Modeling Group

Atmospheric Sciences Department & NCSA
University of Illinois at Urbana-Champaign


The research presented here is sponsored by the National Science Foundation.


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26th Conference on Severe Local Storms

The AMS 26th Conference on Severe Local Storms was held in Nashville, TN from November 5-8, 2012. Attending from the Univ. Illinois Convective Modeling Group were (left-to-right in photo) M.S. graduate students Kevin Van Leer and Samantha Chiu, research assistant Ann Syrowski (M.S. May 2012), and (not pictured) PI's Robert Wilhelmson and Brian Jewett. Kevin, Samantha, and Ann had oral presentations at the meeting.

Storm Interaction

Ann Syrowski presented the findings of her M.S. thesis, "An assessment of internal and external forcings in supercell interactions and their impact on storm morphology." The structure and evolution similarities and differences among a single-storm control case and 51 two-storm simulations were discussed, and intensification mechanisms were identified. The dynamic connections between (and timings of) a key sequence of events were identified for the control and selected strong and weak 2-storm cases: (1) wet microbursts reached the surface behind the forward flank downdraft (FFD), (2) shallow rotation centers formed along and moved down the FFD, and (3) subsequent near-surface rotation intensification episodes (mesocyclonesis) occurred. Ann is preparing a manuscript for submission to Monthly Weather Review.

Long-Track Tornadoes: The April 27, 2011 Outbreak

Samantha Chiu presented the findings of her ongoing master's work on long-track tornadoes and simulations of the 27 April 2011 tornado outbreak. Over 300 tornadoes struck the southeast U.S. in the outbreak*, including the devastating Tuscaloosa-Birmingham EF-4 tornado with a damage path 80 miles long and up to 1.5 miles wide (radar sequence at left, ©NCAR). Chiu's real-data simulations of the event, with high resolution (0.3-km grid spacing) simulations of the outbreak, feature two long-lived supercell storms including one very near the track and timing of the Birmingham storm. Samantha is using these simulations and complimentary idealized runs with the Weather Research and Forecasting (WRF) model to assess the environment along the path of the storms and understand the stability and shear conditions under which such a long-track tornado could occur.
*See also AMS presentation by K. Knupp

Storm Mergers and Rapid Intensification in the 2011 Joplin Tornadic Storm

Kevin Van Leer's talk was on "Rapid intensification mechanisms including the role of storm mergers in the 22 May 2011 Joplin, MO tornadic storm." The presentation first addressed the unusual and somewhat surprising severity and rapid development of the storm and the environmental conditions in place at the time of the devastating tornado in Joplin. Mechanisms which could contribute to this intensification were discussed, including storm mergers that occurred before the tornado. High-resolution (0.3 km) modeling of this case also produced mergers, and animations of simulated mergers, the structure and evolution of precipitation, and low level rotation in the simulation were used to investigate the relationship between boundaries, cell movement, descending reflectivity cores and near-surface vorticity generation. Kevin is continuing this work toward his M.S. degree. His presentation won a student award at the SLS meeting, and his preliminary findings are the subject of a Bulletin of the American Meteorology Society meeting note (accepted; in February BAMS).