Speaker: 
Kerry A. Emanuel, PhD.
Cecil & Ida Green Professor of Atmospheric Science
Lorenz Center
Massachusetts Institute of Technology

Abstract:
Severe thunderstorms, which are often associated with strong winds, hail, and tornadoes, pose substantial threats to people, livestock, and agriculture. While their dynamics are well understood, relatively little is known about how climate change (man‐made or natural) might affect such storms. In this talk, I will focus on one of the main environmental prerequisites for severe storms: Convective Available Potential Energy (CAPE), which is a measure of the potential energy stored in moist atmospheres that can be released explosively when the potential energy barrier that permits its accumulation breaks. I will discuss the work of my former Ph.D. student that shows, rather unexpectedly, that CAPE usually accumulates over only the 6‐8 hours leading up to the storm and that its build‐up is strongly controlled by soil moisture. I will present observational evidence for this as well as a very simple theoretical model and discuss how climate change should affect CAPE and how the new understanding of CAPE may someday allow for seasonal prediction of severe storm activity.