Tornadogenesis via Squall Line and Supercell Interaction: The November 15, 1989, Huntsville, Alabama, Tornado

Plate 1. (Continued) Composite base-level radar reflectivity maps (NOWrad Composite Radar produced by WSI Corporation, Billerica, Massachusetts) obtained from regional NWS radars at (a) 2000 UTC, (b) 2100 UTC, (c) 2130 UTC, (d) 2200 UTC, (e) 2230 UTC, and (f) 2300 UTC. The radar reflectivity is contoured at 18, 30, 40, 45, 50, and 55 dBZ (VIP levels 1-6). is the U.S. government's official web portal to all federal, state and local government web resources and services.