Characteristics of Supercellular Satellite Tornadoes

Over the past two decades, a brief mention in a few literature articles, the author's direct observations, and abundant imagery from other storm observers, have documented a class of an accessory tornadic vortex known as the satellite tornado (ST). The ST accompanies a much longer-lived, typically larger and higher-damage-rated main tornado (MT), around which it often orbits within the periphery of the same mesocyclone. Despite that close association, the ST is not a subvortex of the same tornadic circulation as the MT. Instead, visual and mobile-radar observations (each presented herein) strongly indicate that the ST and MT are separate and distinct from one another, except for a few cases where the MT eventually absorbs the ST. A list of 39 STs has been compiled so far, likely to grow as more historic information and newly observed events are documented. Many STs are not found in Storm Data, or are noted only in remarks; therefore, this is an independent dataset. The data include all available date, time, location, rating and path information for both the ST and MT in each event. Preliminary analyses show a strong preference for STs to occur around very wide, long-tracked, strong or violent (EF3–EF5) MTs with mean path lengths >35 km and widths >1300 m. Historic case descriptions, archetypical examples and geographic distributions also will be presented. ST implications for tornado climatology, damage surveys and spotter safety will be discussed.