Current Members

Paul Markowski became interested in meteorology as a result of the 31 May 1985 tornado outbreak in western Pennsylvania.  He received a B.S. in Meteorology from Penn State University, and an M.S. and Ph.D. in Meteorology from the University of Oklahoma.  He has been on the faculty in the Department of Meteorology and Atmospheric Science at Penn State since 2001.  He co-organized the Second Verification of the Origins of Rotation in Tornadoes Experiment (VORTEX2), served as the Chief Editor of the American Meteorological Society’s Journal of Weather and Forecasting from 2012–2017, serves on the President’s Advisory Committee on University Relations for the University Corporation for Atmospheric Research, and is a fellow of the American Meteorological Society.  At Penn State, he is the Associate Head of the Graduate Program in Meteorology & Atmospheric Science, serves on the University Graduate Council, and is the faculty partner for the Men’s Golf Team.  He enjoys spending time with his family, especially playing sports with his two sons.  In a past life he played a lot of baseball, and now plays a lot of golf.

Paul Markowski’s CV         Google Scholar        ORCID


Branden Katona joined the group in August, 2014, after received a B.S. in meteorology from the University of Oklahoma.  Branden received an M.S. in meteorology in the spring of 2016, and is now working on a Ph.D.  His M.S. work (M.S. thesis: “Assessing the Influence of Topography on Convective Storm Environments Using High-resolution Operational Model Output”) investigated topographically forced variations in thunderstorm environments in the eastern U.S.  His Ph.D. work uses carefully controlled computer simulations to study the ways in which topography affects the development of intense vortices within supercell thunderstorms.  In his spare time, Branden studies beer.




Shawn Murdzek is a Ph.D. student working with Profs. Richardson and Markowski on the predictability of supercell storms, specifically, on the subject of whether there is less sensitivity to microphysical processes in certain types of storm environments.  Shawn is a National Science Foundation Graduate Fellow.  Before beginning his Ph.D., he received his B.S. and M.S. degrees at Penn State as an IUG (Integrated Undergraduate-Graduate) student.  His M.S. work involved dual-Doppler wind syntheses of the 26 May 2010 weakly tornadic supercell storm intercepted by VORTEX2.



Elissa Bartos is an M.S. student who joined the group in August 2018, after earning a B.S. in Meteorology from Texas A&M University in May 2018 (and a B.A. in History from the University of Texas at Austin in May 2009). Working with Profs. Markowski and Richardson, Elissa is studying the thermodynamic and buoyancy fields within supercell storms using observations above the surface from pseudo-Lagrangian balloon drifters. Outside of meteorology, Elissa is an active target archer who shoots an Olympic recurve style bow.  She could probably shoot down her own pseudo-Lagrangian drifters, but this would jeopardize her thesis research.



Dylan Steinkruger is an M.S. student who joined the group in August, 2018.  His work focuses on studying tornadogenesis in nonclassical tornadic storms using computer simulations and machine learning techniques. Previously, he received a B.S. in meteorology at the University of Nebraska-Lincoln. Outside of meteorology, Dylan also enjoys sprint car racing and football officiating.







Aaron Wang is a Ph.D. student investigating the influence of the underlying surface on a supercell. He received his B.S. in both Atmospheric Sciences and Mechanical Engineering in 2014, and an M.S. in Atmospheric Sciences in 2016 at National Taiwan University. He likes fluid dynamics and vortex dynamics.  He served his substitute military service in the Weather Forecast Center of Central Weather Bureau in Taiwan.  Aaron also likes studying the Bible and playing fingerstyle guitar.





Giovanni Jiménez-Sánchez received his Ph.D. in December, 2018 (Dissertation: “The Orinoco Low-Level Jet”).  He is a Major in the Colombian Air Force, where he used to be the Director of Meteorology before coming to PSU.  He holds a bachelor’s degree in aviation business administration (Escuela Militar de Aviación “Marco Fidel Suárez”) and an M.S. in meteorology (Universidad Nacional de Colombia).  The Orinoco low-level jet was a particularly interesting dynamics problem in that neither the Holton nor Blackadar mechanisms could explain the phenomenon.






Valerian Jewtoukoff (“Val”) was a postdoctoral scholar in the group from May, 2016–December, 2017, after completing a Ph.D. in meteorology and M.S. in atmospheric and oceanic dynamics at the Université Pierre et Marie Curie in Paris.  His Ph.D. and M.S. research was on balloon-borne observations and simulations of gravity waves, looking at their origins, propagation, and impacts.  Prior to focusing on meteorology, Val received two B.S. degrees, one in physics and one in geophysics, from the Université Paris Diderot in Paris.  Val’s work at PSU used numerical simulations to investigate how “surges” of cold air can disrupt or intensify tornadoes.  Val is an avid skier.





Michael Colbert received his M.S. in 2017 (M.S. Thesis: “Exploring the Sensitivity of Convective Storm Characteristics and Dynamics to Grid Spacing in Convection-Allowing North American Mesoscale Forecast System Simulations”).  Michael’s work examined the ability of the North American Model (NAM) 4-km and 1.33-km nests to realistically simulate severe thunderstorm behavior and dynamics.  He currently is a research associate working under the supervision of Prof. Dave Stensrud, where he is investigating the ability of the high-resolution NAM to accurately represent the dynamical processes associated with convection initiation.




Abdullah Kahraman was a visiting scholar from Turkey from August 2013 to August 2014.  He received his Ph.D. in Meteorological Engineering from Istanbul Technical University in the fall of 2016.  He has studied Turkish tornadoes and severe hailstorms extensively.  He now is on the faculty of Ondokuz Mayıs University in Samsun, Turkey.






Jim Marquis was a graduate student in Prof. Yvette Richardson’s group, and from late 2010 through late 2014, he was a postdoctoral scholar who collaborated with both Profs. Richardson and Markowski.  Jim blazed a trail on an extremely difficult problem with working as a post-doc: ensemble Kalman filter assimilation of Doppler On Wheels and mobile mesonet data obtained during the VORTEX2 intercept of the Goshen County (Wyoming) tornadic supercell on 5 June 2009.  Jim now resides in Boulder, Colorado, and is a scientist at the Center for Severe Weather Research.





Chris Nowotarski received his M.S. in 2010 (M.S. Thesis: “The Characteristics of Numerically Simulated Supercell Storms Situated over Statically Stable Boundary Layers”) and Ph.D. in 2013 (Dissertation: “Simulating Supercell Thunderstorms in a Convective Boundary Layer: Effects on Storm and Boundary Layer Properties”).  He has been on the faculty of the Department of Atmospheric Sciences at Texas A&M University since January, 2014.  His website can be reached by clicking here.







Tim Hatlee was co-advised by Prof. Yvette Richardson and received his M.S. in 2012 (M.S. Thesis: “The Pretornadic and Tornadogenesis Phases of the 12 May 2010 Supercell of Clinton, Oklahoma, Intercepted by VORTEX2”).  Tim currently works in New York City for the Skills Lab as a Skills Fellow ( Quoting their website, “The Skills Fellowship Program is comprised of innovative teachers, known as Skills Fellows, who desire to enhance their practices by making 21st century skills development more prominent in their instruction, assessment and feedback practices. Each Skills Fellow receives support from an instructional Skills Coach in order to more effectively integrate 21st century skills into their instructional practice.”




Andrew Oberthaler received his M.S. in 2011 (M.S. Thesis: “The Effect of Cloud Shading on Squall Lines: A Numerical Simulation Study”).  After departing Penn State, he joined Ubimet, a private weather forecasting firm in Vienna, Austria, where he was responsible for weather forecasting for Formula 1 auto races worldwide.  On the side, he played professional baseball for the Vienna Wanderers and won two Austrian national titles.  No doubt, his skills were honed while playing on the meteorology IM softball team!  Andrew now resides in Berlin, Germany, where he now works for TD Reply, a marketing company, where he uses his expertise in data mining and machine-learning.  He is still playing baseball, now with the Berlin Flamingos.




Mario Majcen hails from Croatia and, after completing his M.S. at the University of Utah, joined the group in 2005.  He received his Ph.D. in 2009 (Dissertation: “A Conceptual Model of Nontornadic Supercells”).  Shortly thereafter, he joined the faculty at the California University of Pennsylvania, where he has been ever since.  While at Penn State, he was well-known for his superior skills in the popular game Taboo.





Jeff Frame was admitted into the group in 2001 despite being a University of Michigan graduate.  He (along with Christina Hannon) became the first graduate of the Markowski Research Group when he received his M.S. in 2003 (M.S. Thesis: “The Interaction of Simulated Squall Lines with Idealized Terrain”).  Jeff remained at Penn State for his Ph.D., which was conferred in 2008 (Dissertation: “The Dynamical Influences of Cloud Shading on Simulated Supercell Thunderstorms”).  He has been a Clinical Assistant Professor in the Department of Atmospheric Sciences at the University of Illinois since 2010.  Click here to get to his webpage.




Richard James began his Penn State career in Prof. Mike Fritsch’s group.  After a brief hiatus from State College, he returned in 2008 to complete his Ph.D. (Dissertation: “A Numerical Investigation of the Effects of Dry Air Aloft on Deep Convection”).  He currently resides in Athens, Georgia, and works for Prescient Weather Ltd, a small company based in State College that “provides information and strategies to manage weather and climate risk.”







Zack Byko was co-advised by Prof. Yvette Richardson and received his B.S. and M.S. (M.S. Thesis: “Examining Descending Reflectivity Cores Using High-Resolution Radar Data and a Numerical Simulation”) in 2007 through PSU’s Integrated Undergraduate–Graduate (IUG) program.  Zack is a Senior Strategic Sourcing Manager for Mars Chocolate.





Jeremy Ross overlapped at Penn State with Paul Markowski when both were undergraduates back in the 1990s.  Jeremy received his B.S., M.S., and Ph.D. from Penn State, with most of his M.S. work and Ph.D. work being completed while working in Prof. Mike Fritsch’s group.  After Mike retired, Jeremy finished his Ph.D. within the Markowski Research Group in 2005 (Dissertation: “Reexamining Analog Forecasting Using NCEP/NCAR Reanalyses”).  In the final days of his Ph.D. work, Jeremy and Paul won the IM golf championship as a two-person team.  Jeremy now resides in nearby Zion, Pennsylvania, and works for Prescient Weather Ltd in State College.






Chris Shabbott received his M.S. in 2003 (M.S. Thesis: “Surface Thermodynamic Observations within the Forward-Flank Downdrafts of Tornadic and Nontornadic Supercells”) after a strong performance as a Penn State undergraduate (B.S., 2001).  Chris now resides near Stamford, Connecticut, and works for Castleton Commodities International LLC (formerly Louis Dreyfus Highbridge Energy).





John Stonitsch was one of two graduate students in the group who analyzed data from the International H2O Project (M.S. Thesis: “The Fine-Scale Structure and Evolution of Boundary Layer Wind and Thermodynamic Fields along a Front Observed during IHOP”).  John’s M.S. was earned in 2005, and before entering the graduate program, he received his B.S. in meteorology from Penn State in 2003.   John has worked in the energy sector in the Houston area as an extremely skillful weather forecaster since leaving the group in 2005.  I do not have a current photo of him, but found this old Blue Band photo of him that still lives on the Internet.  Let’s see how long it takes John to find this and submit a new one!





Christina Henderson (née Hannon) joined the group in August, 2001, after earning her B.S. in meteorology from the University of Oklahoma.  She (along with Jeff Frame) became the first graduate of the Markowski Research Group when she received her M.S. in 2003 (M.S. Thesis: “An Investigation of Convection Initiation ‘Failure’ on 12 June 2002 Using Mobile Doppler Radars”).  Her M.S. research used overdetermined dual-Doppler radar data obtained during an International H2O Project deployment in northwestern Oklahoma to investigate the failure of towering cumulus clouds to develop into thunderstorms.  She has worked in the National Weather Service in the western Great Plains region since leaving Penn State.  She now resides in Stratton, Nebraska.