Matthew Cappucci @MatthewCappucci
Incredible — the Hurricane Hunters just found a SQUARE eyewall on radar inside Melissa.
This is because of multiple “mesovortices,” or smaller-scale eddies/whirls, inside the eye.
The buzzsaw-like eyewall, with winds likely in the Category 4 range, has an INCREDIBLE amount of angular momentum as it whirs round and round rapidly. But in the eye, it’s calm.
The inner edge of the eyewall chafes against the calm eye, causing portions of the eyewall to curl back on itself. That helps flux angular momentum (spin momentum) into the eye itself.
The atmosphere doesn’t like discontinuities… and going from extreme wind to calm is an abrupt transition. Mesovortices help balance that.
But a SQUARE eyewall? Something only seen in the strongest hurricanes — and usually those undergoing extreme rapid intensification.
1:32 AM · Oct 26, 2025
https://x.com/MatthewCappucci/status/1982319383364940198