Analysis of distinct thresholds for CAPE and vertical wind shear
covariates to discriminate severe weather environments in the La Plata
Basin using ERA5 reanalysis
Abstract
Severe convective storms are responsible for producing hazardous weather
phenomena, such as tornadoes, damaging winds and large hail, that pose a
threat to life and property in many parts of the world, including the La
Plata Basin in subtropical South America. In this preliminary study,
covariate quantities that describe regimes of severe weather
environments within the CAPE and vertical wind shear parameter space are
computed from atmospheric profiles obtained from the ERA5 gridded data
at 6-hr intervals for a 7-year period (2013-2019) in the La Plata Basin.
These covariates are utilized to assess the magnitude of atmospheric
ingredients known to favor the development of severe convective storms
and to determine days with atmospheric conditions conducive to these
storms. Following similar studies conducted for different regions around
the world (Brooks et al., 2003; Trapp et al., 2009; Allen et al., 2011
and Glazer et al., 2020), distinct threshold values for the covariate
quantity that multiplies mixed-layer CAPE and 0-6km bulk wind difference
are assessed as discriminators for severe weather environments. An
evaluation is conducted on how CAPE and shear covariates computed from
ERA5 represent the seasonal march of severe weather hot spots in the La
Plata Basin as compared to available short-term climatologies based on
actual soundings, ground reports of severe weather, and remote sensing
products.