The Utility of Sounding and Mesonet Data to Nowcast Thunderstorm Initiation

Abstract

Abstract Previous studies have shown that thunderstorms often form along boundary-layer convergence lines (boundaries) detected by sensitive Doppler radars similar to the WSR-88D. In this paper, high-resolution mesonet observations (10–15-km spacing and 1-min averages) and sounding data (eight stations within 25 000 km2 and 1–6-h frequency) collected in northeast Colorado are examined to determine their utility for forecasting precisely when and where storms initiate along boundaries. Stability indices derived from mesonet and sounding data were useful in identifying stable regions where storm initiation was unlikely. However, in regions where indices indicated a degree of latent instability, storms often did not form and if they did their intensities were not correlated to the magnitude of the instability. Two-dimensional numerical model studies show that in a near-neutral environment (as typical during a Denver, Colorado summer afternoon), surface temperature and/or dewpoint fluctuations of 2–4°C can be...