Glossary of tornado terms

National Weather Service Weather radar Mesocyclone

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) -


  • Jet max (or jet maximum) -
  • Jet streak -
  • Jet stream -










  • 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
  • Shear - Wind 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 1977-2002.
  • 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) -
  • 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 1680-1995, 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 nay 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) -





See also