Multi-Vortex Tornadoes — Why Some Tornadoes Have Multiple Funnels
What is a multi-vortex tornado?
A multi-vortex tornado is a single tornado that contains two or more smaller vortices, called "suction vortices," rotating inside the parent circulation. Each suction vortex spans roughly 10 to 100 feet in diameter and rotates in addition to the parent tornado, so a point on the ground experiences both motions at once. This is why multi-vortex tornadoes produce the most extreme wind speeds on record and the streaky damage patterns where one house is leveled and a neighbor 30 feet away is barely touched.
How does a multi-vortex tornado form?
Most tornadoes start with a single vortex — a column of rotating air. As the parent vortex strengthens and the radius of maximum wind contracts, the airflow becomes unstable and breaks up into smaller, faster-rotating sub-vortices that orbit inside the parent. This is called vortex breakdown, and it's been observed in laboratory experiments and on storm-chase video.
The number of sub-vortices depends on the parent tornado's swirl ratio (a measure of rotational vs. inflow energy). Typical multi-vortex tornadoes have 2 to 6 sub-vortices. Famous examples — like the 1999 Bridge Creek-Moore F5, the 2011 El Reno EF3, and the 2013 Moore EF5 — all showed multi-vortex structure on radar and survey.
Why do multi-vortex tornadoes cause streaky damage?
The damage pattern is the diagnostic signature. A point on the ground only experiences extreme winds when a sub-vortex passes directly over it. Between sub-vortices, winds drop to "merely" hurricane-force. So as the parent tornado tracks across a neighborhood, the sub-vortices carve narrow streaks of EF4 or EF5 damage through a wider corridor of EF1 or EF2.
This is why post-tornado photos sometimes show a leveled house next to one with intact walls. Both were inside the parent tornado's circulation; only one was hit by a sub-vortex. The 2013 Moore EF5 produced visible streak patterns over a mile wide — a hallmark of the multi-vortex regime.
What wind speeds do multi-vortex tornadoes produce?
The fastest wind speeds ever measured in a tornado came from sub-vortex passes. The 1999 Bridge Creek-Moore tornado had a Doppler-on-Wheels measurement of 302 mph (±20 mph), and the 2013 El Reno tornado measured 295-336 mph in a sub-vortex. These are roughly 50-100 mph faster than what the parent circulation alone produces.
The Enhanced Fujita scale tops out at EF5 (over 200 mph estimated). Sub-vortex peaks exceed the EF scale's measurement framework — the official EF rating reflects damage indicators on the ground, not Doppler readings, but the discrepancy is part of why some meteorologists call for a research-grade scale above EF5.
How do multi-vortex tornadoes look from the ground?
From a distance, a multi-vortex tornado often looks like one wide funnel. Up close — the perspective storm chasers risk to capture — you see two or more thin "rope" tornadoes orbiting each other inside the parent, like braided ropes. Some chasers describe it as "spiders" of dust kicking up around the main funnel base.
Not every wide tornado is multi-vortex. A "wedge" tornado may be a single broad vortex (the 1957 Fargo F5, for example). The distinction is structural: multi-vortex requires discrete sub-vortices visible on Doppler radar or in clear video; a wide single-vortex tornado has continuous rotation across its width.
Are horizontal vortices the same thing?
No. Horizontal vortices are spinning tubes of air parallel to the ground, often associated with strong downbursts or roll clouds. They are not tornadoes — tornadoes are vertical (or near-vertical) vortices that connect a thunderstorm to the surface. Horizontal vortices can produce damaging straight-line winds and are sometimes mistaken for tornadoes by witnesses.
Some thunderstorms can tilt a horizontal vortex into a vertical one — this is the textbook tornado-formation process via low-level mesocyclone. So horizontal vortices feed tornado formation, but they aren't tornadoes themselves and don't have the multi-vortex sub-structure.