Walker Ashley

Research Emphases

• Mesoscale meteorology
• Disaster science
• Climate change

Specific Research Endeavors

I am an atmospheric scientist and disaster geographer with an interest in extreme weather and societal impacts. My research team uses an interdisciplinary approach, employing techniques that span the social and physical sciences—from qualitative, survey-based research, to remote sensing and GIS, to the use of computer algorithms on remotely sensed data and numerical model output generated via high-performance computing. My scholarship characterizes the spatiotemporal distributions of hazardous weather phenomena, their societal impacts and how, ultimately, disasters will change in the 21st century. The goal is to supply government and industry stakeholders, policymakers and the public with the information necessary to mitigate disasters and build resilience in the face of rapid environmental and societal change.

Frequently Taught Classes

• EAE 105: Weather, Climate and You
• EAE 306: Severe and Hazardous Weather
• EAE 406/506: Science of Disaster
• EAE 498/600: GIS Applications in Meteorology and Climatology
• MET 360: Radar Meteorology
• MET 444/544: Mesoscale Meteorology

Representative Publications

• Ashley, W. S., A. Zeeb, A. Haberlie, V. Gensini and A. Michaelis, 2025: The future of snowstorms in central and eastern North America. International Journal of Climatology
• Kaminski, K., W. S. Ashley, A. M. Haberlie and V. A. Gensini, 2025: Future derecho potential in the United States. Journal of Climate.
• Gensini, V. A., W. S. Ashley, A. C. Michaelis, A. M. Haberlie, J. Goodin and B. C. Wallace, 2024: Hailstone size dichotomy in a warming climate. npj Climate and Atmospheric Science.
• Haberlie, A. M., B. Wallace, W. S. Ashley, V. Gensini and A. Michaelis, 2024: Mesoscale convective system activity in the United States under intermediate and extreme climate change scenarios. Climatic Change.
• Strader, S. M., V. A. Gensini, W. S. Ashley and A. N. Wagner, 2024: Changes in tornado risk and societal vulnerability leading to greater tornado impact potential. npj Nat. Hazards.
• Zeeb, A. W., W. S. Ashley, A. M. Haberlie, V. A. Gensini and A. C. Michaelis, 2024: Supercell precipitation contribution to the United States hydroclimate. International Journal of Climatology.
• Ashley, W. S., A. M. Haberlie and V. A. Gensini, 2022: The future of supercells in the United States. Bulletin of the American Meteorological Society.

• Strader, S. M, W. S. Ashley, A. Haberlie and K. Kaminski, 2022. Revisiting U.S. nocturnal tornado vulnerability and its influence on tornado impacts. Weather, Climate and Society.
• Haberlie, A. M., W. S. Ashley, C. M. Battisto and V. A. Gensini, 2022: Thunderstorm activity under intermediate and extreme climate change scenarios. Geophysical Research Letters, 49, e2022GL098779.
• Gensini, V., A. Haberlie and W. S. Ashley, 2022: Convection-permitting simulations of historical and possible future climate over the contiguous United States. Climate Dynamics. doi.org/10.1007/s00382-022-06306-0.
• Stevens, B. R. and W. S. Ashley, 2022: Fatal weather-related carbon monoxide poisonings in the United States. Weather, Climate and Society, 14, 373-386.
• Gensini, V. A., C. Converse, W. S. Ashley and M. Taszarek, 2021: Machine learning classification of significant tornadoes and hail in the United States using ERA5 proximity soundings. Weather and Forecasting, 26, 2143–2160.
• Eboh, H., C. Gallaher, T. Pingel and W. S. Ashley, 2021: Risk perception in small island developing states: A case study in the Commonwealth of Dominica. Natural Hazards, 105, 889–914.
• Haberlie, A. M., W. S. Ashley and M. Karpinski, 2021: Mean storms: Composites of radar reflectivity images during two decades of severe thunderstorm events. International Journal of Climatology, 41, E1738-E1756.
• Ashley, W. S., A. M. Haberlie and V. Gensini, 2020: Reduced frequency and size of late twenty-first-century snowstorms over North America. Nature Climate Change.
• Ashley, W. S., A. M. Haberlie and J. Strohm, 2019: A climatology of quasi-linear convective systems and their hazards in the United States. Weather and Forecasting, 34, 1605-1631.
• Haberlie, A. M. and W. S. Ashley, 2019: A radar-based climatology of mesoscale convective systems in the United States. Journal of Climate, 19, 1591-1605.
• Haberlie, A. M. and W. S. Ashley, 2018: Climatological representation of mesoscale convective systems in a dynamically downscaled climate simulation. International Journal of Climatology, 39, 1144-1153.
• Strader, S. M. and W. S. Ashley, 2018: Fine-scale assessment of mobile home tornado vulnerability in the Central and Southeast U.S. Weather, Climate and Society, 10, 797–812
• Strader, S. M., W. S. Ashley, T. J. Pingel and A. J. Krmenec, 2017: Projected 21^st century changes in tornado exposure, risk and disaster potential. Climatic Change. DOI: 10.1007/s10584-017-1905-4
• Ashley, W. S. and S. M. Strader, 2016: Recipe for disaster: How the dynamic ingredients of risk and exposure are changing the tornado disaster landscape. Bulletin of the American Meteorological Society, 97, 767-786.
• Haberlie, A., W. S. Ashley and T. Pingel, 2014: The effect of urbanization on the climatology of thunderstorm initiation. Quarterly Journal of the Royal Meteorological Society. DOI: 10.1002/qj.2499.
• Ashley, W. S., S. Strader, D. Dziubla and A. Haberlie, 2014: Driving blind: Weather-related vision hazards and fatal motor vehicle crashes. Bulletin of the American Meteorological Society. DOI: 10.1002/met.1482.
• Ashley, W. S., S. Strader, T. Rosencrants and A. J. Krmenec, 2014: Spatiotemporal changes in tornado hazard exposure: The case of the expanding bull's eye effect in Chicago, IL. Weather, Climate and Society, 6, 175-193.
• Ashley, W. S., M. L. Bentley and J. A. Stallins, 2012: Urban-induced thunderstorm modification in the Southeast United States. Climatic Change, 113, 481-498.
• Ashley, W. S. and C. W. Gilson, 2009: A reassessment of U.S. lightning mortality. Bulletin of the American Meteorological Society, 90, 1501–1518.
• Ashley, W.S., A.J. Krmenec and R. Schwantes, 2008: Vulnerability due to nocturnal tornadoes. Weather and Forecasting, 23, 795-807.
• Ashley, S.T. and W.S. Ashley, 2008: Flood fatalities in the United States. Journal of Applied Meteorology and Climatology, 47, 805-818.
• Ashley, W.S., 2007: Spatial and temporal analysis of tornado fatalities in the United States: 1880-2005. Weather and Forecasting, 22, 1214-1228.

Grants, Fellowships and Leaves of Absence

• IUCRC Phase I Northern Illinois University: Center for Interdisciplinary Research on Convective Storms (CIRCS). With V. Gensini and A. Haberlie. National Science Foundation, 2025–2030.
• Collaborative Research: Polarimetric Radar and Modeling Perspectives of Updraft, Cold Pool and Mesovortex Evolution in Quasi-Linear Convective Systems. With A. Haberlie. National Science Foundation, 2025–2028.
• In-situ Collaborative Experiment for the Collection of Hail In the Plains (ICECHIP). 2025–2026 field program. With V. Gensini. National Science Foundation, 2024-2028.
• Understanding and Mitigating Future Weather and Climate Risks to Agriculture. With V. Gensini. Community Project Funding, National Oceanic and Atmospheric Administration. 2022-2024.
• Faster, Clearer, Stronger Communication and Action: Building IWT and Vulnerable Resident Connections to Improve Severe Weather Literacy and Outcomes. With S. Strader (Villanova), A. Haberlie (NIU) and J. Henderson (TTU). National Oceanic and Atmospheric Administration, 2021-2024.
• Weather/Climate Modeling, Data Science and Analytics. With V. Gensini, A. Haberlie and A. Michaelis (NIU). Public-private partnership with a mutual company, 2020-2023.
• Collaborative Research: Observed and Future Dynamically Downscaled Estimates of Precipitation Associated with Mesoscale Convective Systems. With V. Gensini (NIU) and R. Schumacher (CSU). National Science Foundation, Climate & Large-scale Dynamics Program and Physical & Dynamic Meteorology Program, 2017-2020.
• Tornadoes and Mobile Homes: An Inter-science Approach to Reducing Vulnerabilities and Improving Capacities for the Southeast's Most Susceptible Population. With S. Strader (Villanova) and K. Klockow (CIMMS). National Oceanic and Atmospheric Administration, 2017-2019.
• Collaborative Research: Climatological and Event-based Radar Delineation of UHI Convection for Urban Corridors within the Southeastern U.S. With M. L. Bentley and J. A. Stallins. National Science Foundation, Geography & Regional Science Program and Physical & Dynamic Meteorology Program, 2007-2012.
• NIU Undergraduate Research and Apprenticeship Program. Spring 2006, fall 2006-spring 2007, fall 2007-spring 2008, fall 2008-spring 2009, fall 2009-spring 2010, fall 2010-spring 2011, fall 2011-spring 2012, fall 2012-spring 2013, fall 2013-spring 2014, fall 2014-spring 2015.
• NIU Research and Artistry Grant. Summer 2006, summer 2008, summer 2014, summer 2017.
• NIU Undergraduate Research Assistantship. Summer 2014, spring 2015.
• NIU Student Engagement Fund. Summer 2015, fall 2015, fall 2016, fall 2017.
• NIU Great Journeys Assistantship. Fall 2014-spring 2015, fall 2015-spring 2016.