Abstract

Derechos are long-lived, convectively driven windstorms capable of producing widespread and destructive straight-line wind damage. Although their synoptic-scale environments have been broadly documented, localized predictive frameworks remain limited, particularly for smaller geographic regions. This study examines progressive derecho events affecting or occurring within 200 nautical miles of Wayne County, Ohio, with the objective of developing a comprehensive, operationally useful forecasting checklist. Ten well-documented derecho events were analyzed using reanalysis data, archived soundings, radar composites, and storm reports. Environmental parameters were evaluated at 12, 6, and 3 hours prior, and include mid-level flow, low-level thermodynamics, instability indices, shear, and downdraft potential. Results indicate that Wayne County derechos consistently occur within northwest flow regimes on the periphery of a central U.S. ridge; however, the environmental signatures separate into two distinct modes. One mode is thermodynamically dominant, characterized by very high SBCAPE and strong destabilization with comparatively modest deep-layer shear. The other is shear dominant, marked by stronger 0–6 km shear and mid-level flow but comparatively lower instability. Despite differences in magnitude and forcing, these environments can be effectively reduced to the combined parameter space of 0–6 km shear and SBCAPE, which together capture the primary variability and provide the most efficient diagnostic framework for distinguishing derecho-supportive setups. Additionally, 70% of derecho events occurred during La Niña years, suggesting a climatological background pattern favorable for ridge placement and northwest flow, though this signal is more applicable to seasonal outlooks than short-term forecasting. Data on meteorological conditions collected at the time of derecho events were synthesized into a structured, multi-stage derecho confidence index designed to distinguish between instability-dominant and shear-dominant regimes. The resulting checklist provides a practical diagnostic framework for operational forecasters in Wayne County, enhancing preparedness and improving identification of environments capable of supporting progressive, long-track convective wind events.

Advisor

Pollock, Meagen

Department

Environmental Studies; Geology

Keywords

Weather, Derecho, Climate, Storm, Wind

Publication Date

2026

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2026 Neil Edmiston