Arnab Threatens India, In-Fa moves Towards the Mariana Islands: AI Models Discussion 10-26-26

We will go west to east across the Northern Hemisphere and take a look at a few tropical cyclones, starting with one that is threatening a populated coastline.

Indian Ocean

As models were hinting at last week, Arnab (02B) has formed in the Bay of Bengal. The cyclone is intensifying despite some easterly shear, and models show it intensifying further over the next couple of days (Figure 1).

The TC is forecast to move west towards the coast, but then may do a stall or loop offshore before turning north. This erratic motion is due to an interaction with another area of vorticity (spin to the south of the storm), as well as the influence of a mid-to-upper-level trough to the west of the storm (Figure 2).

The storm appears poised to intensify quickly in the short-term, with fairly light upper-level winds and warm water to work with. Near landfall, we could see some weakening due to southeasterly shear (Figure 3), but Arnab will likely still be a strong TC as it approaches India. And the slow motion could prolong impacts and increase flooding along parts of the coast.

West Pacific

The big system in the West Pacific right now is Typhoon In-Fa, which is moving west as a Category-4-equivalent typhoon, and forecast to remain as a powerful TC and move through the Mariana Islands (Figure 4). Right now, the forecast takes it north of the more populated islands like Guam and Saipan, but people there should still keep a close eye on it.

In the medium range, In-Fa is likely to recurve well before reaching Taiwan or Japan, as the jet stream dips further south with fall in full swing (Figure 5).

East Pacific

The East Pacific is currently quiet, with Tropical Depression Olana about to dissipate well west of Hawaii and Tropical Storm Vance weakening southwest of Mexico. There is some signal for another TC to develop south of Hawaii in the coming days, and perhaps another system south of Central America (Figure 6). We’ll keep an eye on these chances over the next week or so.

Atlantic

The Atlantic is quiet as it has been for much of the season, and that looks to continue as we head into the final month of the 2026 season. There are some weak signals for a subtropical system to develop in the SW Atlantic (Figure 7), but nothing coherent at this point. It’s quite possible the Atlantic is mostly or totally finished for the year as El Niño continues to dominate.

We’ll see how these systems evolve in the coming days, and be back with another update soon!