Friday, March 24, 2017

Here's Why There's More Than One Type of Tornado

Chris Dolce
Published: March 23,2017

There are many terms meteorologists and storm chasers use to describe different types of tornadoes. You may have heard of a wedge tornado or a landspout, but what do they mean?
To answer that question, here's a closer look at the different types of tornadoes you may hear about.
(MORE: Tornado Central)

Wedge Tornado

Wedge tornado is a slang term used by meteorologists and storm spotters to describe a wide tornado, but not every large tornado is considered a wedge.
In general, a wedge tornado should be "at least as wide (horizontally) at the ground as it is tall (vertically) from the ground to cloud base," according to the National Weather Service.
Many wedge tornadoes are violent, causing EF4 or EF5 damage, but not all of them are that strong. An example of a wedge tornado is the EF5 that struck Joplin, Missouri, in May 2011.
A wedge tornado about a mile wide near Binger, Oklahoma, May 22, 1981. It produced F4 damage along its path. (NOAA)

Multi-Vortex Tornado

As the name implies, this tornado has multiple vortices rotating around a center of a larger tornado circulation.
These so-called suction vortices are occasionally visible if the larger tornado circulation doesn't have too much debris to obscure them. The Storm Prediction Center says multi-vortex tornadoes are capable of causing "narrow, short, extreme swaths of damage that sometimes arc through tornado tracks."
A tornado that struck El Reno, Oklahoma, on May 31, 2013 is an example of this type of tornado and featured intense vortices within its larger circulation. Mobile Doppler Radar measured winds of 200 mph or greater associated with those vortices, illustrating how they can cause smaller areas of extreme damage.
(MORE: Suction Swaths From Multi-Vortex Tornado in 2016)

A model of a multi-vortex tornado.

Rain-Wrapped Tornado

This type of tornado is obscured by heavy rainfall, and sometimes it's impossible to know if a twister is there unless verified by radar or other sources.
Rain-wrapped tornadoes are associated with high-precipitation supercell thunderstorms or can be embedded within squall lines (a line of intense thunderstorms).
A rain-wrapped tornado near Tipton, Oklahoma, May 20, 1977. The existence of a tornado hidden behind the rain is verified in this photo by the power flash seen at the bottom of the image. (NOAA)

Cone and Stovepipe Tornadoes

These two types of tornadoes are probably the most familiar and are visually similar.
The cone tornado is wider at the base of the clouds and narrower near where it touches the ground, which is how most people think of a tornado's appearance in a traditional sense.
A stovepipe tornado is about as wide near the cloud base as it is along the ground. They are tall and narrow, just like a stovepipe.
A cone tornado in Wyoming on June 5, 2009. (Sean Waugh, NOAA/OAR/NSSL)

Landspout Tornado

A landspout is a tornado that does not develop from a supercell thunderstorm as a wedge or cone tornado would.
Instead, they form when a developing towering cumulus cloud occurs over any near-surface boundary of converging winds. In other words, the area of rotation originates near the surface rather than aloft. That rotating air is stretched vertically and eventually grows into a landspout.
(MORE: See Difference Between a Landspout and a Tornado)

A landspout near North Platte, Nebraska, on May 22, 2004. (Wikimedia Commons)


A waterspout is also a type of tornado and is essentially a landspout over water. As described above, the source of spin for their development is near the surface rather than aloft.
The warm waters surrounding Florida provide warmth and moisture for growing clouds that can commonly spawn waterspouts. Those waterspouts mostly stay over the open water as a hazard to mariners.
When waterspouts form from thunderstorms, however, they can track onshore and produce damage.
A waterspout off the Florida Keys on Sept. 10, 1969. (Dr. Joseph Golden, NOAA)

Rope Tornado

Sometimes you'll hear meteorologists or storm spotters say, "The tornado is roping out."
This is a reference to a tornado ending its life cycle where it appears as a rope-like appendage hanging from the cloud base. Though the so-called rope tornado may appear narrow and more elongated horizontally than earlier in its life cycle, it's still capable of significant damage on the ground until it ends.
Once the tornado has dissipated, a new twister could develop from the same supercell thunderstorm should a new area of rotation form.
A tornado in its rope stage over the Plains in May 2008. (Sean Waugh NOAA/NSSL)


Having the "nado" in gustnado would suggest this is a type of tornado, but it's not.
A gustnado is a small and typically weak area of spin on the leading edge of a thunderstorm outflow. Since gustnadoes are not connected to any cloud base, they are not considered tornadoes.
They are sometimes reported as tornadoes, given their appearance on the ground. Gustnadoes can also cause minor damage.
To see what a gustnado looks like, check the video at the link below.
(MORE: Gustnado in Kansas)

MORE: Strange Tornado Damage

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