Weather and climate affect everyone, with some communities particularly vulnerable to severe events such as floods, droughts, heat waves, and tornadoes. Analyses of atmospheric conditions using cutting-edge observational platforms improve model predictions of weather hazards. Research on our climate and its variability, as well as modeling its future changes and impacts on extreme events, is critical for community adaptation and planning to protect lives and property.
ISWS scientists conduct fundamental and translational research, monitoring, services, and outreach to address weather and climate issues significant to Illinois, the Midwest, and the nation. Research examines the physical effects, such as changes in water supply, crop yields, and air quality, and the socioeconomic impacts of weather and climate conditions, including effects on infrastructure and public health vulnerability.
Climate
Weather and climate extremes have motivated extensive research and monitoring efforts to understand the risks faced by Illinois and the world. Climate variability can be thought of as variations in the atmosphere. Typically, climate variability refers to changes that occur over timescales ranging from months to decades. Climate change usually refers to a systematic change in the characteristics of the climate over decades or longer.
Both natural forces, such as sun and ocean conditions, and human activities drive climate change and variability. Human impacts include greenhouse gas emissions and landscape changes, such as the Midwest’s shift from prairie to dense cropland.
Weather
Weather describes the atmospheric conditions we experience daily, measured in minutes to days. One of the most challenging aspects of the atmosphere to predict accurately is the atmospheric boundary layer, where we all live. The boundary layer changes dramatically as the air moves across different surfaces. Observations and numerical modeling simulations have been conducted to predict and understand how this affects weather systems. One challenge is characterizing how the atmosphere responds to surfaces that vary significantly over short distances.
One example is summertime, when cool air from Lake Michigan flows over the warm nearby land areas. Researchers sought to understand how the land heats up and destabilizes the inland-moving air, occasionally resulting in thunderstorms. ISWS partnered with several universities to gather detailed observations of these processes throughout July 2024.
Another example of this is air flowing over a partially frozen lake. Pack ice on lakes can compress together, break apart, and freeze or thaw at different rates across the lake surfaces. ISWS scientists have examined how the atmosphere responds to variable ice cover over Lake Erie using observations from the University of Wyoming King Air aircraft. They found notable differences in air temperature and humidity between regions covered in ice and those with more open water. Surprisingly, the upward sensible heat exchange rate between the lake and the air was significantly influenced by the ice only when it covered over approximately 70% of the lake’s surface.
ISWS scientists use state-of-the-art light detection and ranging systems, also called lidar, to measure highly complex wind systems and the dispersion of atmospheric particles. This technology has enabled unique observations of nighttime drainage flows in the Midwestern U.S., thunderstorm winds, lake and sea breezes, turbulence generated by buildings and wind turbines, and the daytime intensification of vertical air motions that ultimately lead to intense convective storms. The National Science Foundation, the U.S. Department of Energy, Argonne National Laboratory, and others have sponsored recent collaborative projects.
Land-Climate Interactions
Land use and land-use changes can significantly affect local and broader-scale climate and extreme weather events. The impacts of land use can be comparable to increased greenhouse gas emissions.
In recent studies, ISWS scientists have investigated the impact of deforestation on air temperatures, the effects of land use on summer temperature and precipitation, the role of vegetation in the occurrence of flash droughts, and the influence of the Chicago heat island on intense thunderstorm systems and lake-breeze movement through the urban area.
Observations have shown that deforestation, whether due to hardwood harvesting or land clearing for cropland, can significantly affect local high temperature extremes. Simulations from climate models suggest that agricultural expansion across the Great Plains may significantly increase precipitation throughout the crop area. Further, irrigation in summer results in substantial cooling in the irrigated area. Studies have also shown that vegetation greening during spring and summer can significantly increase the occurrence of flash droughts, particularly in the Great Plains and the western U.S. The extent of flash droughts is also affected.
These findings emphasize the importance of land use and management for regional climate and highlight the need to consider land management practices in future assessments of regional climate change and climate mitigation.
Climate Change
Rising temperatures across all seasons are expected to lead to more severe heat waves, heavier rainfall, changes in water supply, air quality issues, and more extreme storms. With historical changes in rainfall intensity and frequency, flooding occurs more often, potentially leading to public health hazards, such as water contamination and exposure to infectious diseases.
ISWS research on climate change and climate variability has focused on drought, damaging spring freezes, extreme heat, changing trends on Lake Michigan, the causes of observed and future trends in rainfall extremes, drought resilience in urban trees and forest ecosystems, and assessing climate impacts on freshwater ecosystems.
A key research goal is to foster better predictions and informed responses to extreme events, both on short- and long-term time scales, where human forces play a significant role.
State Climatologist
The Office of the State Climatologist provides climate information and other services to citizens and organizations in Illinois and surrounding states. The role, belonging to a scientist at ISWS, was created by state statute in the 1950s to serve as the state’s authoritative spokesperson on climate science.
The state climatologist leads climate and drought monitoring, research, and data collection for the state of Illinois. They work with communities, industries, and state agencies on Illinois weather, climate, and climate change issues. They engage the public through online, media, and educational outreach, such as workshops for agriculture and natural resources professionals. The state climatologist also acts as the primary resource for climate science expertise and projections required by state policymakers and agencies, including developing a future climate planning tool for emergency management in Illinois.
Trent Ford has served as the state climatologist since 2019.
Rain & Snowfall
Precipitation, whether excessive or insufficient, can significantly affect communities, the surrounding environment, and our food system. ISWS scientists conduct monitoring and research to improve our understanding of storm impacts and the forces shaping them.
Rainfall & Soil
Long-term monitoring provides the data scientists need to discover emerging trends that take years, decades, or longer. The Illinois Climate Network at ISWS gathers weather, soil, and solar data used by NOAA. The project has 19 stations across the state that monitor weather and soil conditions every five minutes and hourly. Hourly and daily data are available dating back to 1989. The network is part of ISWS’ WARM program, which also monitors water table levels, sediment, and lake levels.
The Illinois Climate Network data is used in current ISWS research to understand rainfall variability and its effects on soil moisture. As trends toward increased precipitation intensity emerge in many U.S. regions, little is known about how these trends will affect drought and soil moisture, and whether drought indices, such as SPI and SPEI, can accurately represent soil moisture under these new patterns. ISWS researchers use hydrologic modeling and observations in watersheds across the Midwest to study how soil responds to precipitation of varying intensity, quantify infiltration and runoff, and assess how these variations affect the efficacy of existing drought indices. Understanding this process extends beyond bridging knowledge gaps about soil moisture; it also shapes our understanding and mitigation strategies for drought and flood events.
Lake-Effect Storms
Lake-effect snowstorms, which develop over the Great Lakes each winter, bring some of the most extreme winter weather to central and eastern North America. Accurate forecasts can help residents and communities prepare for storms by stocking up on food and water, staging snow removal equipment, and arranging for emergency services.
While computational models available to the National Weather Service can predict whether a lake-effect storm will occur, forecasts of which locations will be most affected, how much snow will fall, and the storm’s intensity remain challenging.
ISWS research has focused on understanding the unique characteristics of lake-effect storms and how lake-effect storms have varied over the last century.
ISWS continues to analyze detailed observations collected during the Ontario Winter Lake-effect Systems (OWLeS) field project, a collaboration among nine universities. A special collection of journal articles published by the American Meteorological Society on OWLeS documents unique insights into the evolution of lake-effect convection and precipitation, key transitions in the atmosphere’s response to various surface characteristics, and the lake’s impacts on lake-effect snow and boundary layer depth. Data and observations gathered from the ground and airplanes have improved forecasts for areas affected by lake-effect snowstorms.
This research focuses on accurately describing various types of lake-effect systems based on the turbulent characteristics of the atmosphere within and above the storm. It quantifies the formation of liquid and ice clouds, as well as snow. Additionally, it seeks to understand the entrainment layer, through which most of the growth of the lake-effect storm occurs, and to learn how much snow from nearby cyclones alters and intensifies the snow from lake-effect storms. These studies can enhance model predictions of the weather and provide datasets for analyzing the capability of those models.
Flooding
Flooding is Illinois’ most common natural disaster by a significant margin, causing personal and economic losses to communities across the state. However, the right data, analysis, and modeling can predict flooding in many areas. ISWS scientists collaborate with communities to create the resources they need to safeguard their people and economies and seek federal funding to prevent and recover from disasters. Read more about ISWS flood risk research.
Drought
Drought profoundly impacts communities and food production, and is common in Illinois. ISWS scientists study drought to improve our understanding of this phenomenon as we assess how a changing climate will affect what to expect from droughts in the future. Read more about ISWS drought research.
Heat Waves
Due to climate change, heat waves are becoming increasingly frequent and intense in Illinois. The risks posed by heat waves and storms in urban and rural parts of Illinois can significantly affect vulnerable communities. In metropolitan regions of the state, the heat island effect often intensifies heat, as limited green space influences the temperatures city residents feel. In rural areas of Illinois, limited access to healthcare services, heat mitigation services like cooling centers, and a prevalence of outdoor work heighten vulnerability to extreme heat.
ISWS scientists study the land processes that affect heat waves to better understand them and improve forecasts for these communities. The research uses satellite datasets to examine three major U.S. cities with unique geography, climate, and urban characteristics. It aims to develop methods that other cities could use to assess their urban environment and risks. The work also evaluates green infrastructure, identifies mitigation strategies, and highlights vulnerable communities that could benefit from them.