A History of Severe-Storm-Intercept Field Programs

Abstract

Efforts to study severe convective storms and tornadoes by intercepting them either on the ground or on airborne platforms are highlighted. Airborne sorties into or near waterspouts in the Florida Keys with instruments were made in the late 1960s and the 1970s. The main goals of the first organized ground-based severe storm intercept field programs in the 1970s at the National Severe Storms Laboratory and at the University of Oklahoma were to verify severe weather signatures detected by a remote Doppler radar, to identify cloud features that could aid storm spotters, and to estimate wind speeds in tornadoes based on the photogrammetric analysis of tornado debris movies. Instruments were subsequently developed that could be carried along on intercept vehicles to measure in situ electric field change, thermodynamic variables, and wind, near the ground and aloft. Beginning in the late 1980s, portable and mobile Doppler radars were developed that could be used to make estimates of the maximum wind speeds in tornadoes and to map out the wind field in tornadoes. Airborne radar systems developed and flown in hurricanes in the 1980s were further refined and used in the 1990s to map out the wind field in severe convective storms. All these instruments were used in 1994 and 1995 in a large, coordinated, storm-intercept field program. Other efforts over the years have focused on collecting hail and on recording the sound from tornadoes. Some of the most important scientific results are summarized. Among the most significant are the identification of the visual architecture of tornadic supercells, the discovery of different modes of tornado formation and other types of vortices, and the verification of extremely high wind speeds in tornadoes previously only inferred from damage.