Convective Available Potential Energy (CAPE) is a measure of the instability of the atmosphere and defines the vertically integrated positive buoyancy of a rising parcel. It is a good indicator of general instability, and convection tends to be more vigorous with higher values.

 CAPE < 300: Stable.
 CAPE 300 to 1000: Marginally unstable.
 CAPE 1000 to 2500: Moderately unstable.
 CAPE 2500 to 3000: Very unstable.
 CAPE 3000 to 5000: Extremely unstable.
 CAPE > 5000: Whoa Nelly!

Other UKAWC Stability Indices:
Lifted Index (LI) K-Index CIN Showalter Index SWEAT Total Totals

Ag Weather Center, Department of Biosystems & Agricultural Engineering, University of Kentucky