Application of the GOES-16 Advanced Baseline Imager: Morphology of a Preconvective Environment on 17 April 2019

Abstract

Thunderstorms formed in the afternoon of 17 April 2019 over northern Mexico.  Satellite data are used to highlight several features associated with convective preconditioning over portions of Coahuila, Mexico.  Satellite imagery was used to identify two preconvective features over northern Coahuila:  1) A relatively moist boundary layer inferred from channel differencing of imagery near 10.3 µm and 12.3 µm, and 2) Upward vertical motion inferred from decreasing values of brightness temperatures near 7.34 µm (low-level water vapor).  Due to the approach of a trough at 500 hPa, a larger region of cooling was evident in low-level water vapor imagery.  Evidence of blowing dust in imagery was used to highlight a wind-shift boundary along with a possible region of enhanced horizontal convergence.  A demonstration of a time-of-arrival tracking feature is used to show a benefit to a forecaster in determining the arrival of a region of blowing dust, possible enhanced horizontal convergence and subsequent convective initiation.  Assimilation of satellite data that contains key features and potential benefits to numerical weather prediction is addressed.  Convective preconditioning of an environment outside of the United States, but adjacent to a U.S. county warning area, is an important situation to monitor as subsequent convection may move into a forecaster’s region of responsibility.