini-cloudbursts:

• Increasing in number in recent years.
• Defined as very heavy localized rainfall (but less intense than a cloudburst).
• More frequent in urban areas and plains due to climate variability and urbanization.

Monsoon 2025 Update:

• Rainfall in September is likely to be above the usual level, projected to be around 9% higher than the long-term average of 16.7 cm.
• June–August rainfall was 6% above normal.
• Northwest India (Uttarakhand, UP, Punjab, Haryana, Delhi, J&K, Rajasthan) saw 26% surplus rainfall.
• Eastern & Northeastern India had a 17% rainfall deficit.

August 2025:

• Northern India rainfall: highest since 2001 (26.5 cm).
• Southern Peninsula rainfall: 3rd highest since 2001 (25 cm).
• >700 instances of heavy rain (20 cm/day) recorded – 2nd highest after 2024.

What is a Cloudburst?

A cloudburst is a sudden, intense rainfall event over a small area, leading to flash floods.

• Definition (IMD): Rainfall of ≥100 mm (10 cm) in one hour over a localized area (often less than 20–30 sq. km).
• Nature: Extremely localized → cannot be predicted precisely.
• Typical Region: Mostly occurs in hilly and mountainous regions (Himalayas, Western Ghats), but can also occur in urban areas.

Characteristics of Cloudbursts:

• Sudden onset – happens within minutes.
• High intensity – very heavy downpour in a short span of time.
• Localized impact – confined to small geographical areas.
• The effects can range from flash floods and landslides to destruction of infrastructure and loss of lives.

Causes of Cloudbursts:

• Orographic lifting: When moist air is forced upward by mountains, it cools quickly and condenses.
• Convective activity: Strong vertical clouds (cumulonimbus) with high moisture.
• Blocked winds: When monsoon currents collide with mountains, they slow down and release intense rainfall in a short span.

Examples:

• Kedarnath (2013, Uttarakhand) – catastrophic flooding.
• Leh (2010, Ladakh) – flash floods due to cloudburst killed hundreds.
• Himachal Pradesh, J&K, Uttarakhand – frequent recent cases.