Glossary of tornado terms

From Wikipedia the free encyclopedia

The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.











  • In situ
  • Inflow
  • Inflow jet
  • Inflow notch
  • Instability
  • Intense tornado – A tornado rated F3-F5 or EF3-EF5.
  • Institute for Disaster Research (IDR)











  • Safe room
  • Satellite tornado – A smaller tornado that orbits a primary tornado associated with the same mesocyclone.
  • Scouring – Term used when soil and dirt is pulled from the surface after a tornado.
  • Scud (Scattered Cumulus Under Deck)
  • Severe local storm (SLS) – A thunderstorm presenting severe characteristics in a localized area.
  • Severe Local Storms Unit (SELS) – A team of National Weather Service experts tasked with forecasting convective weather. It was eventually included as a unit within the NSSFC.
  • Severe thunderstorm (svr) – A hazardous thunderstorm capable of causing injury or damage. The U.S. National Weather Service defines a severe thunderstorm as one producing 58 mph (93 km/h) or greater winds, 1 in (2.5 cm) or larger hail, or producing a funnel cloud or tornado.
  • Shallow convection – Occurs when convective instability exists, but no convection occurs
  • ShearWind shear – Winds aloft, often measured in knots.
  • Shear funnel – Brief, often weak funnel generated by shear in a thunderstorm.
  • Shelf cloud – Generally associated with strong thunderstorms, found along the leading edge. Horizontal and dark in appearance.
  • Shortwave trough – Embedded kink within seen in overall troughing patterns.
  • Significant tornado – A substantial tornado, one that is rated F2-F5 or EF2-EF5. Grazulis also includes (E)F0-(E)F1 tornadoes that cause a fatality in his definition for The Tornado Project database.
  • Significant tornado parameter (STP) – Model parameter calculated using Shear values, Instability values, and vorticity values.
  • Skipping tornado – Often considered a Multi-vortex tornado.
  • Skywarn – The storm spotting program of the US National Weather Service. Skywarn organizations have also been formed in Europe. The Canadian program is Canwarn.
  • Slight risk (SLGT)
  • Space Science and Engineering Center (SSEC)
  • Speed shear
  • Spin-up – A small, ephemeral vortex. These can refer to tornadoes spawned by quasi-linear convective systems or tropical cyclones, which occasionally become strong and fairly long track. A spin-up may sometimes refer to a landspout or gustnado (the latter of which is rarely an actual tornado).
  • Splitting storm (or storm split)
  • Stability index
  • Stacked low
  • Steam devil
  • Storm chasing – Traveling with the intent to observe tornadoes and other severe weather.
  • Storm interaction
  • Storm merger
  • Storm relative environmental helicity (SREH) or storm relative helicity (SRH)
  • Storm shelter
  • Storm spotting – The observation of severe weather by individuals trained in weather and reporting. Spotters can be stationary or mobile.
  • Storm Data (SD) – A National Climatic Data Center (NCDC) publication beginning in 1959 detailing quality controlled tornado and other severe weather summaries as the official NOAA record of such events.
  • Storm Prediction Center (SPC) – The NWS national guidance center that issues tornado, severe thunderstorm (straight-line wind and hail), and wildfire forecasts.
  • Storm scale
  • Storm Track (magazine) (ST) – A science and hobby magazine on storm chasing published from 1977 to 2002.
  • Stovepipe tornado – (slang) Storm chaser slang for a large cylindrically shaped tornado resembling a stovepipe.
  • Straight-line wind
  • Streamline
  • Streamwise vorticity
  • Striations
  • Strong tornado – A tornado rated F2-F3, EF2-EF3, T4-T7, or at least as strong as F2, EF2, T4.
  • Subsidence
  • Subvortex – A smaller constituent vortex within a (multiple vortex) tornado.
  • Suction spot – Older term for a subvortex.
  • Supercell (sup)
  • Supercell composite parameter (SCP) – Model parameter calculated using Instability values, Helicity, and effective bulk wind difference.
  • Supertornado – (slang) A colloquial term used to refer to a tornado achieving the maximum of some measurement, such as a F5/EF5 tornado.
  • Surface weather analysis
  • Surface weather observation
  • Synoptic scale meteorology


Tornado rating classifications
Weak Strong Violent
  • Tail – (slang) A colloquial term for a tornado; most commonly used in the Southern U.S.
  • Tail cloud
  • Temperature
  • Terminal Doppler Weather Radar (TDWR) –
  • Thermal
  • Thermodynamics
  • Thunderstorm (tstm)
  • The Thunderstorm Project
  • Thunderstorm spectrum
  • Tilted updraft
  • Tornado (tor)
  • Tornado Alley – A colloquial term referring to regions where tornadoes are perceived as striking more frequently than other areas. It may also be referred to as a tornado belt, especially when describing smaller areas.
  • Tornado climatology – The study of geographical and temporal distribution of tornadoes and causes thereof.
  • Tornado couplet – A primary cyclonic tornado and secondary anticyclonic tornado pair.
  • Tornado Debris Project (TDP)
  • Tornado debris signature (TDS) – A more formal term for a debris ball.
  • Tornado emergency – Enhanced wording used by the U.S. National Weather Service in a tornado warning or severe weather statement when a large, intense tornado is expected to impact a highly populated area (traverse a large city or dense suburbs).
  • Tornado family – A series of tornadoes spawned by successive (low-level) mesocyclones of the same supercell thunderstorm in a process known as cyclic tornadogenesis. Multiple such supercells occurring on the same day in a common region results in a corridor outbreak of tornadoes.
  • Tornado fog
  • Tornado Force scale (TF scale)
  • Tornado Intercept Project (TIP)
  • Tornado outbreak
  • Tornado outbreak sequence
  • Tornado preparedness
  • The Tornado Project (TP) – A concerted research effort from the 1970s-1990s by Thomas P. Grazulis that compiled tornado information for risk assessment. TP published exhaustive accounts, tabulations, and analysis of all known significant tornadoes in the US from 1680 to 1995, which comprises one of three tornado databases.
  • Tornado pulse
  • Tornado rating – A subjective integer value assigned to a tornado differentiating its intensity (or path length or width), typically as a proxy inferred by damage analysis.
  • Tornado roar
  • Tornado scale
  • Tornado season
  • Tornado stages
  • Tornado Symposium
  • Tornado vortex signature (or tornadic vortex signature) (TVS)
  • Tornado watch (TOA or WT) – A forecast that atmospheric conditions within a designated area are favorable for significant tornado activity over the next 1–6 hours (colloquially referred to as red box).
  • Tornado warning (TOR) – A tornado is occurring or is imminent as one is sighted or is suggested by radar.
  • Tornadocyclone – The parent circulation of a tornado. This may refer to a low-level mesocyclone.
  • Tornadogenesis – The process leading to tornado formation.
  • Tornadolysis – The process leading to tornado decay and death.
  • TORRO (TORnado and storm Research Organisation)
  • TORRO scale – A tornado rating scale developed by Terence Meaden of TORRO classifying tornadoes in the UK from T0-T10 based on intensity.
  • TOTO (TOtable Tornado Observatory)
  • Transverse rolls
  • Trigger – (slang)
  • Tropical cyclone (TC)
  • Trough
  • Tube – (slang) A storm chaser term for a tornado.
  • Turbulence
  • Twister – (slang) A colloquial term for a tornado. Also, a major theatrical film about storm chasing released in 1996.
  • TWISTEX (Tactical Weather-Instrumented Sampling in/near Tornadoes EXperiment)





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