Doppler Radar Data Related to F-Scale for the May 3rd Oklahoma City Tornado

.A unique opportunity for analysis arises from the occurrence of an F5 tornado in close proximity to two WSR-88D radars (one operational radar and one test radar). The high-resolution radar data can be compared to detailed F-Scale evaluations associated with a large-scale survey effort by the Norman weather community.

The Oklahoma City supercell was classic in radar appearance and had been in existence for some time before the Oklahoma City tornado formed. The F5 tornado was the 6th in a series of 11 tornadoes produced by the storm. At F5 tornado development time, the hook echo possessed only moderate reflectivities and weak to moderate tornado-related shears. As the tornado became progressively stronger, reflectivity and shear in the knob of the hook echo increased. During the first interval when the tornado was violent (F4/F5 damage), reflectivity and shear were a relative maximum. As the tornado weakened to strong strength (F2/F3 damage), reflectivity and shear in the knob of the hook decreased. Entering the Oklahoma City metropolitan area, the tornado strengthened again (F4/F5 damage) with dramatically higher reflectivity in the knob of the hook and increased shear. The highest knob reflecitivites occurred as the tornado moved across the metropolitan area. It is suspected that much of the reflectivity increase in the knob of the hook came from the tremendously large amounts of lofted debris that were generated.

Analyses are being performed of reflectivity and radial velocity data as they relate to tornado damage/intensity. Time/height profiles are being generated. Special emphasis is being given to the reflectivity in the knob of the hook echo as an indicator of the magnitude of debris lofted by the tornado