Are gustanado considered tornadoes or not?

[Eric Flescher]

In 2001, with Doug Rafik in Texas, I photographed what looked to be a tornado. Many said it was , others said it was a GUSTANADO others call it a LANDSPOUT.
Since then I have seen , photographed and videotaped more GUSTANADOES like many of you.
I noticed this on
www.srh.noaa.gov/hgx/climate/reviews/100504pns.txt (http://www.stormtrack.org/forum/www.srh.noaa.gov/hgx/climate/reviews/100504pns.txt)
A GUSTANADO IS A SMALL TORNADO THAT SOMETIMES
FORMS ALONG THE LEADING EDGE OF A THUNDERSTORM AND CAN ALSO PRODUCE DAMAGE AND ARE NORMALLY SHORT LIVED.

(1) is a GUSTANADO counted as a tornado or not? why or why not?
(2) anything more related to their creation, attachment to cloud base etc information ?

thanks

[Greg Blumberg]

In my experience a gustnado is a small vortex of spinning air that is caused by the gust fronts in thunderstorms. So, a gustnado is more like a whirlwind spun up by the air currents around a thunderstorm. It is not attached to the cloud base.

A landspout however, is attached to the cloud base and is associated with the updraft of the cloud (usually cumulus congestus), but the updraft is not rotating (associated with a mesocyclone).

A tornado is attached to the base of the cloud and is associated with the mesocyclone of a thunderstorm.

I believe that landspouts are considered tornadoes by the NWS, but I'm not sure. I'm pretty sure gustnadoes aren't included in that category. Probably because they're difficult to keep track of and don't normally do a lot of damage. I'm almost positive this is the distinction between these three different phenomena, however.

[Paul Knightley]

There are many whirlwinds which can develop around thunderstorms. IMO, a tornado is an inflow/updraught phenomenon - whether or not it develops beneath a mesocyclone shouldn't change its name, although it is obviously useful to prefix the word "tornado" with words like "non-meso", "meso", or whatever. "Gustnadoes" are whirlwinds which form at the leading edge of outflow and are not updraught-related. Thus, IMO, they should not be considered tornadoes. However, small whirls may develop on the RFD of a supercell, and then get ingested into the updraught region, and then stretched, and become tornadoes.

[Eric Flescher]

Gustanadoes are not tornadoes but landspouts might be
What is the difference ?

[Laura Duchesne]

Gustnadoes aren't attached to the base of a storm, it is just ground circulation caused by the inflow/outflow winds along the leading edge of a gust front, so therefore I don't consider them tornadoes.

[david diehl]

According the the Warning Coordinating Meterogist at the NWS in Northern Indiana,
Gustnadoes are to be reported as Tornadoes due to the fact that they can cause up to EF-0 damage.
I found this kind of interesting, but if it is what they want, it is what they get

[Bobby Prentice]

According to the American Meteorology Society (AMS) Glossary of Meteorology (http://amsglossary.allenpress.com/glossary/), gustnado (http://amsglossary.allenpress.com/glossary/search?id=gustnado1), landspout (http://amsglossary.allenpress.com/glossary/search?id=landspout1), and waterspout (http://amsglossary.allenpress.com/glossary/search?id=waterspout1)are all tornado (http://amsglossary.allenpress.com/glossary/search?id=supercell-tornado1)es. Some National Weather Service (http://www.nws.noaa.gov/) references say a gustnado (http://amsglossary.allenpress.com/glossary/search?id=gustnado1) is a tornado (http://amsglossary.allenpress.com/glossary/search?id=supercell-tornado1), while others say not. Most storm chasers do not count a gustnado (http://amsglossary.allenpress.com/glossary/search?id=gustnado1) as a tornado (http://amsglossary.allenpress.com/glossary/search?id=supercell-tornado1).


tornado—1. A violently rotating column of air, in contact with the ground, either pendant from a cumuliform (http://amsglossary.allenpress.com/glossary/search?id=cumuliform1) cloud or underneath a cumuliform cloud, and often (but not always) visible as a funnel cloud (http://amsglossary.allenpress.com/glossary/search?id=funnel-cloud1).

When tornadoes do occur without any visible funnel cloud, debris at the surface is usually the indication of the existence of an intense circulation (http://amsglossary.allenpress.com/glossary/search?id=circulation1) in contact with the ground. On a local scale (http://amsglossary.allenpress.com/glossary/search?id=scale1), the tornado is the most intense of all atmospheric circulations. Its vortex (http://amsglossary.allenpress.com/glossary/search?id=vortex1), typically a few hundred meters in diameter, usually rotates cyclonically (on rare occasions anticyclonically rotating tornadoes have been observed) with wind speeds (http://amsglossary.allenpress.com/glossary/search?id=wind-speed1) as low as 18 m s⁻¹ (40 mph) to wind speeds as high as 135 m s⁻¹ (300 mph). Wind speeds are sometimes estimated on the basis of wind damage using the Fujita scale (http://amsglossary.allenpress.com/glossary/search?id=fujita-scale1). Some tornadoes may also contain secondary vortices (suction vortices (http://amsglossary.allenpress.com/glossary/search?id=suction-vortices1)). Tornadoes occur on all continents but are most common in the United States, where the average number of reported tornadoes is roughly 1000 per year, with the majority of them on the central plains and in the southeastern states (see Tornado Alley (http://amsglossary.allenpress.com/glossary/search?id=tornado-alley1)). They can occur throughout the year at any time of day. In the central plains of the United States they are most frequent in spring during the late afternoon. See also supercell tornado (http://amsglossary.allenpress.com/glossary/search?id=supercell-tornado1), nonsupercell tornado (http://amsglossary.allenpress.com/glossary/search?id=nonsupercell-tornado1), gustnado (http://amsglossary.allenpress.com/glossary/search?id=gustnado1), landspout (http://amsglossary.allenpress.com/glossary/search?id=landspout1), waterspout (http://amsglossary.allenpress.com/glossary/search?id=waterspout1). 2. A violent thundersquall (http://amsglossary.allenpress.com/glossary/search?id=thundersquall1) in West Africa and adjacent Atlantic waters.


waterspout—1. In general, any tornado (http://amsglossary.allenpress.com/glossary/search?id=tornado1) over a body of water. 2. In its most common form, a nonsupercell tornado over water.

Such events consist of an intense columnar vortex (usually containing a funnel cloud) that occurs over a body of water and is connected to a cumuliform cloud. Waterspouts exhibit a five- stage, discrete life cycle (http://amsglossary.allenpress.com/glossary/search?id=cycle1) observable from aircraft: 1) dark-spot stage; 2) spiral pattern stage; 3) spray-ring stage; 4) mature or spray-vortex stage; and 5) decay stage. Waterspouts occur most frequently in the subtropics (http://amsglossary.allenpress.com/glossary/search?id=subtropics1) during the warm season (http://amsglossary.allenpress.com/glossary/search?id=season1); more are reported in the lower Florida Keys than in any other place in the world. Funnel diameters range (http://amsglossary.allenpress.com/glossary/search?id=range1) from a few up to 100 m or more; lifetimes average 5–10 minutes, but large waterspouts can persist for up to one hour.


landspout—1. (Rare.) A tornado (http://amsglossary.allenpress.com/glossary/search?id=tornado1). 2. Colloquial expression describing tornadoes occurring with a parent cloud (http://amsglossary.allenpress.com/glossary/search?id=cloud1) in its growth stage and with its vorticity (http://amsglossary.allenpress.com/glossary/search?id=vorticity1) originating in the boundary layer (http://amsglossary.allenpress.com/glossary/search?id=boundary-layer1).

The parent cloud does not contain a preexisting midlevel mesocyclone (http://amsglossary.allenpress.com/glossary/search?id=mesocyclone1). The landspout was so named because it looks like a weak, Florida Keys waterspout (http://amsglossary.allenpress.com/glossary/search?id=waterspout1) over land. See nonsupercell tornado (http://amsglossary.allenpress.com/glossary/search?id=nonsupercell-tornado1).

Bluestein, H. B., 1985: The formation of a “landspout” in a “broken-line” squall line in Oklahoma. Preprints, 14th Conf. on Severe Local Storms, Indianapolis, 267–270.


gustnado—Colloquial expression for a short-lived, shallow, generally weak tornado (http://amsglossary.allenpress.com/glossary/search?id=tornado1) found along a gust front (http://amsglossary.allenpress.com/glossary/search?id=gust-front1). Gustnadoes are usually visualized by a rotating dust (http://amsglossary.allenpress.com/glossary/search?id=dust1) or debris cloud.

See nonsupercell tornado (http://amsglossary.allenpress.com/glossary/search?id=nonsupercell-tornado1).


Gustnado (http://www.srh.noaa.gov/oun/severewx/glossary2.php#Gustnado) (or Gustinado) - [Slang], gust front tornado. A small tornado (http://www.srh.noaa.gov/oun/severewx/glossary4.php#Tornado), usually weak and short-lived, that occurs along the gust front (http://www.srh.noaa.gov/oun/severewx/glossary2.php#Gust%20Front) of a thunderstorm. Often it is visible only as a debris cloud (http://www.srh.noaa.gov/oun/severewx/glossary2.php#Debris%20Cloud) or dust whirl (http://www.srh.noaa.gov/oun/severewx/glossary2.php#Dust%20Whirl) near the ground. Gustnadoes are not associated with storm-scale (http://www.srh.noaa.gov/oun/severewx/glossary4.php#Storm-scale) rotation (i.e. mesocyclones (http://www.srh.noaa.gov/oun/severewx/glossary3.php#Mesocyclone)); they are more likely to be associated visually with a shelf cloud (http://www.srh.noaa.gov/oun/severewx/glossary4.php#Shelf%20Cloud) than with a wall cloud (http://www.srh.noaa.gov/oun/severewx/glossary4.php#Wall%20Cloud).


What is a gustnado? (http://www.spc.noaa.gov/faq/tornado/#gustnado1) A gustnado is a small and usually weak whirlwind which forms as an eddy in thunderstorm outflows. They do not connect with any cloud-base rotation and are not tornadoes. But because gustnadoes often have a spinning dust cloud at ground level, they are sometimes wrongly reported as tornadoes. Gustnadoes can do minor damage (e.g., break windows and tree limbs, overturn trash cans and toss lawn furniture), and should be avoided.