Bhubaneswar: Odisha could be staring at another major spell of rain around September 21–22, with the latest model forecast indicating a developing weather system over the Bay of Bengal that may intensify into a depression or even a deep depression before moving across the Odisha-Andhra coast and into inland Odisha.

The forecast maps indicate that the system could bring 4–16 cm of rainfall across broad belts, with concentrated pockets potentially reaching 16–32 cm, particularly over south and west Odisha. The projected track and rainfall footprint suggest that the main weather threat could shift from coastal Odisha towards the state's southern and western districts before the system moves into Chhattisgarh.

IMD Extended Outlook has also predicted about a cyclonic circulation developing over Andaman seaa, and the system tracking northwest may reach close to Odisha – Andhra Pradesh coast around September 22/23.

September 20–22: System Builds Over Bay, Moves Inland

The NCMRWF – GLB forecast shows a heavy precipitation core developing over the Bay of Bengal on September 20, consolidating near the Odisha-Andhra coast on September 21 and moving deeper into Odisha by September 22.

The forecast therefore points to September 22 as the key period for the system's inland impact, although the rain-bearing circulation could begin affecting Odisha earlier.

The rainfall maps show a broad 4–8 cm zone, a stronger 16 cm band and isolated 16–32 cm pockets.

Forecast Rainfall Footprint

Rainfall band	Areas indicated by the model	Potential concern
16–32 cm	Ganjam, Gajapati, Rayagada and parts of Kandhamal

Extremely heavy rain pockets; flash-flood threat

Around 16 cm

Kalahandi, Koraput, Nabarangpur, Nuapada, Balangir, Subarnapur, Bargarh

Very heavy rainfall and rapid runoff

4–8 cm

Sambalpur, Jharsuguda, Sundargarh, Boudh, Angul and adjoining Chhattisgarh belt

Moderate-to-heavy rain and catchment response

2–4 cm

Bhubaneswar and Cuttack

Moderate-to-heavy showers; local waterlogging possible

The strongest rainfall signal is therefore not centred on the Twin Cities. Bhubaneswar and Cuttack appear to remain on the outer northeastern side of the system, with the core tracking farther south before turning westward.

South Odisha Could Take the First Major Hit

The forecast places Ganjam, Gajapati and Rayagada close to the strongest rainfall corridor, with parts of Kandhamal also falling within the high-rainfall zone.

The concern is not merely the rainfall total. Several of these districts contain steep terrain and river catchments where intense rain can rapidly translate into surface runoff, flash flooding and sharp rises in river levels.

The model's projected 16–32 cm rainfall pockets therefore warrant close monitoring rather than being treated as a routine monsoon spell.

Vamsadhara Basin: A Critical Watch Zone

One of the most important hydrological signals emerges from the Vamsadhara basin.

The river originates in the Thuamul Rampur hills of Kalahandi and passes through Rayagada and Gajapati before entering Andhra Pradesh. The forecast rainfall bands overlap significant portions of its upper and middle catchments.

The available CWC chart indicates that the Kashinagar gauge had already approached the basin's warning threshold during the earlier September 12–14 system.

Vamsadhara, Kashinagar	Level
Warning level	54.10 m
Danger level	54.60 m
Previous forecast peak	~54.40 m

The new September 21–22 rainfall forecast therefore raises the possibility of another rapid rise if heavy rain materialises over the catchment.

The key issue will be how much rain actually falls over the upper basin and how quickly it comes down the river, rather than the headline rainfall number alone.

Hirakud Faces a Second Inflow Test

The other major concern is the Mahanadi-Hirakud system.

The earlier September rainfall spell is projected to produce a substantial inflow surge into Hirakud, with the CWC modelling indicating a peak of around 6,200 m³/sec around September 14, followed by another high wave.

That becomes important because the next system is forecast only days later.

The September 21–22 depression could send another significant runoff pulse from western Odisha and the upper Mahanadi catchments, including adjoining Chhattisgarh, into the reservoir system.

This creates a potential back-to-back inflow scenario, leaving dam managers with a narrower window to manage reservoir storage and downstream releases.

Any major gate-release decision, however, will depend on actual reservoir levels, inflows, downstream channel conditions and official dam-management assessments closer to the event.

Bhubaneswar-Cuttack: Rain Risk, But Not the Core Impact Zone

For the Twin Cities, the forecast signal is comparatively moderate.

The maps indicate roughly 1–4 cm of accumulated rainfall on September 21 and 22, with the working estimate closer to 2–4 cm a day.

That does not suggest the Twin Cities will receive the extreme rainfall projected for southern and western Odisha.

But intense rainfall concentrated over a few hours could still create localised waterlogging, particularly in low-lying areas and places where drainage capacity is limited.

Cuttack has an additional downstream concern because of its location within the Mahanadi delta. Any substantial upstream runoff and subsequent reservoir releases could influence downstream river conditions later, depending on the actual evolution of the event.

The Big Weather Signal: September 21–22 Window

The forecast currently paints a clear sequence:

Bay of Bengal system develops → Odisha-Andhra coast comes under influence → South Odisha receives the strongest rain → system moves westward → Western Odisha and Chhattisgarh catchments receive heavy rainfall → downstream river and reservoir response follows.

That sequence makes the September 21–22 window critical for Odisha.

The immediate weather threat is expected to be concentrated over South and West Odisha, while the wider concern is the cumulative hydrological response across the Vamsadhara and Mahanadi basins.

Bottomline

The latest model guidance points to September 21–22 as a potentially high-impact weather window for Odisha, with the developing Bay of Bengal system expected to move towards the Odisha-Andhra coast and then inland.

The September 22 period currently emerges as the key day for the depression's inland impact, while South and West Odisha appear to face the strongest rainfall threat.

For the Twin Cities, the forecast is considerably less extreme, but localised waterlogging cannot be ruled out. The bigger statewide concern is the possibility that another heavy-rain spell arrives before rivers and reservoirs have fully absorbed the impact of the preceding system.