Origin and Formation#

Cyclone Shakhti originated from the remnants of an invest carrying the moniker of BOB-06, which formed over the Bay of Bengal in late September 2025. The disturbance didn’t develop into a tropical cyclone, however after coming ashore over the Indian subcontinent, it began organizing as a fairly rare inland depression.

The tropical low slowly drifted westward toward the Arabian Sea, eventually coming to a stop just inland in Gujarat; an Indian state. By this time the system was designated a tropical depression, as it possessed a low level center, as well as firing organized deep convection. The TD remained stationary over the area, periodically producing convective bursts near its LLC.

Models, as usual in this basin, were very unsure as to what exactly would happen with the storm. Some ensemble groups, such as the Google DeepMind models predicted the storm to intensify steadily and become a solid category 1 or 2 equivalent cyclone, while others, most notably the GEFS group did not show any development for Shakhti.

Looking at it objectively, it was obvious model biases were heavily influencing what they were predicting for Shakhti. NWPs showed the storm to be a disorganized mess by the coast, yet on the 30th it already possessed a solid LLC while firing DMC - clear signs of a TC brewing.

Shakhti officially formed on the 1st of October. At this time the storm remained pretty messy, however it was steadily improving. Deep moist convection was shackled mainly to the southern quadrant of the storm as northerly shear pushed on the system.

Dry air - the main factor limiting formation of TCs in this basin - was not that bad at the time of Shakhti’s formation, as most of the basin was enjoying a moist plume brought on by the airmass associated with BOB-06, and in its center was Shakhti.

Intensification#

Shakhti began organizing more on the 2nd, especially in the later half of the day. Convection began firing more often in tandem with shear lessening, allowing for the CBs to wrap around the cyclone’s core, especially on the northern side, which used to be fully exposed.

A microwave pass taken around midnight of the 2nd/3rd indicated that the storm was in the process of building a solid low level core - the eyewall had mostly closed while rain bands curled around it - all signs of a freshly developing cyclone.

The cyclone began intensifying at a more rapid pace during the later half of the 3rd of October. Cloud tops cooled to the -80C range, outflow began propagating radially, and especially poleward - shear was lessening rapidly, and thus giving Shakhti a chance to form a more organized CDO.

One of the main things which helped the cyclone in organizing was a DMAX diurnal burst - around sunset to early night every day, the latent heat release changes to be more easily propagated into the atmosphere, causing a large burst of activity, especially seen by the expansion of the cirrus canopy. Shakthi was undergoing such a burst, which helped it overcome shear.

Peak Intensity#

Shakhti intensified quite quickly on the morning of the 4th, rapidly developing an eye which maintained itself for a brief period. At this time the storm was likely stronger than the official estimate of a low-end category 1 equivalent cyclone, with SATCON data nearing category 2.

The eye did not manage to sustain itself and throughout its existence the feature was ragged in appearance. Despite this, the eye became quite warm and somewhat dry at one point, reaching a temperature of 11.6C on infrared, and a mediocre value of -33C on water vapor.

The eye did not collapse in a traditional weakening manner - instead, as it is typical with weak storms another convective burst fired within the eyewall, promptly obscuring the eye with cirrus clouds.

Worth noting is that during the time of Shakhti’s peak, we got a lucky microwave pass! What it showed was that despite the storm having a core, it was not fully closed, most likely due to some dry air entrainment eroding the eyewall.

Soon after attaining peak intensity Shakhti began struggling with… as expected: dry air.

Northerly shear increased once more, which in turn caused dry air from the Arabian peninsula and Iran to be forced into the storm at a rapid pace, causing all of the deep moist convection to become confined to the southern quadrants of the storm.

Microwave imagery continued to show the erosion of the eyewall, proving that it was indeed dry air choking the system out. At this point, with forecasts showing an increase in shear, we knew Shakhti was not going to get back to its peak intensity, however the rest of its life was still fascinating.

Weakening#

Following the cyclone’s peak on the 4th of October, convection began waning. Around mid day on the 5th what was left of the storm was a single area of centralized convection - the eye feature now long gone.

Due to a sudden burst of shear, and, in turn, dry air, Shakhti experienced a convective collapse. The entire CDO quickly warmed with only wispy cirrus remaining. Thanks to the force with which the convection previously fired the cirrus was spreading radially, including up shear, however when the shear picked up outflow lost its upward motion, forming a crescent shape made of cirrus clouds around the decaying CDO.

When the shear massacre ended what was left of the cyclone was a ghastly low level center spinning away aimlessly, now only guided by low level winds. This was also evident in microwave imagery, which showed an almost inverted view of the storm, with the center containing the highest Kelvin values in the area.

Soon thereafter on the 6th of October Shakthi made an attempt at re-intensifying, however it did not stand a chance against the brisk northeasterly wind blowing directly over its center. The convective burst that fired quickly dissipated, and the cyclone was once again left exposed.

Between the 7th and 9th, Shakthi remained convectionless, with only singular thunderstorms popping up occasionally on its periphery. At this point, everyone though that this system was toast, however, it made one last attempt at strengthening on the morning of the 10th.

A large cluster of convective cells popped up in 3/4ths of the storm, producing a bizarre image in RGB water vapor imagery, as the entire region was covered with extremely dry air, with only said thunderstorms appearing around the LLC.

Weak Remains and Dissipation#

Shakhti’s last breath occurred on the 11th of October after the thunderstorms from the previous day maintained themselves and eventually coalesced into one CB, which thanks to its vertical height quickly began feeling the heavy shear, now coming from the southeast.

The CB followed the pattern the previous attempts did, evaporating into a swirl of cirrus clouds after existing for a few hours.

Despite IMD and JTWC officially designating Shakhti as dissipated on the 11th of October, Shakthi’s ghastly remains continued drifting for a while in the western portions of the Arabian sea, with ASCAT data supporting ~25 knot winds.

While nearing the Red sea, Shakhti produced its last bursts of convection - singular towers which briefly reached -60c, then dissipated less than an hour later.

Gallery of valuable data, imagery and extra stuff.#