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Thanks for stopping by. I am an atmospheric scientist with the Cooperative Institute for Meteorological Satellite Studies (CIMSS) / Space Science and Engineering Center (SSEC) at the University of Wisconsin. This site is primarily a collection of media highlighting my research on supercell thunderstorms and tornadoes. The goal of this research is to understand the internal workings of supercell thunderstorms well enough to significantly improve our forecasting of their behavior. What makes this work significant is the use of supercomputing resources to produce simulations of supercells where data is saved with extremely high spatial and temporal resolution, and the use of visualization techniques (such as volume rendering and trajectory clouds) to produce video that exposes the highly variable flow features that occur throughout the life of the simulated storms. Some of these simulations contain long lived tornadoes producing near-surface winds exceeding 300 mph. Thus far this effort has been focused primarily on the 24 May 2011 El Reno event, initializing the CM1 model with a RUC sounding representative of the actual environment adjacent to the storm that produced the observed EF5 tornado.
Selected presentations are found below in reverse chronological order. For other presentations I have given since 2014, please see my youtube channel, which contains all of the video material I have created, which is a mix of scientific and general public presentations.
Under the Education tab you can find videos and other information specifically designed for a general audience. Much of this material was not produced by myself, but includes interviews and video of storm simulations.
AMS Conference on Severe Local Storms 2022 talk, “A vortex-relative perspective on tornadogenesis in a large-eddy supercell simulation containing a violent long-track tornado”
New article: Bannigan, N., L. Orf, and E. Savory, 2022: Tracking the Centre of Asymmetric Vortices Using Wind Velocity Vector Data Fields. Bound.-Layer Meteorol., https://doi.org/10.1007/s10546-022-00739-0. Publisher’s shareable PDF of paper.
Hannah Osborne (Newsweek magazine): “Peering Into the Deadliest, Most Destructive Tornadoes with Supercomputers”
New page dedicated to AACP research, contains recent talk:
“Hydraulic jump dynamics associated with Above Anvil Cirrus Plumes”
Seminar, UW-Madison, Department of Atmospheric and Oceanic Sciences
“CFD Simulation of Downbursts” presented virtually at THUNDERR / Genoa. Supplemental materials are found by clicking here.
New article out in Science! “Hydraulic jump dynamics above supercell thunderstorms”
I produced a video for the Computer Museum of America about supercomputers and cloud modeling:
Q&A session on youtube
New paper published describing recent research conducted on the NSF-sponsored Frontera supercomputer: Orf, L., 2021: Modeling the World’s Most Violent Thunderstorms. Computing in Science Engineering, 23, 14–24.
AMS On The Air interview (from the 100th Annual AMS meeting in Boston, 1/2020). I am one of several people interviewed by Dakota Smith 100th AMS Annual Meeting. I talk primarily about my recent high resolution supercell simulations and the problems we’re trying to solve in understanding tornadoes and supercells.
I was a guest on the Chaser Chat podcast with Gabriel Harber:
The Texas Advanced Computing Center (TACC) has written an article about some of my latest research:
Presentation at the Severe Local Storms Symposium of the 100th annual AMS meeting in Boston: “A 10-m resolution quarter trillion gridpoint tornadic supercell simulation”
Also presented at AMS:
Three new publications out:
Li, S., S. Jaroszynski, S. Pearse, L. Orf, and J. Clyne, 2019: VAPOR: A Visualization Package Tailored to Analyze Simulation Data in Earth System Science. Atmosphere , 10, 488. https://doi.org/10.3390/atmos10090488
Orf, L., 2019: A Violently Tornadic Supercell Thunderstorm Simulation Spanning a Quarter-Trillion Grid Volumes: Computational Challenges, I/O Framework, and Visualizations of Tornadogenesis. Atmosphere , 10, 578. https://doi.org/10.3390/atmos10100578
“Using supercomputers to simulate super tornadoes” produced by Futurum, a group that produces materials for secondary school students and educators. The website and brochure feature my research on simulating tornadoes and supercell thunderstorms using supercomputers.
“Ultra-high resolution supercell simulations visualized with VAPOR v3” – 30 minute presentation given at the 2019 NCAR International Computing for the Atmospheric Sciences Symposium in Stresa, Italy on 10 September 2019. The talk features new visualizations of a quarter-trillion gridpoint simulation (10 meter grid spacing) of a tornadic supercell thunderstorm.
I’m briefly featured in the first episode of National Geographic’s “Witness To Disaster” series.
July 13, 2019:
Hank Schyma “Pecos Hank” second interview video, comparing simulation data with observations and chatting about a developing new theory of tornadogenesis.
June 3, 2019:
“Petascale supercell thunderstorm simulations and a new hypothesis for tornado formation and maintenance” presented at the 2019 Joint Congress of the Canadian Society for Mechanical Engineering and Computational Fluid Dynamics Society of Canada at Western University, London, ON.
April 13, 2019:
“Tornadoes and Technology: Simulating and Analyzing The World’s Most Devastating Storms” (45 minutes) presented at the 5th annual Dark Skies Severe Weather Seminar at Madison College.
This video is dedicated to Chippewa Falls, WI: home of Cray Supercomputing and Leinenkugel’s Beer. 🙂
April 11, 2019:
“Supercells and Supercomputers: Simulating The Most Devastating Tornadoes” 1 hr seminar presented at Purdue University, Department of Earth, Atmosphere, and Planetary Science.
March 28, 2019:
“Tornadoes and Technology: Simulating and Analyzing the World’s Most Devastating Storms” presented by Leigh Orf at the 23rd Annual National Weather Association Severe Storms and Doppler Radar Conference.
October 22, 2018:
“The Role of the Streamwise Vorticity Current in Tornado Genesis and Maintenance” presented by Leigh Orf at the 29th Conference on Severe Local Storms in Stowe, VT on October 22, 2018.
November 22, 2017: Storm chaser extraordinaire Hank Schyma (“Pecos Hank”) produced a documentary where we discuss my latest research and compare some of his own observations of supercells and tornadoes to some of my own simulations:
November 1, 2017: WIRED article about my research team, and a narrated video with recent simulations:
May 3, 2017: PBS Newshour segment:
April 14, 2017: PBS Newshour article/q&a session with Julia Griffin
March 26, 2017 (air date): I was a guest on Wx Geeks, hosted by Dr. Marshall Shepherd, on The Weather Channel.
June 13, 2016 Blue Waters Symposium presentation “Unlocking the mysteries of the most violent tornadoes and the storms that produce them” that discusses our first article (referenced below) shortly after it was published online.
The first major publication on this work can be found in the January 2017 issue of BAMS:
Orf, L., R. Wilhelmson, B. Lee, C. Finley, and A. Houston, 2017: Evolution of a Long-Track Violent Tornado within a Simulated Supercell. Bull. Am. Meteorol. Soc., 98, 45–68. http://dx.doi.org/10.1175/BAMS-D-15-00073.1.