Dictionary
Tornado terminology A to Z
Every tornado term you've heard, plus dozens you haven't. From "anticyclonic" to "wedge tornado" — the definitive alphabetical reference.
A
- Anticyclonic — rotating clockwise (opposite of typical Northern Hemisphere tornadoes).
- Anvil — flat spreading top of mature thunderstorm.
- Anvil crawler — lightning discharge along the anvil underside.
- ASOS — Automated Surface Observing System. Airport weather stations.
- Atmosphere — the layer of gas surrounding Earth.
B
- Backing wind — wind that turns counterclockwise with height.
- Barometer — instrument measuring pressure.
- Beaver tail — inflow band extending from wall cloud toward rain.
- Book-end vortex — rotation at the ends of a bow echo.
- Bow echo — bow-shaped line of thunderstorms on radar.
- Bulk shear — magnitude of wind change with height.
C
- CAPE — Convective Available Potential Energy. Measure of instability.
- Cap — warm layer aloft inhibiting convection.
- Cirrus — high wispy ice cloud.
- CIN — Convective Inhibition. Energy needed to overcome cap.
- Cirrostratus — high thin cloud sheet.
- Clear slot — RFD-driven clearing on the west/south side of a mesocyclone.
- Convection — vertical motion of air.
- Cumulonimbus — thunderstorm cloud.
- Cyclonic — rotating counterclockwise (Northern Hemisphere typical).
D
- Debris cloud — cloud of ground material lifted by a tornado.
- Debris signature (TDS) — radar signature of tornado-lofted debris.
- Derecho — long-lived widespread damaging wind event.
- Dewpoint — temperature at which air is saturated.
- Doppler — radar measuring velocity via frequency shift.
- Downburst — concentrated downdraft producing damaging surface winds.
- Downdraft — descending air current in a storm.
- Dryline — boundary between moist and dry air.
- Dust devil — small vortex from surface heating (not a tornado).
E
- EF Scale — Enhanced Fujita Scale. Wind damage rating from EF0 to EF5.
- Elevated storm — storm where updraft is above the surface layer.
- Ensemble — multiple forecast runs to quantify uncertainty.
- Enhanced Skywarn — advanced spotter training.
F
- Fair-weather waterspout — non-supercell waterspout.
- Fine line — radar signature of gust front.
- Flash flood — sudden intense localized flooding.
- Flanking line — line of towering cumulus behind a supercell.
- Fujita scale — original (F0-F5) tornado rating, replaced by EF.
- Funnel cloud — rotating condensation cloud NOT touching ground.
G
- Gate-to-gate shear — velocity difference between adjacent radar gates.
- Gust front — leading edge of storm outflow.
- Gustnado — non-tornado spin-up along gust front.
- GFS — Global Forecast System model.
- GEFS — Global Ensemble Forecast System.
H
- Hail — precipitation of ice pellets.
- Hail core — center of highest hail concentration.
- High Precipitation (HP) supercell — supercell with heavy rain wrapping around updraft.
- Hodograph — plot of wind vector with height.
- Hook echo — radar signature of mesocyclone.
- HRRR — High-Resolution Rapid Refresh model.
I
- Impact-Based Warning — tiered warning system (CONSIDERABLE, CATASTROPHIC).
- Inflow — air flowing into a storm.
- Inflow tail — cloud band pointing into storm inflow.
- Inversion — layer where temperature increases with height.
J-K
- Jet streak — localized zone of maximum jet stream wind.
- Kelvin-Helmholtz waves — breaking wave cloud pattern.
L
- Landspout — non-supercell tornado.
- LCL — Lifted Condensation Level. Height at which parcel becomes saturated.
- Left-mover — supercell with anticyclonic rotation moving left of mean wind.
- Lightning — atmospheric electrical discharge.
- Low Precipitation (LP) supercell — supercell with little precipitation.
M
- Mammatus — pouches hanging from cumulonimbus underside.
- Mesocyclone — rotating updraft within supercell.
- Mesoscale Convective System (MCS) — organized cluster of storms.
- Microburst — small-scale intense downburst.
- Multi-vortex tornado — tornado containing multiple subvortices.
- MUCAPE — Most Unstable CAPE.
N
- NEXRAD — Next Generation Radar. NWS national radar network.
- Non-supercell tornado — tornado formed by mechanism other than supercell mesocyclone.
- Nose — leading edge of dryline.
O
- Occlusion — mesocyclone wrapped by cool RFD.
- Outflow — cold air spreading from storm.
- Overshooting top — dome briefly above anvil.
P
- PDS — Particularly Dangerous Situation. Tag on SPC outlooks.
- PIREP — pilot report.
- Pulse severe storm — single-cell storm producing brief severe weather.
- PyroCB — pyrocumulonimbus. Fire-generated thunderstorm.
Q-R
- QLCS — Quasi-Linear Convective System. Squall line.
- Rear-Flank Downdraft (RFD) — downdraft behind updraft.
- Rear-Inflow Jet — upper-level winds punching into back of bow.
- Right-mover — supercell moving right of mean wind.
- Rope out — tornado dissipating into thin rope-like funnel.
S
- SBCAPE — Surface-Based CAPE.
- Severe thunderstorm — storm with 1"+ hail, 58+ mph winds, or tornado.
- Shear — change in wind with height or distance.
- Skywarn — NWS storm spotter network.
- Slight risk — SPC lowest severe risk category.
- SPC — Storm Prediction Center.
- Squall line — line of thunderstorms.
- Storm relative helicity (SRH) — measure of streamwise rotation.
- Subvortex — smaller vortex within multi-vortex tornado.
- Suction vortex — synonym for subvortex.
- Supercell — thunderstorm with persistent rotating updraft.
T
- TDS — Tornado Debris Signature.
- Tornado — rotating column of air in contact with ground and cloud.
- Tornado Emergency — highest impact-based warning tag.
- Tornado warning — imminent tornado threat.
- Tornado watch — conditions favorable for tornadoes.
- Training storms — successive storms over same area.
- Tropopause — boundary between troposphere and stratosphere.
- TVS — Tornado Vortex Signature.
U
- Updraft — rising air current in a storm.
- Undulatus asperitas — wavy chaotic cloud base.
V
- Veering wind — wind that turns clockwise with height (favors tornadoes).
- Virga — precipitation evaporating before ground.
- VORTEX — Verification of the Origins of Rotation in Tornadoes Experiment.
- Vorticity — measure of rotation in fluid.
W
- Wall cloud — lowered rotating cloud below storm base.
- Warning — imminent hazardous weather.
- Watch — conditions favorable for hazardous weather.
- Waterspout — tornado over water.
- Wedge tornado — tornado wider than it is tall.
- WEA — Wireless Emergency Alert.
- WFO — Weather Forecast Office.
- Whirlwind — generic term for any rotating column.
X-Y-Z
- X-band radar — high-frequency mobile radar used by researchers.
- Zonal flow — largely west-to-east jet stream flow.
- Z-R relationship — reflectivity to rainfall rate conversion.