Photos courtesy of Glen Romine, University of Illinois
Simulation of Landspouts using a Numerical Model:
Multiple landspouts (non-supercell tornadoes) develop in this simulation of a line of
non-rotating thunderstorms. The landspouts develop along a shear zone indicated by the contrasting
blue colors. The yellow columns represent the rotation of the landspouts.
Courtesy of Bruce Lee and Robert Wilhemson, University of Illinois/NCSA
Simulation of Airflow in a Landspout using a Numerical Model:
Airflow within landspouts (non-supercell tornadoes) can be seen in this simulation of
a line of non-rotating thunderstorms. Weightless tracer particles identify the air as either rising
(green) or sinking (red). Several of the landspouts merge during the animation.
Courtesy of Bruce Lee and Robert Wilhemson, University of Illinois/NCSA
Frequency of Tornadoes in the United States:
The sequence of images shows the likelihood of tornadoes for each calendar month in the contiguous
United States. The chart below shows the number of tornadoes (according to F-scale) observed in each calendar month
during a 70 year period. Note that the tornado occurrence shifts northward throughout the year with
the exception of a maximum along the Gulf coast during hurricane season.
Doppler Radar Reflectivity During the 3 May 1999 Tornado Outbreak:
Several supercell thunderstorms are evident on the radar reflectivity animation from 3 May
1999. Note the classic hook shaped echo of each supercell and the classic precipitation pattern
indicated by the color coding. The supercell that passed through Oklahoma City (OKC) and Moore
produced a tornado ranked as F-5 during part of its life cycle.
Doppler Radar Radial Velocity During the 3 May 1999 Tornado Outbreak:
Several tornado vortex signatures are visible on the radar radial velocity animation from 3 May
1999. The signatures indicate rotation in the thunderstorm and are identified by a coupling of red (outbound)
and green (inbound) colors.
