ABSTRACT:

Hydroclimatic extremes such as droughts and floods pose major challenges for water management across Kansas and the broader Great Plains. Climate models have limited ability to predict these extremes, making historical analysis essential for understanding how such events may evolve in the future. Compound extremes — including recurring wet or dry conditions across consecutive years and "weather whiplash" transitions between opposite extremes — add further complexity and uncertainty.
This project aimed to better understand historical patterns and trends in seasonal to annual hydroclimatic extremes in Kansas, organized around three objectives. The first objective focused on quantifying spatiotemporal patterns in compound extremes. Historical precipitation data from meteorological stations and the gridded PRISM dataset were compiled for Kansas and surrounding areas contributing to federal reservoirs. A comparison of these sources confirmed that PRISM accurately reproduces annual and seasonal precipitation totals, with minimal bias in identifying extremes. PRISM was therefore selected for statewide analysis across a 128-year period (1895–2023). A percentile-based classification system was developed to identify six types of extremes: isolated wet and dry events, recurring wet-to-wet and dry-to-dry sequences, and whiplash transitions in both directions, producing a 4 km resolution database of precipitation extremes.
The second objective analyzed changes in compound extremes across water management areas. Annual precipitation is increasing over much of Kansas, with significant long-term wetting trends across 40.3% of the state, driven primarily by increased spring rainfall. Both isolated wet and recurring wet-to-wet extremes have become more widespread since approximately 1980. Results were summarized for 148 management-relevant areas including federal reservoir watersheds, groundwater management districts, and Regional Advisory Committee boundaries. Western reservoirs show persistent drying, while eastern reservoirs exhibit increasingly wet conditions. Whiplash events occur most frequently in summer and are more common in northern and eastern reservoirs. The frequency of wet extremes since reservoir construction is significantly correlated with loss in reservoir storage capacity.
The third objective produced an interactive web-based tool built on ESRI Experience Builder, allowing users to explore visualizations of historical precipitation and extremes for all 148 management boundaries and download the underlying data for further use.

ABSTRACT:

Data associated with the manuscript, "Changing spatiotemporal patterns of seasonal to annual precipitation extremes in the U.S. Great Plains region", by Howlader et al.

Manuscript abstract: Precipitation extremes, such as droughts and floods, stress water management. Compound precipitation extremes include recurring extremes (consecutive wet or dry periods) and ‘weather whiplash’ events (transitions from anomalously wet to anomalously dry periods and vice versa) and are particularly stressful. We developed a percentile-based approach to quantify six typologies of extremes (isolated wet/dry, recurring wet/dry, dry-to-wet and wet-to-dry whiplash) in a consistent manner across time and space and investigated historical spatiotemporal dynamics in seasonal and annual precipitation extremes across the U.S. Great Plains (USGP), which spans 2.1 million km² in parts of 14 states. We identified each extreme type at annual and seasonal timescales and 4 km spatial resolution from 1895 to 2023. Annual and seasonal precipitation is increasing across much of the northern and eastern USGP, particularly during the spring, which is accompanied by significantly more frequent isolated wet and recurring wet extremes. In particular, recurring wet conditions have accelerated dramatically since the 1980s, both annually and in all seasons. In contrast, no annual or seasonal extreme type was decreasing in occurrence at the significance threshold used. Extremes are associated with El Niño–Southern Oscillation (ENSO) dynamics, with extreme wet conditions occurring more frequently during El Niño phases across the central and southern USGP and extreme dry conditions occurring more frequently during La Niña phases. Understanding historical changes offers insight into present and future conditions, and our findings underscore the need for water management strategies resilient to more common wet and recurring wet extremes.