K Index

K-Index is a measure of thunderstorm potential based on the vertical temperature lapse rate, and the amount and vertical extent of low-level moisture in the atmosphere.

K= 0 to 18 Stable. No Thunderstorms
K= 19 TO 20 Marginally unstable. Thunderstorms Unlikely.
K= 21 TO 25 Moderately unstable. Isolated Thunderstorms.
K= 26 to 30 Widely Scattered Thunderstorms
K= 31 to 35 Numerous Thunderstorms
K= 36 to 40 Very Unstable. Thunderstorms Very Likely
K=> 40 Extremely Unstable. 100% Chance of Thunderstorms

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

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