How to Read Tornado Tracks

Read the map in three layers

A dot marks the recorded start. A line connects that start to a recorded endpoint when one exists. Its color identifies the F or EF damage rating. Line thickness and dot size reflect recorded path width in yards on a fixed, compressed scale. Wider records appear wider, but symbols are enlarged for legibility and are not to-scale damage footprints. Widths of 3,000 yards or more share the largest symbol. Dashed lines and hollow, dashed dots indicate unavailable widths. Each line uses one recorded width throughout; it does not show changes in width along the path.

The path is an approximation

SPC’s single-track CSV is an event archive, not a detailed survey geometry. The connector between its endpoints can miss bends, discontinuities, or local variations. The listed path length is the archive’s reported value, not a measurement of the line drawn on the screen.

Dates and playback

The timeline follows the dates stored in the archive, predominantly Central Standard Time (CST, UTC−6), including summer dates. A record’s detail panel labels its time zone. Unrecognized time-zone codes are shown as unknown, without inventing a UTC conversion.

“Full year” displays all matching events in a calendar year. Choosing a date displays that date’s records. Playback advances through dates, revealing complete paths; it does not animate a tornado moving along an assumed route or duration.

State borders and missing positions

The state filter refers to the state where the tornado touched down. A single track can continue across other states. Alaska and Hawaii appear as map insets. Records outside the map projection—including Puerto Rico and the U.S. Virgin Islands—or without valid start coordinates remain available in the explorer and are counted in the map’s coverage note.

Source: SPC database field specification.