| description abstract | AbstractConvective available potential energy (CAPE) is known to lack skill in discussing the environments of tornadic and nontornadic storms, or those of tornado outbreaks and nonoutbreaks. In this paper, a composite analysis of extratropical cyclones that caused 15 or more tornadoes [outbreak cyclones (OCs)] and 5 or fewer tornadoes [nonoutbreak cyclones (NOCs)] in the United States in April and May between 1995 and 2012 shows that entraining-CAPE (E-CAPE), which considers the effects of the entrainment of environmental air, is useful in the analysis of the environments of OCs and NOCs. E-CAPE in the warm sector of OCs is larger than that in the warm sector of NOCs (statistically significant at the 95%?99% level). Moreover, the regions with large E-CAPE for both OCs and NOCs are more closely correlated with the locations of tornadoes than those with large CAPE. The larger E-CAPE near the center in the warm sector of OCs is due to greater moisture at low and midlevels that results from advection by strong southerly winds and synoptic-scale ascent, respectively. The composite analysis also shows that E-EHI, E-SCP, and E-STP, for which traditional CAPE used in the energy helicity index (EHI), supercell composite parameter (SCP), and significant tornado parameter (STP) is substituted by E-CAPE, are more strongly correlated with tornado locations than are the original EHI, SCP, and STP, respectively. | |
