EXCLUSIVE| Cyclone Arnab Fails to Cool Hotter Bay of Bengal, Another Cyclonegenesis By Nov 1 in Southeast Bay; What it means for Odisha?

Bhubaneswar:  Even as Coastal Andhra Pradesh and Odisha brace for the immediate heavy rainfall and localized flash flooding from Cyclone Arnab, an extraordinary and deeply concerning oceanic phenomenon is unfolding across the Bay of Bengal.

Fresh meteorological modeling data and satellite oceanic tracking indicate that Cyclone Arnab - forecast to bring severe downpours to the Godavari delta and sprawling convective rainbands across the twin cities of Bhubaneswar and Cuttack - is failing to perform one of the primary ecological duties of a tropical system: cooling down the ocean surface.

Standard atmospheric science dictates that as a Very Severe Cyclonic Storm (VSCS) charts its path over open waters, its violent internal wind fields induce powerful mechanical churning, upwelling cold water from the ocean depths to leave behind a chilled trail.

Yet, real-time data from the Indian National Centre for Ocean Information Services (INCOIS) tells an entirely different, alarming story. The sea surface temperatures (SST) in the wake of the active storm continue to hover at blistering levels between 29.5°C and 31.0°C. This baseline is nearly four degrees above the critical 26.5°C threshold required to ignite tropical cyclogenesis.

With the ocean acting as an unyielding thermal powerhouse, the India Meteorological Department (IMD) has officially sounded an extended outlook alert.

Before the rain from Cyclone Arnab can completely dry off the streets of coastal towns, a secondary, potent low-pressure system is forecast to take structural shape in the Southeast Bay of Bengal, solidifying into a distinct tropical depression by November 1, 2026.

Why Arnab Failed to Chill the Basin

The structural physics behind why Cyclone Arnab is leaving the Bay of Bengal super-heated lies in the concept of Ocean Heat Content (OHC). Over the preceding months of 2026, solar radiation and stagnant atmospheric conditions packed immense thermal energy deep into the ocean's subsurface layers.

When a cyclone moves over a basin with a shallow layer of warm water, its winds easily reach the cold thermocline below, bringing up cold water that chokes off the storm's fuel supply. However, thanks to super El Nino, the current state of the Bay of Bengal features an unusually deep marine heat wave layer.

Cyclone Arnab is churning the sea, but it is only mixing warm water with more warm water underneath.

Because this deep reservoir of latent heat remains completely intact, the ocean surface will remain highly volatile. This means that by November 1, when the next tropical disturbance steps onto the maritime stage, it will find an environment that is just as thermodynamically explosive as the one enjoyed by its predecessor.

A Tale of Two Tracks: The Meteorological Tug-of-War

As both global and national numerical weather prediction models confirm the fast-approaching November 1 genesis timeline, a fascinating and high-stakes divergence has broken out among major forecasting agencies regarding where this new system will travel.

An analysis of the medium-range ensemble tracking presents a complex, split atmospheric profile:

Steering & Modeling Factor	NCMRWF MITHUNA Path	ECMWF Ensemble Path
Ridge Behavior	Ridge breaks / tilts	Ridge stays flat & rigid
Track Direction	Direct North-Northwest track	Pushed West-Southwestward
Projected Landfall / Target	Targets: Odisha & West Bengal	Targets: Tamil Nadu & Sri Lanka

The National Centre for Medium Range Weather Forecasting (NCMRWF), utilizing its advanced Mithuna-GLB global modeling system, projects an aggressive, highly organized, and vertically stacked cyclonic vortex. The NCMRWF maps indicate that the environmental steering parameters will allow this new system to march directly north-northwestward up the spine of the Bay. According to this model, the system will travel over an uninterrupted highway of hot water, tracking directly toward the coastal border of Odisha and West Bengal by November 1 or 2.

Conversely, the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble remains highly ambiguous and geographically split, showing two distinct "arms" of probability. One arm curves upward toward Odisha, acknowledging the NCMRWF's solution. However, a prominent secondary arm pushes directly west-southwestward toward Tamil Nadu and Sri Lanka.

The meteorological reason for this split comes down to a classic atmospheric tug-of-war involving the mid-tropospheric subtropical steering ridge. If the ridge stays strong, rigid, and flat over mainland India, it will act as a wall, blocking the November 1 depression from moving north and forcing it westward into Tamil Nadu to fuel the Northeast Monsoon. If an upper-level westerly trough approaches and breaks down the western edge of that ridge, a wide-open steering highway will clear out, allowing the depression to shoot straight north toward Odisha.

Bypassing Climatological Norms: The Threat of the Single-Digit Gap

The defining anomaly of this upcoming November 1 system is its extreme, near-instantaneous proximity to Cyclone Arnab. Climatological history dictates that the North Indian Ocean basin requires a prolonged "recharge window" to replenish atmospheric moisture and reset its thermodynamic boundaries. Historically, successive systems are separated by nearly a month:

·         Phailin to Depression BOB 05 (2013): A gap of 32 days separated the landfall of Phailin (October 12) from the genesis of the next depression (November 13).

·         Titli to Gaja (2018): A gap of 30 days passed between Titli’s landfall (October 11) and the organization of Cyclone Gaja (November 10).

·         Hamoon to Midhili (2023): Even in a highly active season, a gap of 22 days buffered Hamoon’s landfall (October 25) from Midhili’s formation (November 16).

 

The fact that the 2026 basin is generating a new depression within a single-digit gap of less than a week represents an alarming deviation from standard seasonal behavior.

This timeline is being artificially compressed by two powerful forces.

First, the active wave envelope of the Madden-Julian Oscillation (MJO) is remaining parked over Phase 3 (Indian Ocean) with an unusually high amplitude, continuously pumping spinning energy into the basin without its usual pause.

Second, because Arnab failed to churn up any cold sub-surface water, the typical 3-to-4 week thermal recharge period has vanished entirely.

Historical Precedent: The Legacy of Twin Cyclones

When evaluating what happens historically when a fresh tropical depression forms in quick succession right after a major cyclonic storm, the archives of the North Indian Ocean reveal definitive behavioral patterns.

Climatological history indicates that back-to-back systems rarely chart the exact same path. Instead, they almost always chart a new, distinct track due to two primary factors: Atmospheric Scarring and Ridge Realignment.

·         The Atmospheric Scarring Effect: A severe cyclone completely rearranges the moisture and temperature layout of the troposphere along its path. It leaves behind an atmospheric "scar" characterized by sinking air (subsidence) and disrupted wind patterns. A secondary system forming immediately afterward will naturally slide around this region of high stability, seeking an adjacent path where the air is still pristine, unstable, and ready to support rising cloud bands.

·        

The Mapped Trajectories of Past Twins: This was precisely the case in 2013 and 2018. When Cyclone Phailin made landfall near Gopalpur, Odisha (19.2°N, 84.9°E), its massive atmospheric outflow left an intense zone of descending dry air over the northern coast. When Depression BOB 05 organized a month later, it was forced away from Odisha, sliding far south to make landfall over Nagapattinam in Tamil Nadu (10.8°N, 79.8°E). Similarly, in 2018, after Cyclone Titli punched a hole through the subtropical ridge near Palasa, Andhra Pradesh (18.8°N, 84.4°E), the ridge quickly healed and built a wall over central India. This flattened the steering winds, forcing the fast-following Cyclone Gaja to march due west into Vedaranyam, Tamil Nadu (10.3°N, 79.8°E).

The only recent exception occurred during the 2023 season with Cyclones Hamoon and Midhili. In that instance, an approaching winter westerly trough overrode the atmospheric scarring effect, grabbing both systems in quick succession and pulling them along closely aligned, parallel tracks directly into Bangladesh.

Summary for Emergency Planners

The historical precedent strongly supports the split-arm scenario currently highlighted by the ECMWF model.

Because Cyclone Arnab will alter the upper-level atmospheric ridge as it moves inland over Central Andhra Pradesh, the secondary November 1 system is highly unlikely to repeat Arnab's exact track.

It will either find a way to break north into a brand-new sector of the Odisha/West Bengal coast as mapped by the NCMRWF, or it will be pushed far south into the Tamil Nadu basin.

For emergency managers, citizens, and municipal administrations across Bhubaneswar, Cuttack, Puri, and Berhampur, the core takeaway is clear: while Cyclone Arnab will strictly be a heavy waterlogging event rather than a high-wind threat for Odisha, the broader bay is locked in an incredibly active cycle.

With the ocean remaining super-heated and ready to support a brand-new low (may intensify to depression) by November 1, emergency preparations must look beyond the current weekly forecast.

It seems the end of October will not bring a total clearance of the skies, but rather a brief weather intermission before the next system takes shape!

Also Read: EXCLUSIVE | Cyclone Arnab Cloud Structure Revealed: 'Right Arm' to Bring Lashing Rains to Bhubaneswar, Cuttack – Check Timeline to Stay Safe