EXCLUSIVE| Deep Depression Cloud Structure Revealed: Check How Your District Will See Heavy to Very Heavy Rainfall in Odisha

Bhubaneswar: The cloud structure of Deep Depression is now providing a clearer picture of how the rainfall distribution is likely to unfold across Odisha as the system turns northwestward and moves inland.

Rather than producing uniform rain across the State, the system's rain field is organised into two distinct structures – a dense southwest (SW) rain plume along the core track and outer convective feeding bands farther away from the centre.

The distinction is important: districts lying beneath the SW plume are likely to experience long-duration, continuous heavy to very heavy rain, while coastal, central and northern parts of Odisha can get short-duration but intense rainfall bursts as the outer convective bands sweep through.

The rainfall episode linked to the system is expected to remain active for roughly three days in its main phase – from the night of September 23 through September 25 – with weakening remnant rainfall extending into September 26. The peak impact comes between the night of September 23 and September 25.

The cloud structure: Two rain engines operating at once

The deep depression's rain-producing structure is divided into two operational bands.

The first is the dense, heavily sheared Southwest Plume, which is aligned more closely with the system's northwestward land track. It is capable of producing prolonged and torrential rainfall as the core moves across southern and western interior Odisha.

The second consists of Outer Convective Feeding Bands. These bands are farther from the centre and behave differently – rainfall comes in pulses, with intense downpours followed by temporary breaks.

In simple terms, the core track determines where rain stays for longer, while the outer bands determine where sudden cloudbursts can occur away from the centre.

What this means for Odisha

Rain structure	Where it acts

Rain character

Main period

SW Plume

Southern & western interior Odisha

Continuous, torrential

Sept 23 night–Sept 25

Outer Convective Bands

Coastal, central & northern districts

Intermittent intense bursts

Sept 24–25

Remnant circulation

Western/interior Odisha towards Chhattisgarh

Scattered/intermittent

Sept 25–26

Northwestward movement puts southern Odisha first in the firing line

As the deep depression turns northwestward after its coastal approach, the rainfall focus shifts progressively inland. The assessment places Ganjam and Gajapati in the near-landfall zone, followed by an inland passage through Gajapati, Rayagada and Koraput.

This makes southern Odisha the first major zone of prolonged rain before the system's rain-bearing structure shifts westward towards Nabarangpur, Kalahandi, Bolangir, Nuapada and adjoining western districts.

The system's wind field also weakens progressively as it interacts with the rugged terrain of the Eastern Ghats. The forecast timeline shows winds of 45–55 kmph gusting to 65 kmph during the post-landfall inland passage across Gajapati, Rayagada and Koraput, before weakening further as the system moves towards western Odisha.

District-wise rainfall: Where the heaviest rain is likely to persist

The most consequential rainfall is expected underneath the SW plume.

1. Koraput–Malkangiri–Nabarangpur: 200–300 mm possible

The first and most intense continuous rainfall zone includes Koraput, Malkangiri and Nabarangpur.

The assessment puts rainfall in this belt at 200–300 mm or more at isolated locations, with the continuous rain potentially lasting 24–36 hours.

Core impact window: Midnight September 23 to night of September 24.

This is the zone where accumulated rainfall, rather than merely hourly intensity, becomes the bigger concern.

2. Kalahandi–Rayagada–Kandhamal: 110–200 mm

The next major rain belt covers Kalahandi, Rayagada and Kandhamal, where rainfall is projected in the 110–200 mm very-heavy category.

The continuous rainfall window is estimated at 18–24 hours, broadly from the morning of September 24 to the afternoon of September 25.

3. Bolangir–Nuapada–Bargarh: 70–150 mm

As the system shifts farther northwest, Bolangir, Nuapada and Bargarh enter the core rainfall corridor.

These districts can receive 70–150 mm, with the heavier spell persisting for approximately 12–18 hours from the afternoon of September 24 into the night of September 25.

Core rainfall corridor

District belt	Expected rainfall	Duration of heavier spell	Main impact window
Koraput, Malkangiri, Nabarangpur	200–300+ mm isolated	24–36 hrs	Sept 23 night–Sept 24 night
Kalahandi, Rayagada, Kandhamal	110–200 mm	18–24 hrs	Sept 24 morning–Sept 25 afternoon
Bolangir, Nuapada, Bargarh	70–150 mm	12–18 hrs	Sept 24 afternoon–Sept 25 night

Coastal Odisha: Less continuous, but sharper rain bursts

The cloud structure also explains why the coastal belt cannot be treated as being outside the main rain threat.

Bhubaneswar, Cuttack, Khurda and Puri remain connected to the system through the outer convective feeding bands. Here, the rain is expected to be intermittent rather than continuous, but individual spells can become intense.

The assessment indicates the possibility of 30–50 mm per hour spikes during the peak phase, with intense one-hour bursts capable of producing temporary urban waterlogging. The intermittent heavy rain is expected to continue until around midday September 24, after which the spells become increasingly sporadic.

That means a lower cumulative rainfall total in these cities should not automatically be interpreted as a low-impact rainfall event: rainfall intensity over a short period becomes the critical factor for urban areas.

Ganjam–Gajapati: Near the system's landfall zone

Ganjam and Gajapati are identified as the near-landfall districts.

The rain bands here are expected to sweep frequently during the night of September 24, with the system shifting farther inland by the early morning of September 25. Squally coastal winds could reach up to 75 kmph during the passage of the heavier bands.

The first major rainfall phase — from around 9 PM September 23 to 2 PM September 24 — is projected to bring 110–200 mm over Ganjam, Gajapati, Rayagada and Koraput, with isolated locations in the southwestern plume potentially crossing 250 mm.

The rainfall will migrate westward — not disappear immediately

The second phase begins around the afternoon of September 24.

By then, the continuous heavy-rain core shifts westward towards Kalahandi, Nabarangpur, Bolangir and Nuapada, where the expected accumulation is 70–150 mm.

This is the crucial transition in the system: southern Odisha moves out of the peak core while western Odisha moves into the main rainfall corridor.

Rainfall movement at a glance

Time	System/rainfall phase	Main districts/areas
Sept 23 night–Sept 24 afternoon	Peak landfall impact; torrential rain	Ganjam, Gajapati, Rayagada, Koraput
Sept 24 afternoon–Sept 25 morning	Heavy core shifts inland/westward	Kalahandi, Nabarangpur, Bolangir, Nuapada
Sept 25	Remnant system; rain becomes intermittent	Western/interior Odisha
Sept 26	Weakening/remnant influence	Scattered residual rain

How long will the Deep Depression rain remain over Odisha?

The main Deep Depression rainfall episode is expected to last about three days, from the night of September 23 through September 25, while residual rainfall influence can continue into September 26.

The distinction between the two is important.

September 23 night–25: the period of greatest concern for heavy to very heavy rainfall.

September 25–26: the system weakens substantially, with rainfall becoming intermittent and scattered. General accumulations during the remnant phase are projected at 30–60 mm, although runoff can continue to keep rivers elevated for several hours.

Rivers and runoff could remain an issue after the rain weakens

The rainfall threat does not end at the moment the depression weakens.

The prolonged SW-plume rainfall over the southern and western catchments means that runoff and river response can continue even after the organised rain bands begin to weaken. The source specifically flags rapidly accelerating river levels around Kashinagar and Gunupur during the peak rainfall phase.

This creates a two-stage hydrological threat: intense rainfall first, followed by delayed runoff and river response.

The bottom line

The defining feature of Deep Depression 01B is therefore not simply the total rainfall, but the architecture of its rain field.

A concentrated SW plume will keep southern and western interior districts under prolonged rain, while outer convective bands will intermittently hammer coastal and central Odisha with sharp rainfall bursts.

The State's rainfall sequence is expected to move broadly from Ganjam–Gajapati and the southern districts → Rayagada–Koraput/Nabarangpur → Kalahandi–Bolangir–Nuapada–Bargarh, before weakening towards the Chhattisgarh side.

So, while the peak heavy-rain threat is concentrated between September 23 night and September 25, Odisha's weather and river systems may continue to feel the depression's effects into September 26 as the remnant circulation moves farther inland.
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