Diurnal Variations in Severe Weather Forecast Parameters of Rapid Update Cycle-2 Tornado Proximity Environments

Abstract

Abstract Nocturnal tornadoes are disproportionately dangerous compared with their daytime counterparts; thus, it is imperative to improve the forecasting of these tornadoes. This study uses a large (194 cases) and geographically expansive dataset of Rapid Update Cycle tornado proximity (within 80 km of initial tornado touchdown) soundings from 2003 to 2011 to investigate tornado forecast parameter differences between F1–F2 (weak) and F3+ (strong) nocturnal and daytime tornadoes. The findings suggest that, when considered alone, 0–1- and 0–3-km wind shears show the highest skill in distinguishing environments associated with weak and strong tornadoes, with 0–1-km shear being most effective at night and 0–3-km shear showing the most skill during the day. The results also indicate that combining most unstable CAPE with 0–3-km shear and 0–1-km shear with 3–9-km shear resulted in the most skillful daytime and nighttime forecasts, respectively.