Context
The 2026 southwest monsoon recorded 77 Low Pressure System (LPS) days, exceeding the long-period normal of around 57 days. However, rainfall remained uneven across India, highlighting the role of LPS movement and intensity in regional rainfall distribution.
About Low Pressure Systems (LPS)
- Meaning: A region where atmospheric pressure is lower than its surroundings, drawing in air and promoting cloud formation and rainfall when moist air rises and condenses.
- Role in Monsoon: These rain-bearing disturbances heavily influence rainfall distribution during the June–September southwest monsoon. Many develop over the Bay of Bengal and track inland across the monsoon trough.
- Monsoon Branches: The southwest monsoon reaches India through two primary pathways: the Arabian Sea branch and the Bay of Bengal branch.
- LPS Days: The total number of days on which at least one LPS is active over the defined Indian region, serving as a metric for the persistence of monsoon activity rather than the sheer count of systems.
Key Features of the 2026 Monsoon
- LPS Activity: India recorded 14 LPS events and 77 LPS days, exceeding the long-period average (normal of 13 events and 57 days). 6 systems intensified into depressions, of which 3 became deep depressions.
- Uneven Spatial Rainfall:
- July: Odisha recorded 34% excess rainfall, whereas Bihar faced a 42% deficit.
- August: The Southern Peninsula recorded a 27% rainfall deficit.
- September: Northwest India received 17% excess rainfall, while East and Northeast India recorded a 25% deficit.
- Regional Impact: LPS concentrate heavy precipitation strictly along their tracks, leaving non-path regions with skewed spatial distribution and dry spells.
Significance and Implications
- Agriculture: Uneven rainfall causes waterlogging and crop damage in some regions, while increasing irrigation stress in others.
- Disaster Risk: Intense rainfall can trigger flash floods, river floods and landslides, particularly in the Himalayan region.
- Water Resources: Rainfall variability affects reservoir inflows, groundwater recharge and water availability for drinking and irrigation.
- Economic Impact: Flood-related damage to infrastructure, crops and transport disrupts livelihoods and increases recovery costs.
Challenges
- Forecasting Uncertainty: Predicting the location, duration and intensity of rainfall events remains difficult.
- Regional Variability: Excess rainfall at the national level can mask deficits in specific regions, complicating local water management.
- Multiple Climatic Factors: LPS interact with El Niño–Southern Oscillation (ENSO), the Madden–Julian Oscillation (MJO) and jet streams, making rainfall patterns complex.
- Limited Long-Term Evidence: Short-term data are insufficient to establish sustained trends in LPS frequency, persistence and intensity.
Way Forward
- Improve Forecasting: Strengthen weather observation networks, satellite monitoring and numerical weather prediction to track LPS activity.
- Impact-Based Warnings: Issue localised alerts for extreme rainfall, floods and landslides to support timely evacuation and response.
- Climate-Resilient Agriculture: Promote weather-based advisories, suitable cropping patterns, better drainage and efficient irrigation.
- Water Management: Improve reservoir operations, rainwater harvesting and groundwater recharge based on regional rainfall patterns.
- Long-Term Assessment: Use multi-decadal data to identify sustained changes in LPS activity and distinguish them from natural variability.
FAQs
Q1. What is a Low Pressure System (LPS)?
Ans. An LPS is a weather disturbance associated with low atmospheric pressure that can cause rainfall.
Q2. Why are LPS important for India’s southwest monsoon?
Ans. They bring moisture inland and influence rainfall, particularly across central and northern India.
Q3. Does an increase in LPS days guarantee higher rainfall?
Ans. No, rainfall depends on the systems’ intensity, duration, movement and prevailing atmospheric conditions.
Q4. How do LPS affect agriculture and water resources?
Ans. They can cause crop damage and flooding, while uneven rainfall affects irrigation, reservoir inflows and groundwater recharge.
