Storm science

Multi-vortex tornadoes

Some tornadoes look like several tornadoes braided together. That's because they are — smaller intense vortices dancing around a common center of rotation. Here's the science.

The definition

A multi-vortex tornado has 2-7 smaller vortices, called subvortices or suction vortices, rotating around a common center of rotation. The parent circulation looks like a tornado; the subvortices ride within it.

Subvortices carry the peak winds. When a subvortex sweeps across a house, damage can be EF5 within a swath just 30 feet wide, while adjacent homes have EF2 damage.

How they form

A parent circulation (mesocyclone-derived) develops.
The parent updraft intensifies rapidly.
Rossby-like waves organize the peripheral high-wind zone into discrete cores.
Each core carries angular momentum and behaves like a mini-tornado.
Multiple cores rotate around the parent axis at 100-300 mph.
Cores form, dissipate, and reform on scales of 5-30 seconds.

Famous multi-vortex events

1974 Xenia, Ohio (F5)

Some of the earliest scientific observation of subvortex damage.

1999 Bridge Creek-Moore F5

DOW measured 301 mph in a subvortex.

2007 Greensburg, KS EF5

Wide wedge with visible subvortex structure.

2011 El Reno EF3 (May 24)

Dramatic multi-vortex phase filmed by many chasers.

2011 Joplin EF5

Interior of the wedge showed multiple subvortex swaths.

2013 El Reno EF3

Chased by TWISTEX; the multiple vortex phase killed Tim Samaras and team.

2013 Moore EF5

Damage swath variability suggests strong subvortex activity.

2020 Nashville EF3

HP embedded multi-vortex.

2023 Rolling Fork EF4

Multi-vortex phase caught by chasers.

Damage patterns

Cycloidal (looping) marks in fields — signature of subvortex sweep.
Ripped houses next to intact homes in the same subdivision.
Vehicles thrown 500+ feet in specific zones.
Tree stripping vs adjacent standing trees.
Damage indicators inconsistent within the same rating zone — a puzzle for EF-scale surveys.

The physics: Fujita's "Suction Vortex" concept

Ted Fujita proposed the suction vortex concept in the 1970s. He noticed that damage in the 1974 Xenia tornado had loops carved into fields.

He hypothesized that concentrated small-scale vortices swept along the ground within the larger parent circulation.

Later mobile radar and photography confirmed the hypothesis.

The chaser view

Multi-vortex tornadoes look ropy, braided, "dancing."
Individual subvortices are dust plumes on the ground.
Cores can appear/disappear on video every few seconds.
Photos from directly downstream (low visibility angle) look normal — beauty shot from the side.
Multi-vortex phases can last 30 seconds to 5 minutes.
A tornado can enter and exit multi-vortex phases multiple times in its life.

Satellite tornadoes vs subvortices

Subvortex

Inside the parent circulation. Same rotation direction. Feeds parent.

Satellite tornado

Independent tornado outside the main circulation. Same mesocyclone but different vortex.

Satellite tornadoes are much rarer than subvortices. Famous cases: 2011 Tuscaloosa-Birmingham (multiple satellites documented).

Twin tornadoes

Twin tornadoes are two independent tornadoes from the same supercell. Well-known cases:

2014 Pilger NE (June 16) — twin EF4s side by side.
1965 Palm Sunday outbreak — multiple twin tornadoes.
2004 Roanoke, IL — filmed twin tornado.
Twin tornadoes have historically been called "sisters" or "dyads" by observers.

Why multi-vortex tornadoes matter for safety

A tornado rated EF3 might contain EF5 subvortex swaths.
Being in the "outer" zone of a wedge does NOT guarantee lower damage.
Storm shelters even in the center of a wedge tornado footprint save lives.
Path variability makes damage surveys and warnings both harder.
Chasers should never assume distance from parent tornado equals safety.