Explicit forecasts of low-level rotation from convection-allowing models for next-day tornado prediction

This motivated the use of RVORT1 as a direct surrogate for tornadoes, without the need to filter forecasts with environmental information. The relationship between UH25 and UH03 was also explored among the simulated storms; UH03 only exceeded UH25 in storms occurring within low-CAPE/high-shear environments, while UH03 rarely exceeded UH25 in traditional supercell environments. Next-day ensemble surrogate severe probability forecasts (E-SSPFs) for tornadoes were generated using these diagnostics for 92 forecasts, with thresholds based on the number of observed tornado reports.

E-SSPFs for tornadoes using RVORT1 and UH03 were more skillful than E-SSPFs using UH25. The UH25 E-SSPFs possessed little skill, regardless of threshold or smoothing length scale. All E-SSPFs suffered from poor sharpness at skillful scales, with few forecast probabilities greater than 40%.