EXCLUSIVE| Inside Cyclone Arnab’s Machinery: Why Ocean Dynamics Are Drawing Very Severe Storm to Andhra Coast over Odisha

Bhubaneswar: The weather play for the brewing cyclone has been on full display. On the day a Low Pressure Area is born, it requires a vital connection to stay nourished and intensify.

For this developing system, an atmospheric trough running from the Arabian Sea across Kerala to coastal Tamil Nadu acts as an umbilical cord – extending up to 1.5 km to deliver a continuous supply of moisture and heat. This vital nourishment feeds the massive 5.8 km high vertical structure of the Bay of Bengal system, allowing it to rapidly draw energy from the sea.

As the machinery of the cyclone reaches its peak, real-time atmospheric shifts are simultaneously scripting its destiny.

According to IMD analyses, the upper air cyclonic circulations over Northeast Jharkhand and North Haryana/NW UP have "become less marked." By weakening, these systems have effectively cleared away localized wind variations and atmospheric resistance over northern and eastern India, allowing dominant steering winds to seamlessly pull the Bay of Bengal LPA in a clean, west-northwestward direction.

Meanwhile, a persistent cyclonic circulation over Northeast Bangladesh poses no threat of diversion. Extending up to only 0.9 km above mean sea level, it lacks the deep vertical stature required to alter steering currents or deflect the storm northward into West Bengal or Bangladesh.

The path ahead now looks clear. By remaining weak or localized, these secondary systems ensure the primary Bay of Bengal storm is unhindered by competing atmospheric forces, leaving it free to draw energy from open waters and advance directly toward the North Andhra Pradesh and adjoining South Odisha coasts.

 

To map this progression, the premier national forecaster – the Indian Meteorological Department (IMD) – has released the timeline of cyclone genesis on October 23.

 

·         October 24, 2026: The system is most likely to persist and intensify into a depression.

·         October 25, 2026: It is expected to move west-northwestwards and intensify further into a deep depression.

·         October 26, 2026: It is projected to strengthen into a cyclonic storm over the Westcentral Bay of Bengal.

·         Subsequent 2 Days: It will continue to intensify and head toward the North Andhra Pradesh and adjoining South Odisha coasts.

Even as the IMD has indicated that the Cyclonic storm will be tracking towards the North Andhra Pradesh and adjoining South Odisha coasts, the atmospheric conditions prior to the landfall day of Oct 28 clearly maps the landfall place – the very severe cyclonic storm tracking towards.  

Cyclone Arnab To Brew as Very Severe Cyclonic Storm?

With the IMD officially declaring that a cyclonic system is brewing over the Bay, this system will go by the name of Cyclone Arnab (meaning "The Ocean"), a title contributed by neighbouring Bangladesh. True to its name, the brewing process of Cyclone Arnab has literally been set in motion across the deep ocean waters, drawing its formidable strength from the very element it is named after.

 

Cyclone Arnab seems entirely determined to brew up as atleast a Very Severe Cyclone.

 

The IMD classifies a Very Severe Cyclonic Storm (VSCS) as a system with maximum sustained 3-minute surface winds between 64 and 89 knots (118 to 166 km/h).

Though IMD has clearly declared that the after becoming cyclonic storm on October 26, it will undergo further intensification on Oct 27 and 28, before landfall, country’s premier oceanic research institute INCOIS projects the peak wind speed of the system at 28 to 30 m/s (~54 to 58 knots or 100 to 108 km/h) that falls just shy of the official threshold, placing it at the upper limit of a Severe Cyclonic Storm (SCS) (48–63 knots).

 

However, ECMWF projects the core boundary wind field of 60 knots that sits right on the cusp of a VSCS (very severe cyclonic storm).

 

However, looking at the broader environmental factors and recent analytical runs, global numerical models (including ECMWF and NCMRWF) show structural capabilities that could push the system well into Extremely Severe Cyclonic Storm (ESCS) territory (90 to 119 knots) while out at sea.

 

As the system would be tapping into the 30°C+ thermal fuel reservoirs off the Andhra coast, and the projection is, the boundary layer winds are primed to easily cross that 64-knot threshold, officially pushing the "cyclone play" into at least Very Severe lifecycle phase.

 

An interesting oceanic fact here also indicates where the system would be heading.

 

The INCOIS oceanic data shows that the ocean waters directly off the coast of Odisha and West Bengal show a distinct cooling sign. The temperatures are projected around 27.5°C to 28.5°C.

 

An analysis shows that the cooler pool off Odisha is likely a result of two factors:

·         Early winter cooling (as northern continental winds start blowing over the bay) and

·         Tropical upwelling from the outer bands of the expanding storm system itself.

 

Whatever be the case, as the northern waters are slightly less thermal-dense, this indicate why the storm is being drawn toward the high-energy reservoir in the west-central Bay (AP coast) rather than recurving cleanly into the northern coast (Odisha).

 

Cyclone Arnab May Hit Kakinada

 

Even as the IMD has today indicated that the severe cyclonic system would be tracking towards the North Andhra Pradesh and adjoining South Odisha coats, there has been a multi model consensus on the precise landfall place of Cyclone Arnab.

India’s ace weather model developers and research institutes like NCMRWF and INCOIS, along with global weather forecaster ECMWF and NCEP GFS, have agreed on the precise target area. The exact location marked by the model runs has been around 16.96°N, 81.81°E.

All models agree on the weather fact that the Coastal Andhra Pradesh would be the landfall place of Cyclone Arnab.

 

They see Arnab eyeing on the East Godavari / Eluru district boundary area, situated just north of Rajamundhry region and a short distance inland from the coastline near Kakinada.

 

Arnab’s Fury on Kakinada Will be Extreme

An analysis of the accompanying vertical profile shows intense atmospheric saturation:

·         Precipitable Water (PWAT): A massive 2.93 inches, indicating an exceptionally moisture-dense atmospheric column ready to unleash torrents of rain.

·         Relative Humidity (RH): Sitting at a staggering 98% in the mid-lower troposphere (300–850mb).

·         Wind Shear (SHR 200-850mb): A high value of 76 knots, signaling that while the storm is dumping phenomenal rainfall right over Kakinada, it will also face strong upper-level winds that may begin displacing its core structures as it interacts with the terrain.

 

The Twist in the Warning

 

IMD has put the coastal Andhra Pradesh in red zone on October 27, 24 hours exactly Arnab making landfall over Kakainada.

 

The Red Warning for Coastal AP on October 27 highlights that the highest tier of life-threatening weather (extremely heavy rain and destructive winds) will hit the AP coast first as the system makes its final approach.

 

But on landfall day, IMD has downgraded the warning for coastal AP to Orange.

 

The meteorological reason behind this twist is the severe disruption and displacement of the cyclone's vertical structure caused by the high vertical wind shear moving over land, effectively tearing the core apart as it makes impact.

Also Read:EXCLUSIVE| Another Cyclone Titli Loading in Bay; Landfall Likely on Oct 28 Between Macchilipatnam and Vishakapatnam!